08.05.2014 Views

Download the PDF - Optometry Today

Download the PDF - Optometry Today

Download the PDF - Optometry Today

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Continuing Education<br />

Adrian Parnaby-Price, MA, MB, BChir, (Cantab), FRCSEd<br />

The College of<br />

Optometrists<br />

sponsored by<br />

Clinical decision making<br />

in ocular emergencies<br />

The optometrist is <strong>the</strong> first professional contacted by many people<br />

suffering acute ophthalmological conditions. It is, <strong>the</strong>refore,<br />

important that <strong>the</strong>se are recognised and managed effectively,<br />

especially those conditions in which prompt treatment has <strong>the</strong><br />

potential to significantly improve <strong>the</strong> outcome.<br />

The key to management of ocular<br />

problems, and especially in emergencies,<br />

lies in <strong>the</strong> successful diagnosis of <strong>the</strong><br />

condition. Unfortunately, even in<br />

specialist ophthalmic centres, <strong>the</strong><br />

precise diagnosis is not always possible<br />

but recognition of features and patterns<br />

often suggest <strong>the</strong> nature of <strong>the</strong> problem<br />

and are usually enough to guide <strong>the</strong><br />

basic management. Whilst specific areas<br />

are covered in o<strong>the</strong>r parts of this series<br />

(e.g. <strong>the</strong> red eye), <strong>the</strong> aim of this article<br />

is to suggest features of <strong>the</strong> presentation<br />

which will be of help in reaching a<br />

diagnosis upon which management of<br />

specific emergencies can be undertaken.<br />

HISTORY<br />

The limited range of symptoms<br />

pertaining to <strong>the</strong> eye means that most<br />

ophthalmic histories are fairly brief.<br />

Despite this, <strong>the</strong>re is often enough<br />

information to provide clues to <strong>the</strong><br />

underlying pathology or to exclude<br />

o<strong>the</strong>rs. Hence, <strong>the</strong> history of a sudden,<br />

painless loss of vision in an older patient<br />

known to be on medication for high<br />

blood pressure tends to imply a vascular<br />

cause ra<strong>the</strong>r than an inflammatory one.<br />

Pre-existing disease<br />

It is always useful to start <strong>the</strong> history<br />

with a brief question about <strong>the</strong> eyes<br />

before <strong>the</strong> onset of <strong>the</strong> presenting<br />

problem. Previous amblyopia, uveitis or<br />

ocular surgery might influence<br />

subsequent management.<br />

General health<br />

Of particular relevance to ophthalmic<br />

problems are systemic conditions which<br />

are associated with ocular disease,<br />

particularly cardiovascular conditions<br />

(associated with cerebrovascular<br />

accidents and retinal vascular occlusion)<br />

and generalised inflammatory conditions<br />

(associated with uveitis and scleritis).<br />

Many patients are surprisingly reticent<br />

about previous illness which <strong>the</strong>y do not<br />

consider might be related to a problem<br />

with <strong>the</strong> eye and few volunteer a<br />

comprehensive list. It is wise to<br />

formulate a rapid system to work through<br />

this area. A general question to begin<br />

might be - “Apart from your eyes are you<br />

well?” followed by a specific series of<br />

questions to run through disease<br />

associations, for example, “Do you have<br />

high blood pressure or diabetes; have you<br />

had any heart attacks or strokes; have<br />

anything wrong with your joints, bowels,<br />

heart or lungs?”. In cases where <strong>the</strong>re is<br />

little history forthcoming or <strong>the</strong><br />

converse, where a potentially complex<br />

history begins to emerge, it is also wise to<br />

ask for details of any medication. “Do<br />

you take any tablets, pills, puffers,<br />

patches or injections for anything?” -<br />

may rapidly summarise <strong>the</strong> kind of<br />

medical problems which are currently<br />

active and serious enough to require<br />

regular treatment.<br />

PRESENTING COMPLAINT<br />

This can often be summarised concisely<br />

into: 1) whe<strong>the</strong>r <strong>the</strong> vision is affected or<br />

not, what is <strong>the</strong> nature of any visual<br />

problems and what degree of visual<br />

impairment exists; 2) whe<strong>the</strong>r <strong>the</strong> eye is<br />

painful; 3) whe<strong>the</strong>r <strong>the</strong> eye is red; and 4)<br />

<strong>the</strong> speed of onset and duration of any<br />

symptoms (sudden, rapid, slow). This is<br />

actually entirely adequate for <strong>the</strong><br />

assessment of <strong>the</strong> majority of cases and it<br />

is unusual to find ocular problems which<br />

require more detailed questioning or<br />

which, once a painstaking history has<br />

The College of Optometrists has awarded<br />

this article 2 CET credits. There are 12<br />

MCQs with a pass mark of 66%.<br />

been taken, cannot be summarised in<br />

this form. Remember that <strong>the</strong> physical<br />

findings are often more important in<br />

determining <strong>the</strong> management which is<br />

<strong>the</strong> end-point of a consultation, and that<br />

certain points can be reviewed after <strong>the</strong><br />

examination.<br />

Particular features of a history which<br />

might be important in diagnosis and<br />

management are:<br />

Visual acuity<br />

This is often <strong>the</strong> reason for seeking a<br />

consultation and may be described in a<br />

variety of ways by <strong>the</strong> patient. ‘Blurring’<br />

of vision has been use to describe almost<br />

any degree of visual impairment from<br />

distortion with no loss of Snellen acuity<br />

to perception of light. Always try to get<br />

an accurate description of <strong>the</strong><br />

impairment: can <strong>the</strong> patient still read,<br />

watch television, drive a car safely? Is <strong>the</strong><br />

description simply a reduction in acuity<br />

or is <strong>the</strong> patient describing loss of a part<br />

of <strong>the</strong> visual field? The degree of loss may<br />

in itself aid differentiation but large<br />

visual field defects may cause serious<br />

disability and yet still allow a good<br />

Snellen acuity. Occasionally, visual loss is<br />

transient, in which case it is important to<br />

get a detailed description about each<br />

occasion when vision has been lost.<br />

What exactly was <strong>the</strong> patient doing<br />

when <strong>the</strong> vision went and how quickly<br />

did it go; how long was it gone for and<br />

how bad was vision at its worst; how<br />

quickly did it return? For example,<br />

transient occlusion of <strong>the</strong> vertebrobasilar<br />

artery during extreme neck<br />

movements might affect vision only<br />

when driving.<br />

Distortion of vision<br />

Conditions altering <strong>the</strong> anatomy of <strong>the</strong><br />

fovea, such as oedema or sub-retinal<br />

neovascularisation, cause distortion of<br />

<strong>the</strong> retinal photoreceptor position and<br />

this has secondary effects on vision. In<br />

2<br />

APRIL 9 • 1999 OPTOMETRY TODAY


Clinical decision making in ophthalmic emergencies<br />

sponsored by<br />

DISTANCE LEARNING MODULE 1 PART 4<br />

more severe distortions, straight lines<br />

become bent or kinked (door frames are<br />

often among <strong>the</strong> first objects to be noted<br />

as affected). Retinal oedema causes <strong>the</strong><br />

photoreceptors to be displaced apart<br />

from each o<strong>the</strong>r and <strong>the</strong> patient<br />

experiences micropsia where <strong>the</strong> same<br />

size retinal image falls upon fewer<br />

photoreceptors and is, <strong>the</strong>refore,<br />

interpreted as being smaller than in <strong>the</strong><br />

fellow eye. This symptom is, <strong>the</strong>refore,<br />

highly suggestive of foveal pathology and<br />

may be reliably documented with an<br />

Amsler chart.<br />

Pain<br />

This is a feature of a variety of conditions<br />

but, when linked to o<strong>the</strong>r parts of <strong>the</strong><br />

presenting problem, can be important in<br />

establishing a diagnosis. A foreign body<br />

most commonly gives rise to a pricking<br />

sensation and uveitis is more commonly<br />

described as an achy pain with specific<br />

exacerbation in light (photophobia). The<br />

lack of pain might be important as<br />

retinal detachment and vascular events<br />

are painless despite profound visual<br />

disturbance.<br />

Discharge and tearing<br />

Surface problems, such as conjunctivitis<br />

and foreign bodies, cause irritation and<br />

activate defence mechanisms to give rise<br />

to increased secretions. Whilst a watery<br />

discharge in a case of conjunctivitis<br />

might suggest a diagnosis of viral, as<br />

opposed to bacterial, conjunctivitis in<br />

which <strong>the</strong> discharge is more purulent, it<br />

is important to put this feature into its<br />

full clinical context. A watery,<br />

discharging eye is a feature of many more<br />

conditions including severe immune<br />

conditions of <strong>the</strong> sclera in which<br />

perforation of <strong>the</strong> globe is a possibility<br />

and a full history and examination is<br />

imperative.<br />

Flashing lights and floaters<br />

Toge<strong>the</strong>r, <strong>the</strong>se are symptoms of a<br />

posterior vitreous detachment which is<br />

<strong>the</strong> mechanism by which holes are<br />

formed in <strong>the</strong> retina leading to a retinal<br />

detachment. Floaters alone might<br />

indicate inflammation in <strong>the</strong> vitreous<br />

and may be symptomatic only during<br />

reading. Because of <strong>the</strong> paucity of<br />

symptoms from even a large retinal<br />

detachment, <strong>the</strong>se apparently trivial<br />

symptoms should always be treated<br />

seriously as a potential emergency and<br />

mean that a peripheral hole must<br />

specifically be excluded at examination<br />

which cannot be done without pupil<br />

dilation and indirect ophthalmoscopy.<br />

Specific history<br />

Always consider <strong>the</strong> possibility of<br />

trauma, although this is not always<br />

straightforward. Several days can elapse<br />

between metallic foreign bodies entering<br />

<strong>the</strong> eye and <strong>the</strong> onset of symptoms and<br />

some patients (especially children) may<br />

be unwilling or unable to admit to<br />

accident or assault. Chemical injury to<br />

<strong>the</strong> eye must be specifically considered<br />

and excluded. Contact lens use<br />

represents a particular risk for keratitis<br />

and, if lenses are implicated in <strong>the</strong><br />

complaint, it is important to ensure that<br />

<strong>the</strong> daily routine is established,<br />

particularly patterns of wear and<br />

sterilisation methods. All lenses, cases<br />

and solutions should be available for<br />

microbiological examination if possible.<br />

EXAMINATION<br />

Whilst <strong>the</strong> history of <strong>the</strong> problem may<br />

be sketchy or brief, <strong>the</strong> key to diagnosis<br />

is often <strong>the</strong> pattern of pathology based<br />

on <strong>the</strong> findings of <strong>the</strong> clinical<br />

examination and <strong>the</strong> diagnosis may<br />

become clear within moments. Even<br />

quite complex neuro-ophthalmological<br />

conditions may be successfully<br />

diagnosed despite <strong>the</strong> absence of<br />

findings in <strong>the</strong> eye. This part of <strong>the</strong><br />

consultation is, <strong>the</strong>refore, very<br />

important and needs to be undertaken<br />

systematically. Attempts to skip a<br />

complete assessment from <strong>the</strong> outer<br />

eyelids and lashes to <strong>the</strong> retina and discs<br />

will mean that clues may be missed.<br />

Visual acuity<br />

The first part of <strong>the</strong> examination must<br />

be <strong>the</strong> visual acuity in each eye both<br />

unaided and best corrected or using a<br />

pin-hole. Whilst it is occasionally<br />

overlooked in a busy practice, especially<br />

if pathology is clearly identified from <strong>the</strong><br />

outset, it is important to ensure that on<br />

every occasion it is recorded clearly in<br />

any notes. Acuity is sometimes <strong>the</strong> most<br />

useful guide to <strong>the</strong> differentiation<br />

between minor problems and more<br />

serious pathology and is considered a<br />

critical part of any legal analysis of<br />

medical notes.<br />

Colour vision<br />

This is a measure of higher processing<br />

functions but, in severe problems, <strong>the</strong><br />

more useful guide is subjective<br />

sensitivity to red targets. In <strong>the</strong> early<br />

stages of optic nerve disease, <strong>the</strong>re is a<br />

perceived reduction in <strong>the</strong> brightness of<br />

a red target such as a pen top. In<br />

conditions such as acute thyroid eye<br />

disease or orbital cellulitis, in which<br />

<strong>the</strong>re is rapidly increasing orbital<br />

pressures and optic nerve compression,<br />

loss of acuity is a late sign and nerve<br />

swelling occurs even later (by at least 24<br />

hours).<br />

Visual fields<br />

A fur<strong>the</strong>r aid to <strong>the</strong> diagnosis is <strong>the</strong><br />

visual fields. In an emergency setting,<br />

simple patterns are often all that is<br />

required which may be performed with a<br />

red target such as a hat-pin without<br />

complex automated perimetry. The aim<br />

is to identify which part or parts of <strong>the</strong><br />

visual field are affected and it is vital to<br />

ensure that <strong>the</strong> fellow eye is examined as<br />

well. There are a number of classical<br />

patterns of visual field loss but <strong>the</strong><br />

overwhelming majority of patients fit<br />

into one of only a half-dozen or so.<br />

It is simple to consider each field as<br />

consisting of only eight areas (Figure 1).<br />

Each is ‘normal’, ‘impaired’or ‘lost’. Any<br />

findings are, <strong>the</strong>refore, clearer and can<br />

more easily fit a pattern such as<br />

hemianopia, unilateral loss, etc.<br />

The next important features of <strong>the</strong><br />

defect are whe<strong>the</strong>r it extends to central<br />

fixation or not and whe<strong>the</strong>r <strong>the</strong> defects<br />

are centred on <strong>the</strong> blind spot (suggesting<br />

optic nerve disease or larger retinal<br />

vascular problems) or horizontal and<br />

vertical meridia (bilateral mid-line<br />

patterns are generally post-chiasmal and<br />

in <strong>the</strong> brain).<br />

Common patterns and potential<br />

diagnoses include: 1) Hemianopia;<br />

usually homonymous (Figure 2),<br />

suggesting cerebrovascular accident<br />

(CVA, stroke) involving <strong>the</strong> optic<br />

radiations or occipital cortex; may be<br />

bitemporal (Figure 3) suggesting a<br />

lesion at <strong>the</strong> optic chiasm; 2) gross loss<br />

of one field centred on blind spot<br />

(optic nerve involvement such as optic<br />

neuritis or optic nerve tumour) (Figure<br />

4); 3) quadrantanopia (Figure 5) (CVA<br />

in ei<strong>the</strong>r temporal or parietal lobe where<br />

superior and inferior fields have different<br />

pathways); 4) central hemianopia<br />

(Figure 6) (occipital cortex tip lesion);<br />

5) hemianopia sparing central vision<br />

(Figure 7) (occipital cortex lesion with<br />

sparing of occipital tip); and 6)<br />

altitudinal defect (Figure 8) (branch<br />

retinal artery or vein occlusion).<br />

In cases of CVA or tumour-related<br />

disease, <strong>the</strong>re may be o<strong>the</strong>r signs to aid<br />

diagnosis, such as cranial nerve lesions,<br />

which should be considered.<br />

Ocular examination<br />

In an attempt to reach a rapid diagnosis,<br />

it is important not to miss any ocular<br />

APRIL 9 • 1999 OPTOMETRY TODAY 3


sponsored by<br />

Clinical decision making in ophthalmic emergencies<br />

Figure 1<br />

Basic visual fields showing 8<br />

areas and blind spot<br />

Figure 2<br />

Homonymous hemianopia<br />

respecting fixation - CVA<br />

affecting optic radiations<br />

Figure 3<br />

Bitemporal hemianopia<br />

- chiasmal lesion<br />

Figure 4<br />

Loss of one complete visual<br />

field - optic nerve disease<br />

Figure 5<br />

Quadrantanopia<br />

- temporal lobe CVA<br />

Figure 6<br />

Central hemianopia<br />

- occipital cortex tip lesion<br />

Figure 7<br />

Hemianopia sparing central<br />

vision - occipital cortex<br />

sparing tip<br />

Figure 8<br />

Altitudinal defect - inferior<br />

branch vascular occlusion<br />

DISTANCE LEARNING MODULE 1 PART 4<br />

features which may assist diagnosis or<br />

management. It is wise to consider <strong>the</strong><br />

history and symptoms when trying to<br />

identify pathology but, at <strong>the</strong> same time,<br />

each part of <strong>the</strong> eye should be<br />

systematically considered. Even in <strong>the</strong><br />

most dramatic cases, consider first <strong>the</strong><br />

eyelids, <strong>the</strong>n <strong>the</strong> conjunctiva, cornea,<br />

anterior chamber, iris and pupil, vitreous,<br />

retina and disc individually. Always<br />

perform a careful assessment of <strong>the</strong> pupils<br />

for an afferent defect which will indicate<br />

optic nerve disease. A relative afferent<br />

pupillary defect may be present in eyes<br />

with normal vision, although <strong>the</strong> reaction<br />

will not be present when both optic nerves<br />

are equally damaged. The intraocular<br />

pressure (IOP) must be measured before<br />

dilation, even in apparently<br />

straightforward cases. Testing <strong>the</strong> IOP and<br />

<strong>the</strong> pupil are vital in <strong>the</strong> assessment of<br />

patients. For example, in a case of retinal<br />

vascular occlusion, <strong>the</strong> IOP and <strong>the</strong><br />

presence or absence of an afferent<br />

pupillary defect at presentation are key<br />

points in <strong>the</strong> subsequent management. If<br />

<strong>the</strong> patient is already dilated, <strong>the</strong>se cannot<br />

be reliably re-assessed.<br />

In assessing a red eye, <strong>the</strong> green light<br />

filter on <strong>the</strong> slit lamp should be used. This<br />

has <strong>the</strong> effect of bringing <strong>the</strong> red vessels<br />

into much sharper relief by removing<br />

discoloration and allows a much clearer<br />

identification of which layer is injected<br />

(i.e. conjunctiva, episclera or sclera).<br />

Non-ocular signs may exist such as<br />

swollen pre-auricular lymph nodes in viral<br />

conjunctivitis and cranial nerve lesions.<br />

INVESTIGATIONS<br />

These are based on <strong>the</strong> clinical findings<br />

and are often aimed at non-ocular<br />

associations.<br />

Imaging ultrasound, X-rays, MRI<br />

(magnetic resonance imaging) and CT<br />

(computerised tomography) scans are<br />

useful and widely available techniques to<br />

allow detailed examination of non-visible<br />

tissues. B-scan ultrasound is safe and<br />

widely used in ophthalmic departments. It<br />

is most useful in imaging eyes in real-time<br />

for vitreous haemorrhage and scleritis of<br />

<strong>the</strong> posterior globe (which is seen as<br />

thickening and increased signal return).<br />

X-rays are still widely used to identify<br />

sinusitis and breaks in <strong>the</strong> zygoma and<br />

orbital floor following trauma, although<br />

MRI and CT scans are often preferred. CT<br />

scans are currently fairly cheap and widely<br />

available and allow identification of bony<br />

and soft tissue lesions in <strong>the</strong> orbits and<br />

skull. MRI scans tend to be better for<br />

imaging some lesions, particularly<br />

demyelinating lesions (multiple sclerosis<br />

4<br />

APRIL 9 • 1999 OPTOMETRY TODAY


sponsored by<br />

Clinical decision making in ophthalmic emergencies<br />

DISTANCE LEARNING MODULE 1 PART 4<br />

lesions). MRI cannot, however, be used<br />

in those patients with magnetic metals<br />

such as steel in <strong>the</strong> field being examined<br />

as it causes movement and heating of <strong>the</strong><br />

metal. Any suspected foreign body<br />

should be considered when selecting <strong>the</strong><br />

method of imaging.<br />

Microbiology<br />

The isolation of an organism as part of<br />

<strong>the</strong> management of ocular infection is<br />

not always critical if it is mild and<br />

responds to conventional treatment. In<br />

conjunctivitis, most cases are likely to be<br />

self-limiting and conjunctival swabs are<br />

rarely sent. Bacteria can be seen in small<br />

numbers on swabs after brief processing<br />

has been performed to allow a rough<br />

guide as to <strong>the</strong> kind of organisms<br />

involved and, if requested,<br />

microbiological departments can<br />

comment on swabs within hours. Specific<br />

antibiotic sensitivity will not be available<br />

for several days after samples are taken<br />

which is usually too late to influence<br />

initial management.<br />

Wherever possible, samples should be<br />

taken before any antibiotic treatment is<br />

instigated and unpreserved analgesic<br />

drops used as required to allow corneal<br />

scrapes. If treatment is already in<br />

use (including over-<strong>the</strong>-counter<br />

preparations), details should be<br />

forwarded to <strong>the</strong> microbiologist with <strong>the</strong><br />

sample.<br />

Viral swabs have to be transferred<br />

into cultured cells to allow replication<br />

and subsequent identification which<br />

takes several days and prevents rapid<br />

identification. In suspected viral<br />

infections, serology of <strong>the</strong> patient’s<br />

changing antibody levels in response to<br />

<strong>the</strong> infection may be <strong>the</strong> only way to<br />

identify <strong>the</strong> virus.<br />

Particular cases, where identification<br />

of <strong>the</strong> organism is crucial, include<br />

endophthalmitis and acanthamoeba<br />

keratitis where prolonged and intensive<br />

treatment will be required with<br />

implications for <strong>the</strong> prognosis. In<br />

contact-lens related infection, <strong>the</strong> lenses,<br />

case and cleaning solutions should be<br />

sent for analysis.<br />

Blood tests<br />

Many of <strong>the</strong>se are for systemic<br />

associations of ocular pathology and are<br />

focused about specific diagnoses. In<br />

arterial occlusion, <strong>the</strong> most important<br />

differential diagnosis is between<br />

inflammatory and non-inflammatory<br />

causes and an ESR (erythrocyte<br />

sedimentation rate) and CRP<br />

(C-reactive protein) level is mandatory<br />

(both are non-specific measures of<br />

generalised inflammatory activity but<br />

not diagnostic of specific conditions in<br />

<strong>the</strong>mselves). Vascular occlusions<br />

generally require blood counts for<br />

clotting predispositions such as excess<br />

haemoglobin and platelet levels,<br />

inflammatory and clotting diseases and<br />

serum markers for a<strong>the</strong>rosclerosis<br />

(cholesterol and fat levels). Acute<br />

proptosis requires investigations centred<br />

on inflammatory conditions but<br />

especially for antibodies implicated in<br />

thyroid disease (<strong>the</strong> most common cause<br />

of both unilateral and bilateral<br />

proptosis).<br />

TREATMENT<br />

Comprehensive and detailed<br />

management of individual conditions is<br />

beyond <strong>the</strong> scope of this article but many<br />

are covered in o<strong>the</strong>r articles in <strong>the</strong> CPD<br />

series. The following are some of <strong>the</strong><br />

more common conditions, particularly<br />

those that are potentially serious or in<br />

which effective management may<br />

improve <strong>the</strong> outcome.<br />

VASCULAR EMERGENCIES<br />

Central and branch<br />

retinal artery occlusion<br />

The most important investigations once<br />

diagnosis has been made are <strong>the</strong> ESR<br />

and CRP (see above). On this basis,<br />

arterial occlusion is presumed to be<br />

ei<strong>the</strong>r non-arteritic (thrombo-embolic in<br />

origin) or arteritic (inflammatory in<br />

origin).<br />

Non-arteritic CRAO (Figure 9)<br />

Treatment can be very effective if<br />

administered within 24 hours of onset<br />

and hinges around attempts to dislodge<br />

<strong>the</strong> embolus to <strong>the</strong> retinal periphery<br />

where loss of blood supply will cause<br />

limited damage to <strong>the</strong> vision. This is<br />

achieved in <strong>the</strong> first instance by globe<br />

massage in much <strong>the</strong> same way as a<br />

plunger is used on a blocked domestic<br />

pipe. The patient closes <strong>the</strong> eye and two<br />

fingers are used to press on <strong>the</strong> closed<br />

lids firmly and continuously for around a<br />

minute to build up <strong>the</strong> intraocular<br />

pressure. The fingers are <strong>the</strong>n suddenly<br />

removed to drop <strong>the</strong> IOP rapidly and<br />

dislodge <strong>the</strong> embolus. The process is<br />

repeated at one-minute intervals and<br />

can be continued en-route to <strong>the</strong> nearest<br />

ophthalmic unit. Some authorities<br />

advocate a firm rubbing of <strong>the</strong> closed eye<br />

to achieve a similar fluctuation in IOP.<br />

Steps are subsequently taken to reduce<br />

<strong>the</strong> pressure opposing arterial blood flow<br />

Figure 9<br />

Central retinal artery occlusion with cherry red<br />

spot. Note a cilioretinal artery preserving a<br />

small area of normal retina adjacent to <strong>the</strong><br />

disc for comparison<br />

(<strong>the</strong> greatest and most flexible<br />

component of which is, again, <strong>the</strong> IOP)<br />

and help to push <strong>the</strong> embolus fur<strong>the</strong>r<br />

along <strong>the</strong> vessel. IOP may be reduced by<br />

pharmacological means including<br />

conventional glaucoma medication and<br />

acetazolamide and can be reduced by<br />

breathing higher levels of carbon<br />

dioxide. This causes venous dilatation<br />

with a fall in back-pressure and this is<br />

most easily achieved by asking <strong>the</strong><br />

patient to brea<strong>the</strong> in and out of a paper<br />

bag. IOP may be most rapidly and<br />

efficiently dropped by anterior chamber<br />

paracentesis. This entails sitting <strong>the</strong><br />

patient on a slit lamp and anaes<strong>the</strong>tising<br />

<strong>the</strong> eye with topical drops before a fine<br />

needle mounted on a syringe without a<br />

plunger is inserted into <strong>the</strong> anterior<br />

chamber through <strong>the</strong> limbus. 0.1-0.3ml<br />

of aqueous is removed before <strong>the</strong> needle<br />

is withdrawn and, because fluid is not<br />

compressible, IOP falls profoundly.<br />

Management in <strong>the</strong> longer term is to<br />

maintain a low IOP and to treat<br />

underlying risk factors such as<br />

a<strong>the</strong>rosclerosis, hypertension and, in<br />

some cases, oral anti-coagulation with<br />

aspirin or warfarin.<br />

Arteritic (inflammatory) CRAO<br />

Whilst producing a similar ocular picture<br />

to embolic disease, inflammation of <strong>the</strong><br />

arterial walls also produces retinal artery<br />

occlusion. This is a process similar to<br />

arteritic anterior ischaemic optic<br />

neuropathy (see over).<br />

Anterior ischaemic optic neuropathy<br />

This is <strong>the</strong> occlusion of <strong>the</strong> posterior<br />

ciliary arteries causing infarction of <strong>the</strong><br />

optic nerve head. Visual loss is rapid and<br />

APRIL 9 • 1999 OPTOMETRY TODAY 5


sponsored by<br />

Clinical decision making in ophthalmic emergencies<br />

DISTANCE LEARNING MODULE 1 PART 4<br />

Figure 10<br />

New vessels at <strong>the</strong> optic disc in severe<br />

diabetic retinopathy<br />

Figure 11<br />

Vitreous haemorrhage from disc new vessels<br />

profound and irreversible with an early<br />

relative afferent pupil defect. Although<br />

anecdotal reports exist of partial visual<br />

loss and of some recovery of vision, this<br />

is unusual and a history of intermittent<br />

loss of vision should suggest a different<br />

diagnosis. As in CRAO, two variants are<br />

recognised, non-arteritic and arteritic.<br />

Non-arteritic AION<br />

This is probably a variant of CRAO with<br />

a<strong>the</strong>rosclerosis as <strong>the</strong> underlying<br />

associated or causative pathology.<br />

Management is similar to CRAO with<br />

reduction in IOP, aspirin and anticoagulation<br />

as <strong>the</strong>rapeutic options in <strong>the</strong><br />

acute phase and management of<br />

a<strong>the</strong>rosclerotic associations in <strong>the</strong><br />

follow-up period.<br />

Arteritic AION<br />

(and arteritic CRAO - see above)<br />

This is most commonly associated with<br />

temporal arteritis. This condition almost<br />

exclusively affects <strong>the</strong> over-70s and cases<br />

under <strong>the</strong> age of 55 are rare. Temporal<br />

arteritis is associated with polymyalgia<br />

rheumatica in which <strong>the</strong>re is usually a<br />

long history of non-specific illness,<br />

weight loss, pain, wasting and weakness<br />

of muscles of <strong>the</strong> upper legs, upper arms<br />

and shoulders with difficulty in raising<br />

<strong>the</strong> arms above <strong>the</strong> shoulders to brush<br />

<strong>the</strong> hair. Temporal arteritis also causes a<br />

tender scalp and jaw claudication<br />

(progressive weakness and pain on<br />

chewing). Blood tests characteristically<br />

reveal a very high ESR and CRP and<br />

biopsy of <strong>the</strong> temporal artery provides<br />

typical changes of inflammation in <strong>the</strong><br />

walls of <strong>the</strong> vessel. Surgical biopsy of a<br />

section of <strong>the</strong> temporal artery is <strong>the</strong> most<br />

accurate diagnostic test of temporal<br />

arteritis. Initial management is with very<br />

high doses of intravenous steroids and<br />

maintenance on oral steroids at a high<br />

dose for several weeks with a gradual<br />

reduction over not less than 1-2 years.<br />

Few reports exist of any recovery of vision<br />

in <strong>the</strong> affected eye despite rapid<br />

treatment, but <strong>the</strong> aim is to preserve <strong>the</strong><br />

second eye and prevent spread to o<strong>the</strong>r<br />

arteries such as <strong>the</strong> basilar artery in <strong>the</strong><br />

brain with secondary, usually fatal<br />

cerebrovascular accident. Generalised<br />

symptoms of polymyalgia rheumatica and<br />

temporal arteritis rapidly improve on<br />

treatment.<br />

Central and branch<br />

retinal vein occlusion<br />

The acute management of vein<br />

occlusions is aimed at reducing <strong>the</strong><br />

tendency to form thrombus and to<br />

increase venous drainage from <strong>the</strong> retina.<br />

Acutely investigations need to exclude or<br />

correct high levels of haemoglobin or<br />

platelets and any fluid deficit. O<strong>the</strong>r<br />

factors which need to be specifically<br />

addressed are those tending to thrombus<br />

including oral contraceptive use in<br />

women and o<strong>the</strong>r conditions affecting<br />

clotting. Current opinion is divided as to<br />

whe<strong>the</strong>r anti-coagulation is of benefit in<br />

<strong>the</strong> acute phase as <strong>the</strong> retinal picture is<br />

haemorrhagic and could potentially be<br />

worsened. After three months oral<br />

aspirin, which selectively reduces platelet<br />

activity, is widely used although <strong>the</strong> dose<br />

at which benefit may occur is uncertain.<br />

In <strong>the</strong> longer term, trials to reduce<br />

haemoglobin levels by isovolaemic<br />

haemodilution in patients fulfilling<br />

certain criteria have produced scant<br />

evidence that this may help but this<br />

technique is not widely used.<br />

Vitreous haemorrhage<br />

This usually presents with a painless loss<br />

of vision although it may be associated<br />

with ocular trauma. There is usually a<br />

specific cause for <strong>the</strong> haemorrhage which<br />

include new vessels from diabetes<br />

(Figure 10 and 11), an old retinal<br />

vascular occlusion and from posterior<br />

vitreous detachment with avulsion of a<br />

retinal vessel. Whilst <strong>the</strong> haemorrhage<br />

will clear spontaneously with time, <strong>the</strong><br />

biggest problem arises from <strong>the</strong> potential<br />

for progression of o<strong>the</strong>r pathology. All<br />

cases should be managed as a potential<br />

retinal detachment identified by<br />

ultrasound of <strong>the</strong> eye or by indirect<br />

ophthalmoscopy. Such cases may need<br />

vitrectomy to clear <strong>the</strong> haemorrhage<br />

before proceeding to management of<br />

associated problems.<br />

Cerebrovascular accident<br />

(CVA, stroke)<br />

This is <strong>the</strong> result of problems with <strong>the</strong><br />

blood supply to <strong>the</strong> brain and is usually<br />

<strong>the</strong> result of a<strong>the</strong>rosclerosis. There are<br />

two main types: ischaemic, in which<br />

vessels ei<strong>the</strong>r tend to occlude (with loss<br />

of <strong>the</strong> blood supply to <strong>the</strong> brain); and<br />

haemorrhagic when vessels bleed into<br />

<strong>the</strong> tissue of <strong>the</strong> brain. A third type is <strong>the</strong><br />

transient form in which symptoms<br />

resolve within 24 hours and which are<br />

considered to be due to small emboli<br />

(transient ischaemic attacks - TIAs).<br />

The exact clinical picture depends upon<br />

<strong>the</strong> site of <strong>the</strong> problem but can produce a<br />

bewildering variety of symptoms and<br />

signs. Presentations include single or<br />

multiple nerve palsies of any of <strong>the</strong><br />

ocular and associated nerves and<br />

particular patterns of visual field loss<br />

including hemianopias, quadrantanopias<br />

and, occasionally, loss of only small parts<br />

of field around fixation or central vision<br />

(due to lesions at <strong>the</strong> tip of <strong>the</strong> occipital<br />

lobe). Many neurological problems may<br />

be apparent from a good history and<br />

clinical examination (especially of visual<br />

fields) and require urgent investigation<br />

and management firstly to reduce risk<br />

factors for CVA and also to exclude<br />

o<strong>the</strong>r causes of neurological damage such<br />

as intracranial tumours, abscesses and<br />

inflammatory conditions involving <strong>the</strong><br />

brain.<br />

TRAUMA<br />

Most traumatic conditions will require<br />

specific surgery to correct <strong>the</strong> injury but<br />

in all cases of trauma, <strong>the</strong> principal<br />

maxim is to fully elucidate <strong>the</strong> nature<br />

6<br />

APRIL 9 • 1999 OPTOMETRY TODAY


sponsored by<br />

Clinical decision making in ophthalmic emergencies<br />

DISTANCE LEARNING MODULE 1 PART 4<br />

and extent of any injury by adequate<br />

examination and to fully plan surgery or<br />

o<strong>the</strong>r management. In unco-operative<br />

patients (particularly in children) a<br />

general anaes<strong>the</strong>tic may be required. In<br />

o<strong>the</strong>r cases, unpreserved anaes<strong>the</strong>tic<br />

drops are considered safe following<br />

penetrating injury (and are used without<br />

retinal toxicity in ocular irrigating fluids<br />

during surgery) and may be used as<br />

required to facilitate examination. The<br />

risk of infection after penetrating injury<br />

is actually surprisingly small but <strong>the</strong><br />

administration of systemic antibiotics<br />

prior to surgery is <strong>the</strong> main adjunct.<br />

Topical antibiotics appear to convey no<br />

significant effect on reducing<br />

endophthmitis.<br />

Corneal abrasion<br />

This is excruciatingly painful in younger<br />

patients with symptoms out of<br />

proportion to <strong>the</strong> apparent injury.<br />

Always consider more serious injury and<br />

possible globe penetration during<br />

examination. Dilation of <strong>the</strong> pupil is an<br />

extremely effective analgesic and many<br />

authorities commend pressure patching<br />

until re-epi<strong>the</strong>lialisation has occurred<br />

with consequent reduction in pain. Do<br />

not patch an eye unless it is taped shut or<br />

a lubricated gauze is placed next to <strong>the</strong><br />

eye in case an abrasion is caused by <strong>the</strong><br />

dressing. Many patients find a pressure<br />

dressing uncomfortable and consider an<br />

unpatched eye preferable and use ice<br />

packs with some relief. Rarely <strong>the</strong><br />

epi<strong>the</strong>lium fails to heal in which case<br />

deliberate removal of <strong>the</strong> epi<strong>the</strong>lium to<br />

allow a fresh attempt is usually effective.<br />

Recurent corneal erosion<br />

This may follow an abrasion, sometimes<br />

months later, and presents typically with<br />

a patient awaking during REM sleep.<br />

Rapid eye movement is thought to<br />

spontaneously abrade <strong>the</strong> corneal<br />

epi<strong>the</strong>lium with similar extreme pain,<br />

although it is usually on a smaller scale<br />

and has often healed by <strong>the</strong> time <strong>the</strong><br />

patient is examined on a slit lamp with<br />

obvious diagnostic problems. Most cases<br />

resolve with <strong>the</strong> use of topical lubricants<br />

applied last thing at night or epi<strong>the</strong>lial<br />

debridement.<br />

Chemical injury<br />

Chemical injury requires an immediate<br />

response with removal of <strong>the</strong> material<br />

with forceps if appropriate followed by<br />

irrigation with saline or water. Topical<br />

anaes<strong>the</strong>sia should be used as required to<br />

permit examination and irrigation<br />

performed even if penetration is<br />

suspected. Do not accept any history of<br />

previous irrigation at <strong>the</strong> scene of <strong>the</strong><br />

accident as satisfactory - ALWAYS<br />

REPEAT IT YOURSELF<br />

IMMEDIATELY - 30 minutes with 1-2<br />

litres of saline or water is usually required<br />

to produce satisfactory results and <strong>the</strong><br />

lids must be everted to ensure that<br />

subtarsal remnants are not missed. Even<br />

where eyewash is available, it is only<br />

rarely in sufficient quantity to be<br />

effective. pH should be checked with<br />

particular caution being exercised if<br />

alkali injury is suspected (high pH) as<br />

alkali rapidly enters <strong>the</strong> anterior chamber<br />

with signs of ischaemia manifest as closed<br />

vessels at <strong>the</strong> limbus and corneal<br />

epi<strong>the</strong>lial loss.<br />

If syn<strong>the</strong>tic riot-control agents such<br />

as CS, mace or tear gas have been used,<br />

particular care must be exercised not to<br />

allow contact of health workers with <strong>the</strong><br />

clo<strong>the</strong>s of <strong>the</strong> victim as any remaining<br />

agent can be transmitted with disastrous<br />

results. Again, topical anaes<strong>the</strong>tic as<br />

required, ocular examination to<br />

determine injury followed by copious<br />

irrigation with water or saline, remains<br />

<strong>the</strong> recommended treatment. Pain,<br />

inflammation and secondary infection<br />

are treated with topical mydriatics,<br />

steroids and antibiotics as required. As<br />

soon as possible, ensure that no o<strong>the</strong>r<br />

ocular injury exists in conjunction.<br />

INFLAMMATORY AND<br />

ALLERGIC EMERGENCIES<br />

Hayfever and atopic disease<br />

Whilst not considered a serious<br />

condition, mild forms of allergy in <strong>the</strong> eye<br />

are common and constitute a significant<br />

workload to some practitioners. They are<br />

often associated with o<strong>the</strong>r allergies such<br />

as asthma and eczema. Severe forms are<br />

difficult to diagnose as <strong>the</strong>y may resemble<br />

more severe inflammatory conditions,<br />

particularly viral keratoconjunctivitis<br />

with corneal infiltrates but <strong>the</strong> absence of<br />

a swollen pre-auricular lymph node is an<br />

important diagnostic feature. Follicles<br />

(which are usually swollen to form ‘grains<br />

of rice’ in <strong>the</strong> tarsal conjunctiva in <strong>the</strong><br />

acute phase) and more superficial<br />

injection over <strong>the</strong> globe are also features<br />

of allergy. In extreme cases, lacrimation<br />

occurs under <strong>the</strong> conjunctiva with<br />

chemosis (Figure 12). Always check <strong>the</strong><br />

visual acuity and warn <strong>the</strong> patient to<br />

re-attend if symptoms persist or worsen.<br />

Figure 12<br />

Conjunctival chemosis in acute allergic eye disease<br />

Figure 13<br />

Acute iritis showing perilimbal injection<br />

Acute symptoms are best controlled with<br />

ice packs and topical antihistamines and<br />

mast-cell stabilisers with topical steroids<br />

reserved for more severe cases.<br />

Anterior uveitis<br />

This has several clinical appearances<br />

with variable amounts of fibrin (flare)<br />

and aggregations of leucocytes in <strong>the</strong><br />

aqueous (cells) (Figure 13). The history<br />

is usually of gradual increase in irritation,<br />

redness, photophobia and reduction in<br />

acuity. This can be over several days,<br />

weeks or may be of only a few hours. The<br />

long-term complications of acute<br />

anterior uveitis stem from <strong>the</strong> deposition<br />

of fibrin and subsequent scar formation<br />

in <strong>the</strong> trabecular meshwork to produce<br />

glaucoma. Adhesions between <strong>the</strong> iris<br />

and <strong>the</strong> anterior lens capsule produce<br />

synechiae with pupil distortion and<br />

obstruction of <strong>the</strong> flow of aqueous<br />

through <strong>the</strong> pupil with a risk of pupilblock<br />

glaucoma. Anterior uveitis,<br />

<strong>the</strong>refore, needs to be suppressed rapidly<br />

before <strong>the</strong>se changes become established.<br />

Firstline treatment is with frequent dose<br />

topical steroids and dilation of <strong>the</strong> pupil.<br />

APRIL 9 • 1999 OPTOMETRY TODAY 7


sponsored by<br />

Clinical decision making in ophthalmic emergencies<br />

DISTANCE LEARNING MODULE 1 PART 4<br />

Figure 14<br />

Mutton fat keratic precipitates in granulomatous<br />

uveitis. Associated systemic diseases need to be<br />

excluded<br />

In cases with a high fibrinous<br />

component, or in which synechiae have<br />

already formed, steroids and mydriatics<br />

may be given as a sub-conjunctival<br />

injection to maximise dosage. Intraocular<br />

pressure rises are usually managed with<br />

conventional topical glaucoma <strong>the</strong>rapy.<br />

As <strong>the</strong> uveitis comes under control,<br />

treatment is tapered but may need to be<br />

continued for weeks or months to avoid<br />

recurrences, which are relatively<br />

common. Unresponsive cases are<br />

infrequent but, occasionally, require<br />

systemic treatment with<br />

immunosuppressive drugs including<br />

steroids, azathioprine and cyclosporin<br />

(potent suppressers of T-lymphocyte<br />

activity, <strong>the</strong> leucocytes thought to<br />

control <strong>the</strong> underlying inflammatory<br />

process). Uncomplicated cases which<br />

respond rapidly to topical treatment are<br />

not usually extensively investigated but<br />

mutton-fat keratic precipitates of<br />

leucocytes (which are larger and more<br />

greasy in appearance) are particularly<br />

suggestive of an associated inflammatory<br />

condition (Figure 14).<br />

Posterior uveitis<br />

This tends to present with a more<br />

gradual onset than anterior uveitis with a<br />

gradual, painless impairment of vision<br />

and, in particular, <strong>the</strong> formation of<br />

floaters. It is potentially more serious as it<br />

may have been active longer prior to<br />

diagnosis and <strong>the</strong> retina is frequently<br />

directly involved with permanent visual<br />

impairment. Signs of active inflammation<br />

are chiefly <strong>the</strong> finding of small deposits of<br />

leucocytes in <strong>the</strong> vitreous and cases<br />

usually require prolonged and intensive<br />

management with systemic<br />

immunosuppressive drugs. There is a<br />

high incidence of associated diseases<br />

including Behçet’s disease, sarcoidosis<br />

and idiopathic retinal vasculitis which<br />

need to be considered.<br />

Episcleritis<br />

This presents with discomfort or usually<br />

mild pain in a watery red eye. There is<br />

usually no impairment of vision and<br />

injection is in a fairly discrete area with<br />

dilation of <strong>the</strong> finer, more superficial<br />

episcleral vessels and a slight blue-purple<br />

hue to <strong>the</strong> area. Although attacks are<br />

self-limiting and resolve without<br />

sequelae, topical steroids and oral<br />

flurbiprofen control symptoms and<br />

shorten attacks. A similar condition is an<br />

inflamed pingueculum in which an<br />

episcleitis-like condition is centered on a<br />

pre-existing pingueculum. This responds<br />

to similar treatment and also resolves<br />

without sequelae. Recurrence is common<br />

in both conditions.<br />

Scleritis<br />

This is usually painful and can be<br />

localised to a small, discrete area or be<br />

more extensive. Vision is usually<br />

unaffected and <strong>the</strong> condition is<br />

associated with o<strong>the</strong>r immune disorders<br />

including rheumatoid arthritis. A<br />

variant is posterior scleritis in which<br />

severe pain can be a feature in an eye<br />

which is not red. Secondary oedema may<br />

induce retinal changes with visual<br />

symptoms and occasionally proptosis or<br />

even optic nerve compression. Imaging<br />

with ultrasound, MRI or CT scan reveals<br />

thickening of <strong>the</strong> sclera. Treatment is<br />

systemic with oral non-steroidal antiinflammatory<br />

drugs (particularly<br />

Flurbiprofen and indomethacin). In<br />

severe cases oral and intravenous<br />

steroids and o<strong>the</strong>r immunosuppressives<br />

may be required.<br />

Optic neuritis<br />

Inflammation of <strong>the</strong> optic nerve is<br />

usually a part of a demyelinating disease<br />

(of which multiple sclerosis is <strong>the</strong> most<br />

common form). The visual loss occurs<br />

over a few days and is usually profound.<br />

It is associated in <strong>the</strong> initial stages with a<br />

reduction in sensitivity to red objects and<br />

an afferent pupil defect, and may be<br />

associated with active lesions elsewhere<br />

including <strong>the</strong> fellow optic nerve. If <strong>the</strong><br />

focal lesion is not close to <strong>the</strong> optic nerve<br />

head, <strong>the</strong>re may be no disc swelling or<br />

o<strong>the</strong>r signs of disease. Treatment is<br />

limited with high dose intravenous<br />

steroids used in severe cases but <strong>the</strong>se<br />

seem to offer little or no long-term<br />

benefit.<br />

INFECTIVE CONDITIONS<br />

Conjunctivitis<br />

Bacterial conjunctivitis may be identified<br />

by its mucoid or purulent discharge with<br />

little effect on <strong>the</strong> visual acuity. Most<br />

cases are self-limiting although cases<br />

caused by Neisseria or Chlamydia may be<br />

persistent and require systemic<br />

treatment for associated sites of infection<br />

(most commonly <strong>the</strong> genito-urinary<br />

tract). Viral conjunctivitis is associated<br />

with a watery discharge and follicles in<br />

<strong>the</strong> conjunctiva of <strong>the</strong> eyelids. A swollen<br />

pre-auricular lymph node (just in front<br />

of <strong>the</strong> ear on <strong>the</strong> affected side) is a<br />

common finding. Vision may be affected<br />

if <strong>the</strong> cornea is also involved, often in a<br />

characteristic pattern of sub-epi<strong>the</strong>lial<br />

opacities (e.g. in adenoviral<br />

keratoconjunctivitis). Most are thought<br />

to be spread by droplets from <strong>the</strong> nose<br />

and throat of infected individuals and<br />

epidemics are common. There is no<br />

specific treatment for viral infections<br />

(o<strong>the</strong>r than for herpes virus) and disease<br />

can continue for several weeks or even<br />

months. Whilst symptoms can be<br />

controlled by treatment with topical<br />

steroids, this is thought to prolong <strong>the</strong><br />

recovery time and is usually reserved for<br />

particularly severe cases. Topical<br />

antibiotics are often prescribed to reduce<br />

<strong>the</strong> risk of secondary bacterial infection<br />

but evidence for <strong>the</strong>ir effectiveness is<br />

poor.<br />

Keratitis (including<br />

acanthamoeba, bacterial<br />

and herpetic keratitis)<br />

This is characterised by pain, corneal<br />

infiltrate and epi<strong>the</strong>lial defect. The<br />

keratitis may be infectious (associated<br />

with contact lens use) although o<strong>the</strong>r<br />

conditions, including autoimmune<br />

disease, can cause severe keratitis.<br />

Whilst certain patterns of keratitis are<br />

diagnostic (such as herpetic),<br />

microbiological analysis of any infection<br />

from swabs and corneal scrapes guides<br />

subsequent intensive antibiotic<br />

treatment. Topical and/or systemic<br />

immunosuppression is usually required<br />

to control inflammatory causes.<br />

Orbital cellulitis,<br />

sinusitis and dacrocystitis<br />

Bacterial infections in sites adjacent to<br />

<strong>the</strong> orbit may lead to secondary infection<br />

and patients may present with proptosis<br />

and reduced ocular movements.<br />

Because of <strong>the</strong> associated swelling, <strong>the</strong>re<br />

is a risk that orbital pressure will rise with<br />

8<br />

APRIL 9 • 1999 OPTOMETRY TODAY


sponsored by<br />

Clinical decision making in ophthalmic emergencies<br />

DISTANCE LEARNING MODULE 1 PART 4<br />

optic nerve compression (see above). A<br />

broad-spectrum antibiotic in high dose<br />

is required but care must be exercised in<br />

dacrocystitis - if <strong>the</strong> sac is lanced or<br />

bursts through <strong>the</strong> skin of <strong>the</strong> cheek, a<br />

fistula may form requiring surgical<br />

correction.<br />

Herpes zoster (shingles)<br />

This is caused by reactivation of <strong>the</strong><br />

varicella-zoster virus (which causes<br />

chickenpox) which remains dormant in<br />

a sensory nerve root. Reactivation<br />

occurs in response to alteration in <strong>the</strong><br />

immune system with effects in <strong>the</strong><br />

anatomy supplied by <strong>the</strong> particular<br />

nerve involved. Globe and lid sensation<br />

is served by <strong>the</strong> ophthalmic and<br />

maxillary branches of <strong>the</strong> fifth cranial<br />

nerve and early symptoms are of altered<br />

sensation or pain over <strong>the</strong> area<br />

involved. Swelling and pain may<br />

precede <strong>the</strong> typical skin rash which<br />

produces weeping pustules and appears<br />

around four to seven days after initial<br />

symptoms. Conjunctivitis of<br />

predominantly <strong>the</strong> upper or lower lid,<br />

keratitis and scleritis are common<br />

features although intraocular<br />

involvement is not common. Entry to<br />

<strong>the</strong> eye requires involvement of a<br />

sensory branch, <strong>the</strong> naso-ciliary nerve.<br />

The presence of rash at <strong>the</strong> tip of <strong>the</strong><br />

nose (Hutchinson’s sign) should raise<br />

suspicions and suggest more frequent<br />

review as <strong>the</strong> uveitis produced can be<br />

insidious and asymptomatic until fairly<br />

advanced. Treatment is with specific<br />

anti-viral drugs to limit <strong>the</strong> replication<br />

of virus and shorten <strong>the</strong> attack. There is<br />

also some suggestion that prompt antiviral<br />

<strong>the</strong>rapy can reduce <strong>the</strong> incidence<br />

of post-herpetic neuralgia. In cases<br />

without intraocular involvement,<br />

recovery is straightforward but<br />

intraocular inflammation requires<br />

intensive topical treatment (see anterior<br />

uveitis) and is prone to relapse. Most<br />

cases require at least nine months of<br />

topical steroid drops.<br />

RETINAL AND DISC CONDITIONS<br />

Retinal detachment<br />

This often presents late and advanced<br />

with extensive peripheral field loss as it<br />

is not until <strong>the</strong>re is loss of macular<br />

function that <strong>the</strong> patient notices a<br />

definite symptom. Management is to<br />

close any retinal holes and relieve<br />

vitreous traction on <strong>the</strong> retina to allow<br />

re-attachment by external buckling of<br />

<strong>the</strong> sclera or by vitrectomy.<br />

Macular oedema<br />

This is a feature of a number of<br />

conditions including diabetes, various<br />

inflammatory conditions of <strong>the</strong> retina,<br />

scleritis and central serous<br />

chorioretinopathy. This causes a<br />

variable degree of visual distortion and<br />

loss of acuity. Treatment relates to <strong>the</strong><br />

diagnosis and may require laser<br />

photocoagulation of areas of capillary<br />

leakage.<br />

Hypertensive retinopathy<br />

Treatment is directed at <strong>the</strong><br />

hypertension or <strong>the</strong> cause of<br />

hypertension but cases are often those in<br />

which hypertension is secondary to o<strong>the</strong>r<br />

diagnoses and difficult to manage. The<br />

ocular problems tend to predispose<br />

towards a picture of vascular occlusion<br />

and disc swelling (Figure 15) but<br />

resolve when <strong>the</strong> blood pressure lowers.<br />

Unfortunately, <strong>the</strong> more severe cases<br />

often have a poor prognosis with<br />

multiple organ failure.<br />

Swollen optic discs - optic neuritis,<br />

intracranial hypertension<br />

Swollen discs may be due to a number of<br />

causes including optic nerve head drusen<br />

but, in <strong>the</strong> presence of visual reduction,<br />

headache and o<strong>the</strong>r symptoms, need to<br />

be considered as potentially due to a<br />

more serious pathological process. An<br />

MRI or CT of <strong>the</strong> brain and orbits will be<br />

required to exclude lesions of <strong>the</strong> optic<br />

nerves such as meningiomas,<br />

demyelinating disease or lesions in <strong>the</strong><br />

ventricular system of <strong>the</strong> brain. Lumbar<br />

puncture is often required to establish<br />

<strong>the</strong> pressure of cerebrospinal fluid and to<br />

examine it for <strong>the</strong> presence of<br />

inflammatory cells or proteins.<br />

OTHER CONDITIONS<br />

Glaucoma<br />

Acute closed angle glaucoma causes<br />

damage to <strong>the</strong> optic nerve and <strong>the</strong>re is a<br />

significant risk of secondary vascular<br />

occlusion. While intraocular pressure is<br />

high, little or no topical medication will<br />

enter <strong>the</strong> eye and intravenous or oral<br />

acetazolamide is required to cause initial<br />

pressure reduction. Pilocarpine and<br />

o<strong>the</strong>r topical glaucoma treatments are<br />

Figure 15<br />

Swollen optic disc in acute hypertensive<br />

retinopathy<br />

used <strong>the</strong>reafter. In <strong>the</strong> longer term, YAG<br />

or argon laser iridotomy or surgical<br />

iridectomy is <strong>the</strong> treatment of choice to<br />

maintain low pressure with a few<br />

patients requiring more extensive<br />

surgery because of irreversible damage to<br />

<strong>the</strong> angle. Treatment may be delayed<br />

until intraocular pressure is controlled by<br />

medical treatment, as oedema can make<br />

<strong>the</strong> cornea opaque to lasers and require<br />

excessive power to permit treatment.<br />

Thyroid eye disease<br />

Thyroid eye disease is generally a<br />

chronic problem in which <strong>the</strong> orbital fat<br />

swells and extraocular muscles fibrose.<br />

This can present with acute proptosis<br />

but less often presents as visual loss<br />

resulting from optic nerve compression.<br />

The condition is rare and requires<br />

systemic immunosuppression, X-ray<br />

treatment and, occasionally, surgery to<br />

<strong>the</strong> orbit to release <strong>the</strong> pressure.<br />

CONCLUSION<br />

The key to <strong>the</strong> optimum management of<br />

ocular emergencies lies in a careful<br />

assessment of <strong>the</strong> features of <strong>the</strong><br />

condition to suggest <strong>the</strong> general nature<br />

of <strong>the</strong> problem. This, in turn, will guide<br />

<strong>the</strong> initial management to allow<br />

appropriate investigations and basic<br />

treatment.<br />

ABOUT THE AUTHOR<br />

Adrian Parnaby-Price is a Fellow in Ocular Immunology at<br />

St Thomas’s Hospital, London, and a Specialist Registrar in<br />

Ophthalmology in <strong>the</strong> South-East Thames Region.<br />

APRIL 9 • 1999 OPTOMETRY TODAY 9


Multiple choice questions<br />

Clinical decision making in ophthalmic emergencies<br />

Please note <strong>the</strong>re is only ONE correct answer. An answer return form is included in this issue.<br />

It should be completed and returned to: CPD Initiatives (CDM4), <strong>Optometry</strong> <strong>Today</strong>,<br />

Victoria House, 178-180 Fleet Road, Fleet, Hampshire GU13 8DA, by May 5, 1999.<br />

1. Which one of <strong>the</strong> following<br />

statements is incorrect?<br />

Vitreous haemorrhage:<br />

a. may be associated with retinal<br />

detachment<br />

b. may be associated with posterior<br />

vitreous detachment<br />

c. may be caused by diabetic<br />

neovascular proliferation<br />

d. always causes a relative afferent<br />

pupillary defect<br />

2. Which one of <strong>the</strong> following<br />

statements is correct?<br />

A watery eye and palpable<br />

pre-auricular lymph node<br />

is a common feature of:<br />

a. adenoviral keratoconjunctivitis<br />

b. episcleritis<br />

c. chlamydial conjunctivitis<br />

d. staphylococcal conjunctivitis<br />

3. Which one of <strong>the</strong> following<br />

statements is incorrect?<br />

Orbital cellulitis:<br />

a. may be secondary to dacrocystitis<br />

b. may be secondary to sinusitis<br />

c. is usually viral in origin<br />

d. may present with proptosis, reduced<br />

ocular movements and optic nerve<br />

compression<br />

4. Which one of <strong>the</strong> following<br />

statements is incorrect?<br />

Floaters in <strong>the</strong> field of vision:<br />

a. are always associated with peripheral<br />

visual disturbance<br />

b. may be caused by a posterior<br />

vitreous detachment<br />

c. always require pupil dilation and<br />

comprehensive retinal examination<br />

d. may be caused by posterior uveitis<br />

5. Which one of <strong>the</strong> following<br />

statements is correct?<br />

a. Bilateral homonymous hemianopia in<br />

<strong>the</strong> central 15 degrees of vision may<br />

be caused by a temporal lobe<br />

cerebro vascular accident (CVA,<br />

stroke)<br />

b. Left superior homonymous<br />

quadrantanopia may be caused by a<br />

CVA in <strong>the</strong> right temporal lobe<br />

c. Superior altitudinal field loss in one<br />

eye may be due to a superior branch<br />

retinal artery occlusion<br />

d. Transient ischaemic attacks (TIAs)<br />

affecting <strong>the</strong> tip of <strong>the</strong> occipital lobe<br />

may leave a residual field defect<br />

affecting only <strong>the</strong> central visual field<br />

6. Which one of <strong>the</strong> following<br />

statements is incorrect?<br />

Alkali injury:<br />

a. causes <strong>the</strong> pH of intraocular fluids to<br />

fall within seconds of injury<br />

b. should be irrigated with at least 1 litre<br />

of saline or water<br />

c. is potentially more serious than an<br />

equivalent acid injury<br />

d. More serious injury may be<br />

presumed if <strong>the</strong>re is substantial<br />

epi<strong>the</strong>lial loss and ischaemia of <strong>the</strong><br />

limbal vessels in <strong>the</strong> acute phase.<br />

7. Which one of <strong>the</strong> following<br />

statements is correct?<br />

In anterior uveitis:<br />

a. mutton fat keratic precipitates do not<br />

require investigation for associated<br />

systemic conditions<br />

b. systemic immunosuppression is<br />

always required to allow adequate<br />

control of inflammation in <strong>the</strong><br />

long-term<br />

c. intraocular pressure can rise during<br />

acute attacks<br />

d. always gives rise to symptoms of<br />

red eye, photophobia and reduced<br />

vision<br />

8. Which one of <strong>the</strong> following<br />

statements is incorrect?<br />

The acute management of<br />

central retinal artery<br />

occlusion may include:<br />

a. urgent ESR and CRP<br />

b. anterior chamber paracentesis<br />

c. intravenous acetazolamide<br />

d. isovolaemic haemodilution<br />

9. Which one of <strong>the</strong> following<br />

statements is incorrect?<br />

Optic nerve compression:<br />

a. may be caused by thyroid eye<br />

disease<br />

b. causes reduction in sensitivity to red<br />

target late in disease<br />

c. causes loss of acuity late in<br />

disease<br />

d. is usually associated with<br />

increasing pain and reduction in<br />

ocular motility<br />

10. Which one of <strong>the</strong> following<br />

statements is correct?<br />

Relative afferent pupillary<br />

defect:<br />

a. is a feature of homonymous<br />

hemianopia<br />

b. is a common feature of a peripheral<br />

retinal detachment<br />

c. is always symptomatic<br />

d. may be present in an eye with a<br />

normal visual acuity<br />

11. Which one of <strong>the</strong> following<br />

statements is incorrect?<br />

Retinal detachment:<br />

a. is associated with vitreous<br />

haemorrhage<br />

b. is associated with posterior vitreous<br />

detachment<br />

c. may cause visual field loss<br />

d. causes early loss of acuity<br />

12. Which one of <strong>the</strong> following<br />

statements is incorrect?<br />

In central retinal artery occlusion,<br />

temporal arteritis:<br />

a. is associated with jaw claudication<br />

and proximal myopathy<br />

b. may have a good visual recovery<br />

if adequate treatment is given rapidly<br />

c. may require a biopsy<br />

for a satisfactory diagnosis<br />

to be made<br />

d. requires treatment with steroids<br />

for a year or more<br />

sponsored by<br />

Multiple choice answers<br />

Here are <strong>the</strong> correct answers to Part 3 of<br />

Module 1 on Clinical Decision Making,<br />

published on March 12, 1999.<br />

1. Which one of <strong>the</strong> following statements is correct<br />

regarding <strong>the</strong> symptoms and signs found in a<br />

posterior vitreous detachment (PVD)?<br />

a. Flashing lights signify a definite retinal tear<br />

b. Floaters and flashing lights are more serious than<br />

floaters alone<br />

c. Pigment cells in <strong>the</strong> anterior vitreous indicate a high<br />

risk of retinal pathology<br />

d. Floaters always signify a posterior vitreous<br />

detachment<br />

c is correct<br />

In a posterior vitreous detachment, <strong>the</strong> presence or<br />

absence of flashing lights, in addition to <strong>the</strong> floaters,<br />

makes no difference with regards to risk of a retinal tear.<br />

Few symptoms may indicate serious pathology.<br />

Examination of <strong>the</strong> anterior vitreous as it moves may<br />

indicate pigmented cells (Schaeffer’s sign) which are<br />

strongly suspicious of a retinal tear, or o<strong>the</strong>r cells<br />

suggesting inflammatory eye disease as <strong>the</strong> cause of<br />

floaters.<br />

2. Which one of <strong>the</strong> following<br />

statements is correct regarding central<br />

retinal vein occlusion (CRVO)?<br />

a. Sources of emboli need to be excluded<br />

b. May be caused by hypertension<br />

c. Requires urgent fluorescein angiography<br />

d. Often recovers good visual acuity if treated with<br />

pan-retinal photocoagulation<br />

b is correct<br />

Hypertension is <strong>the</strong> commonest association with a<br />

CRVO. O<strong>the</strong>r associations include elevated intraocular<br />

pressure and prothrombotic tendencies. Emboli cause<br />

arterial ra<strong>the</strong>r than venous occlusions. Fluorescein<br />

angiography may help determine if <strong>the</strong> CRVO is<br />

ischaemic or not, but is not urgent as <strong>the</strong> haemorrhages<br />

may obscure <strong>the</strong> fluorescence acutely and<br />

neovascularisation does not occur immediately. Visual<br />

prognosis after a CRVO is often poor.<br />

3. In <strong>the</strong> management of age-related macular<br />

degeneration (ARMD), which one of <strong>the</strong><br />

following statements is correct?<br />

a. Hard macular drusen signify high risk of sub-retinal<br />

neovascularisation<br />

b. Geographic atrophy requires argon laser<br />

photocoagulation<br />

c. Sudden metamorphopsia requires urgent referral<br />

d. Low vision aids do not benefit patients with<br />

sub-retinal neovascularisation<br />

c is correct<br />

Dry ARMD (drusen, pigmentary changes and<br />

geographic atrophy) is treated conservatively. It is<br />

known that large soft drusen carry a higher risk of subretinal<br />

neovascularisation, of which <strong>the</strong> earliest sign may<br />

be metamorphopsia. Urgent referral is required if a<br />

patient develops this for consideration of laser or o<strong>the</strong>r<br />

treatment. Patients at all stages of ARMD may benefit<br />

from low vision aids.<br />

4. Which one of <strong>the</strong> following statements is<br />

correct?<br />

Branch retinal artery occlusion (BRAO) -<br />

a. is a result of arteriovenous nipping<br />

b. is caused by chronic open angle glaucoma<br />

c. always results in loss of central vision<br />

d. is often due to an embolus<br />

d is correct<br />

10<br />

APRIL 9 • 1999 OPTOMETRY TODAY


sponsored by<br />

Clinical decision making in ophthalmic emergencies<br />

DISTANCE LEARNING MODULE 1 PART 4<br />

- Clinical management of retinal disorders<br />

A BRAO is usually <strong>the</strong> result of an embolus,<br />

ei<strong>the</strong>r from <strong>the</strong> carotid or cardiac circulation.<br />

AV nipping may result in a branch retinal vein<br />

occlusion as <strong>the</strong> hypertrophic artery wall<br />

compresses <strong>the</strong> vein as <strong>the</strong>y cross, and open<br />

angle glaucoma is a risk factor for a central<br />

retinal vein occlusion. The artery occlusion<br />

may affect central vision if it supplies <strong>the</strong><br />

macula, or may cause field loss if it supplies<br />

ano<strong>the</strong>r part of <strong>the</strong> retina.<br />

5. Which one of <strong>the</strong> following<br />

statements is correct?<br />

Epi-retinal membrane -<br />

a. always requires surgical correction<br />

b. may cause metamorphopsia<br />

c. is more common in men aged 20-45<br />

d. is always idiopathic<br />

b is correct<br />

An epiretinal membrane may cause<br />

metamorphopsia. It may be idiopathic,<br />

affecting people of both sexes in <strong>the</strong>ir 50s and<br />

60s, or be due to o<strong>the</strong>r retinal problems such<br />

as post retinal detachment surgery and<br />

cryo<strong>the</strong>rapy. It often stabilises and, <strong>the</strong>refore,<br />

may require no treatment.<br />

6. Which one of <strong>the</strong> following retinal<br />

disorders does not present with<br />

floaters?<br />

a. Toxoplasmosis<br />

b. Posterior vitreous detachment<br />

c. Amaurosis fugax<br />

d. Intermediate uveitis<br />

c is correct<br />

The causes of floaters include a posterior<br />

vitreous detachment and inflammatory eye<br />

disease, such as toxoplasmosis and<br />

intermediate uveitis affecting one or both eyes.<br />

Amaurosis fugax causes a transient loss of<br />

vision lasting up to 10 minutes, affecting one<br />

eye.<br />

7. Which one of <strong>the</strong> following<br />

statements is correct regarding<br />

<strong>the</strong> management of retinal tears?<br />

a. A retinal tear associated with a retinal<br />

detachment will always be treated with<br />

argon laser only<br />

b. There is always a single retinal tear<br />

after a posterior vitreous detachment<br />

c. Retinal tears may be anterior to <strong>the</strong><br />

equator and not visible on slit lamp<br />

biomicroscopy<br />

d. Retinal tears are not treated with<br />

cryo<strong>the</strong>rapy<br />

c is correct<br />

Retinal tears in association with a posterior<br />

vitreous detachment may be anterior to <strong>the</strong><br />

equator of <strong>the</strong> retina and require indirect<br />

ophthalmoscopy with indentation to see. They<br />

may be multiple and can be treated with laser<br />

or cryo<strong>the</strong>rapy. However, if <strong>the</strong>re is an<br />

associated retinal detachment, laser is usually<br />

inadequate and <strong>the</strong>y require detachment<br />

surgery to flatten <strong>the</strong> detachment and to allow<br />

<strong>the</strong> laser or cryo<strong>the</strong>rapy to ‘seal’ <strong>the</strong> tear.<br />

8. Which one of <strong>the</strong> following<br />

statements is correct?<br />

Macular holes -<br />

a. affect men more commonly than<br />

women<br />

b. may be bilateral<br />

c. require laser treatment<br />

d. often follow on from retinal detachment<br />

surgery or cryo<strong>the</strong>rapy<br />

b is correct<br />

Macular holes typically affect postmenopausal<br />

women and are said to be<br />

bilateral in 10%. They are usually primary or<br />

idiopathic (that is not associated with o<strong>the</strong>r<br />

retinal disease) and may require surgery in<br />

<strong>the</strong> form of vitrectomy and intraocular gas<br />

injection to flatten <strong>the</strong>m.<br />

9. Which one of <strong>the</strong> following<br />

statements is correct?<br />

Acute central retinal artery occlusion -<br />

a. is treated with intravenous steroids<br />

b. requires attempts to lower <strong>the</strong> intraocular<br />

pressure<br />

c. always requires laser treatment to prevent<br />

neovascularisation<br />

d. subsequently results in a cupped optic<br />

disc<br />

b is correct<br />

Treatment for a central retinal artery occlusion<br />

is often disappointing, but attempts are made<br />

to move <strong>the</strong> embolus down <strong>the</strong> arterial tree by<br />

acutely lowering <strong>the</strong> intraocular pressure<br />

using ocular massage and intravenous<br />

acetazolamide (diamox). It does not require<br />

laser treatment (unless rubeosis occurs) and<br />

usually results in optic atrophy and severely<br />

reduced vision.<br />

10. Which one of <strong>the</strong> following<br />

statements is correct?<br />

Photopsia (flashing lights) -<br />

a. last less than 10 minutes in a migraine<br />

attack<br />

b. are usually bilateral in migraine<br />

c. are homonymous in posterior vitreous<br />

detachment<br />

d. are associated with o<strong>the</strong>r symptoms in<br />

vertebrobasilar disease<br />

b is correct<br />

Photopsia in migraine last 10-30 minutes and<br />

are usually homonymous and, <strong>the</strong>refore,<br />

affect both eyes even though most patients<br />

will describe <strong>the</strong>m as unilateral. In posterior<br />

vitreous detachment, <strong>the</strong>y are unilateral and<br />

occur as flickers lasting a few seconds just in<br />

<strong>the</strong> temporal field of vision in dim light.<br />

Photopsia are not usually associated with<br />

vertebrobasilar disease and would occur with<br />

o<strong>the</strong>r symptoms such as vertigo and drop<br />

attacks.<br />

11. Which one of <strong>the</strong> following<br />

statements is correct regarding<br />

hypertensive retinal<br />

changes?<br />

a. Venous beading and venous<br />

looping are signs of accelerated<br />

hypertension<br />

b. AV nipping occurs as a result of<br />

hypertrophy of <strong>the</strong> vein wall due<br />

to <strong>the</strong> hypertension<br />

c. Swollen discs, haemorrhages and<br />

exudates indicate a dangerous<br />

level of blood pressure<br />

d. Silver-wiring is <strong>the</strong> earliest sign<br />

of hypertension<br />

c is correct<br />

Accelerated hypertension, in which swollen<br />

discs, haemorrhages, cotton wool spots and<br />

exudates are seen, indicates a sudden<br />

severe elevation in blood pressure and<br />

patients require urgent admission for<br />

treatment and to establish <strong>the</strong> cause, which is<br />

often renal disease. The changes of chronic<br />

essential hypertension include narrowed and<br />

straightened arterioles and AV nipping in<br />

which <strong>the</strong> thickened artery wall compresses<br />

<strong>the</strong> vein as <strong>the</strong>y cross. Silver-wiring is not a<br />

good sign of hypertension.<br />

12. Which one of <strong>the</strong> following does not<br />

require laser treatment?<br />

a. A retinal hole<br />

b. Central retinal vein occlusion<br />

c. Branch retinal artery occlusion<br />

d. Sub-retinal neovascular<br />

membrane<br />

c is correct<br />

Argon laser photocoagulation may be<br />

required to seal around a retinal tear or hole,<br />

to ablate a sub-retinal neovascular membrane<br />

or to prevent rubeosis with pan-retinal<br />

photocoagulation in an ischaemic central<br />

retinal vein occlusion. It is not normally<br />

required in a branch retinal artery occlusion<br />

as <strong>the</strong> retina distal to this is infarcted, not<br />

ischaemic.<br />

APRIL 9 • 1999 OPTOMETRY TODAY 11

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!