Evaluation of optic disc in glaucoma

ادخ مانب
evaluation of optic disc in glaucoma

Early diagnosis is important (in asymptomatic stage)
There is shortcoming in glaucoma diagnosis
Disc evaluation is very useful for early diagnosis and
monitoring progression(functional test are time
consuming and patients are meny)
Different method exist none of them is widely accepted

Different new imaging
not better than clinical evaluation of the optic disc and
peripapillary retinal nerve fiber layer.
Provides the most reliable early evidence of glaucoma
Frequently structure function(visual field)

Recent studies have shown the difficulty clinicians have: in
following adequate guidelines that recommend documentation of the optic disc appearance at
the time of diagnosis and at periodic intervals during follow-up
Due to a biologic overlap : almost all quantitative variables between normal
subjects and glaucoma patients, qualitative variables have a higher
specificity in separating glaucomatous from normal eyes.

رد و دوش راذگاو فلتخم یاھتست هب دناوت یم هن موکولگ صيخشت نياربانب
تانياعم رد یراميب فشک و کشزب مشچ هب راميب هعجارم رضاح لاح
.
تسا یراميب اب هلباقم هاراھنت

The mechanical theory of glaucoma postulates

1. As a thorough optic nerve examination is incorporated into clinical practice, it can be used along with
perimetry to allow early glaucoma diagnosis and also to assess disease severity.
2. Staging the disease and consideration of risk factors for glaucoma progression
enables the clinician
3. to establish a target intraocular pressure.
4. The structural assessment (optic nerve/RNFL) and functional evaluation (perimetry) are used together to
monitor for change as well restage the patient’s condition

a systematic approach for the evaluation of the optic disc
and RNFL in glaucoma that
FORGE (Focusing Ophthalmology on Reframing
FORGE (Focusing Ophthalmology on Reframing
Glaucoma Evaluation)

a systematic approach
for the evaluation of the optic disc and RNFL in
glaucoma
The five rules (5Rs) for the assessment of the
optic disc in glaucoma include:
1. Observe the scleral Ring to identify the limits of the optic disc
and evaluate its size.
2. Identify the size of the neuroretinal Rim.
3. Examine the Retinal nerve fiber layer.
4. Examine the Region outside the optic disc for parapapillary
atrophy.
5. Watch for Retinal and optic disc hemorrhages

A systematic process enhances the ability to detect glaucomatous
damage as well as the detection of progression, and facilitates
appropriate management.
An optic nerve or RNFL abnormality
is often, but not always, the first sign of
glaucomatous damage.1,2
no systematic approach for optic disc examination
in glaucoma has been widely disseminated.
When examining a patient who either has
established glaucoma or is suspected of having
the disease, a systematic approach to optic disc
and RNFL examination is necessary so that glaucomatous
optic neuropathy is not overlooked.

Methodology
The five rules (5Rs) for the assessment of the
optic disc in glaucoma include:
1. Observe the scleral Ring to identify the
limits of the optic disc and evaluate its size.
2. Identify the size of the Rim.
3. Examine the Retinal nerve fiber layer.
4. Examine the Region outside the optic disc
for parapapillary atrophy.
5. Watch for Retinal and optic disc hemorrhages

1-scleral Ring :optic disc size
Caucasians have relatively small optic discs, followed
by Mexicans, Asians, and Afro-Americans
correlated with the size of the optic cup and
neuroretinal rim
large cups, - erroneous diagnosis of glaucoma
small cups can be glaucomatous in small discs- may be
underdiagnosed
vertical disc diameter : 2.2mm

Correction factors are needed
(1.0 for 60 D lens,
1.1 for 78D lens and
1.3 for 90D lens)
EXAMPLE: 2.6/1.3=2

2. Identify the width and shape of the
Rim
The rim width
The rim shape:
‘ISNT rule’ :not obey the ISNT rule, glaucomatous damage
must be suspected
the color of the Rim .
Pallor of the rim :likelihood of a nonglaucomatous optic
neuropathy(especially when pallor is greater than cup
size.)

ISNT rule

37.8% of normal
eyes

3-Examine the Retinal nerve fiber layer
If using the slit lamp and fundus lens, magnification is reduced to 6 to 10x while using a 78D
or 90D lens and red-free or green light.
RNFL defects may also be visible in white light. In a healthy eye, bright striations are visible,
and the retina glistens in the regions in which the RNFL is thickest, superior temporal and
inferior temporal from the disc.20-22
The examiner should observe the brightness and striations of the RNFL as well as the
visibility of the parapapillary vessels.
RNFL loss can occur in a diffuse, localized, or mixed pattern.
With diffuse loss, there is general reduction of the RNFL brightness, with reduction of the
difference normally occurring between the superior and inferior poles when compared with
the temporal and nasal regions. (see Figure 11).
Localized:follow an arcuate pattern- True RNFL defects are at least an arteriole in width and
extend back to the optic disc compared with pseudodefects, which may be thin or never
extend to the optic nerve.

3-Examine the Retinal
nerve fiber layer
Not pathognomonic for glaucoma
Localized RNFL loss occurs in
about 20% or more of all
glaucomatous eyes

Rule 4: Parapapillary
atrophy (PPA) refers to the thinning and degeneration
of the chorioretinal tissue just outside of
the optic disc, which has an association with
development and progression of glaucoma.
Zone is present in most normal eyes as well as in eyes with
glaucoma -The
more important zone with regard to glaucoma is
zone ,
If both areas are present,
Zone α is always peripheral to the zone β. Zone β
is more common and extensive in eyes with
glaucoma than in healthy eyes. The area of PPA
is spatially correlated with the area of neuroreti

4-Peripapillary Region for parapapillary
(PPA)
the peripapillary chorioretinal atrophy can be divided
into a
Central band a peripheral a

a variable of second order
α β
in eyes with small optic
discs
in eyes with high myopia and in eyes with tilted optic discs

5-Retinal and optic disc hemorrhages
indicate that the condition is not
stable
feathery shape-at the level of the
lamina cribrosa
transient and usually visible for 1–6
• near blood vessels making its
detection difficult
• usually located in the inferior
• usually located in the inferior
temporal or superior temporal
regions
• association with notching
• more common in normal tension
glaucoma
• 4–7% of eyes with glaucoma, Rarely or
very rarely found in normal eyes

Association of findings and comparison
with the opposite eye
1. the combination of findings leads to stronger evidence of
the disease
2. An asymmetry of the cup–disc ratio greater than 0.2
2. An asymmetry of the cup–disc ratio greater than 0.2
between eyes or the ISNT rule.

Several cases are provided to allow the reader to
go through the 5 Rs checklist and determine
whether glaucoma is present (see Figures 17, 18,
19, and 20). Each example illustrates a different
way glaucoma may present
By following these 5 rules, a
thorough and systematic review of the optic disc
and RNFL will occur. This will improve the
ability to diagnosis and manage glaucoma