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Peter G. Swann BSc (Hons), MAppSc, FCOptom, FAAO and Katrina L. Schmid BAppSc (Optom) (Hons), GradCertEd (Higher Ed), PhD<br />

Fundus changes in myopia<br />

An overview<br />

Myopia is <strong>the</strong> most common of <strong>the</strong><br />

refractive errors. Due to this, and <strong>the</strong><br />

fact that many patients have a<br />

relatively low degree of myopia, with<br />

no deleterious ocular changes, <strong>the</strong>re<br />

is perhaps a tendency to regard<br />

myopia as a simple refractive<br />

condition without considering <strong>the</strong><br />

serious visual problems which can<br />

arise. This article describes <strong>the</strong><br />

changes which can occur in <strong>the</strong><br />

ocular fundus due to axial myopia. A<br />

treatment to slow or arrest <strong>the</strong> axial<br />

elongation of <strong>the</strong> eye and, thus, <strong>the</strong>se<br />

complications is required. Band-aid<br />

approaches such as spectacles or<br />

refractive surgery, which do not<br />

prevent <strong>the</strong> elongation of <strong>the</strong> eye, will<br />

have no beneficial effect in terms of<br />

preventing such consequences.<br />

Figure 1<br />

Optic disc crescents are common in<br />

myopes. They can vary in size and location<br />

but are typically situated at <strong>the</strong> temporal<br />

disc margin as in this three dioptre myope.<br />

Figure 2<br />

A much larger crescent in a nine dioptre<br />

myope<br />

The extent to which members of a<br />

population are myopic varies between races. In<br />

<strong>the</strong> United States and o<strong>the</strong>r Western countries,<br />

about a quarter of <strong>the</strong> population are myopic<br />

by <strong>the</strong>ir late teens 1 with this figure rising to<br />

approximately one third by 40 years of age.<br />

Many people experience a slight decrease in<br />

<strong>the</strong>ir level of myopia after about 45 years of<br />

age, most likely due to decreased power of <strong>the</strong><br />

crystalline lens 2 .<br />

The prevalence of myopia is dramatically<br />

higher in many Asian races, Jewish and Arabic<br />

people, and also tends to be more severe. The<br />

reasons for this are not known, with both<br />

genetic and environmental factors being<br />

suggested 3,4 . While approximately one quarter<br />

to one third of <strong>the</strong> myopic population has a<br />

degree of myopia greater than six dioptres, <strong>the</strong><br />

prevalence of severe myopia is likely to be<br />

higher in <strong>the</strong>se countries 4 . It is probable that<br />

<strong>the</strong> prevalence and severity of myopia is<br />

increasing worldwide as, <strong>the</strong>refore, will its<br />

public health impact 5 .<br />

Pathological myopia has a prevalence of<br />

about 2% in <strong>the</strong> USA and is <strong>the</strong> seventh<br />

leading cause of blindness in that country 6 .<br />

Figures from Canada, albeit somewhat dated,<br />

indicated that 9% of blindness was due to<br />

pathological myopia 7 .<br />

Pathological myopia usually refers to a<br />

condition where <strong>the</strong>re is greater than six<br />

dioptres of myopia or an axial length greater<br />

than 26-27mm 8 . It is a progressive, probably<br />

autosomal recessive disorder where serious<br />

ocular complications can develop such as<br />

chorioretinal degeneration, posterior<br />

staphyloma, retinal detachment, primary open<br />

angle glaucoma and posterior subcapsular and<br />

nuclear cataract. Highly myopic eyes also have<br />

greater responsiveness to topical<br />

corticosteroids and, <strong>the</strong>refore, <strong>the</strong>re is a<br />

higher risk of raised intraocular pressure (IOP)<br />

with <strong>the</strong>ir prolonged use 9 .<br />

Fur<strong>the</strong>rmore, o<strong>the</strong>r ocular and general<br />

conditions or diseases can be associated with<br />

pathological myopia. Some examples include<br />

retinitis pigmentosa, ocular albinism, infantile<br />

glaucoma, retinopathy of prematurity, Down’s<br />

syndrome, Marfan’s syndrome, Ehlers-Danlos<br />

syndrome and Sticklers syndrome 6,10 .<br />


In this review, we have divided ocular fundus<br />

changes in terms of <strong>the</strong>ir location, that is, <strong>the</strong><br />

posterior pole or <strong>the</strong> fundus periphery. A brief<br />

summary is given in Table 1 (page 35).<br />

Blacharski 7 divides chorioretinal changes in<br />

myopia into biomechanical, neovascular and<br />

degenerative types. Biomechanical changes<br />

include <strong>the</strong> so-called “lacquer cracks”, where<br />

fractures or tears occur in Bruch’s membrane,<br />

and posterior staphylomas. Choroidal<br />

neovascularisation can arise, usually in older<br />

myopes, and resolution may be seen in <strong>the</strong><br />

form of a Fuchs’ spot. Various degenerative<br />

changes are common such as chorioretinal<br />

atrophy, lattice degeneration and pavingstone<br />

degeneration.<br />


Optic disc crescent<br />

This is an early change in <strong>the</strong> myopic fundus<br />

and is due to a pulling away of <strong>the</strong> choroid and<br />

pigment epi<strong>the</strong>lium, usually from <strong>the</strong> temporal<br />

edge of <strong>the</strong> nerve to expose <strong>the</strong> sclera<br />

(Figure 1). Curtin and Karlin 11 found optic disc<br />

crescents in all eyes which had an axial length<br />

of 28.5mm or more. Temporal and annular<br />

crescents predominated. O<strong>the</strong>r studies have<br />

found that <strong>the</strong> width of <strong>the</strong> crescent was<br />

strongly associated with <strong>the</strong> degree of myopia<br />

(Figure 2).<br />

Research on Chinese subjects in Hong Kong<br />

has provided fur<strong>the</strong>r insights 12,13 . Whereas <strong>the</strong><br />

incidence of crescent formation was<br />

significantly associated with increasing axial<br />

length and myopic refraction, when acquired<br />

ra<strong>the</strong>r than physiological crescents were<br />

considered, <strong>the</strong> size of <strong>the</strong> crescent was not<br />

related to increased axial length or myopic<br />

refraction. Also, optic discs were more<br />

vertically oval in highly myopic eyes – a factor<br />

which must be considered when examining <strong>the</strong><br />

optic disc of a myope who is also a glaucoma<br />

suspect, glaucoma being certainly more<br />

common in myopic eyes, especially <strong>the</strong> high<br />

myopes 14 . Appropriate assessment of <strong>the</strong> optic<br />

disc cup can be a challenge in <strong>the</strong> myope,<br />

particularly when <strong>the</strong> optic disc is tilted and a<br />

crescent or zone of peripapillary atrophy is<br />

present. In <strong>the</strong> moderate myope, <strong>the</strong> cup to<br />

disc ratio may be greater than average,<br />

whereas <strong>the</strong> higher myopes may appear to have<br />

little cup because of posterior staphyloma<br />

formation. A stereoscopic evaluation through<br />

dilated pupils is, <strong>the</strong>refore, mandatory.<br />

Posterior staphyloma<br />

A posterior staphyloma is a backward ectasia<br />

of <strong>the</strong> fundus, <strong>the</strong> hallmark being tessellation<br />

and pallor of <strong>the</strong> area involved (Figure 3). The<br />

edges of <strong>the</strong> staphyloma may be anything but<br />

discrete. Curtin 15 divides staphylomas into five<br />

types, with <strong>the</strong> first, where <strong>the</strong> area of<br />

tessellation and pallor includes <strong>the</strong> region of<br />

<strong>the</strong> optic disc and macula, being <strong>the</strong> most<br />

common. Type two tends to encompass <strong>the</strong><br />

region of <strong>the</strong> macula, type three is<br />

peripapillary and type four extends nasally<br />

from <strong>the</strong> optic disc. The fifth type is <strong>the</strong> most<br />

rare and involves <strong>the</strong> fundus inferior to <strong>the</strong><br />

optic disc. Posterior staphylomas are often<br />

www.optometry.co.uk<br />


ot<br />

Figure 3<br />

The most common type 1 posterior<br />

staphyloma. The edge of <strong>the</strong><br />

staphylomatous region is arrowed<br />

progressive and result in vision loss 16 .<br />

Steidl and Pruett 17 found that eyes with <strong>the</strong><br />

shallowest staphylomas showed <strong>the</strong> largest<br />

drop in visual acuity as well as <strong>the</strong> greatest<br />

frequency of choroidal neovascular membranes<br />

and haemorrhage. They suggested that with<br />

less advanced staphylomas, <strong>the</strong> choriocapillaris<br />

was better preserved, thus increasing <strong>the</strong><br />

likelihood of <strong>the</strong> development of neovascular<br />

membranes.<br />

Lacquer cracks<br />

Lacquer cracks, thought to be healed linear<br />

ruptures in <strong>the</strong> retinal pigment epi<strong>the</strong>lium-<br />

Bruch’s membrane-choriocapillaris complex 18 ,<br />

are present in about 4% of highly myopic eyes 19<br />

(Figure 4). They are frequently seen in<br />

conjunction with posterior staphylomas and up<br />

to a third can have associated neovascular<br />

membranes. The resolution of any resultant<br />

haemorrhage may lead to <strong>the</strong> formation of a<br />

pigmented Fuchs’ spot (Figure 5). Lacquer<br />

cracks often progress to form more advanced<br />

fundus changes 19 . Patients with lacquer cracks<br />

and/or Fuchs’ spot should receive a guarded<br />

prognosis for vision.<br />

Chorioretinal atrophy<br />

More commonly seen in <strong>the</strong> younger myope,<br />

<strong>the</strong>se areas appear as small, punched-out<br />

yellow/white lesions in <strong>the</strong> presence of<br />

posterior staphylomas, and potentially close to<br />

lacquer cracks and <strong>the</strong> macula (Figure 6). With<br />

time, smaller lesions frequently coalesce to<br />

form larger areas 20 (Figure 7). Chorioretinal<br />

atrophy may be <strong>the</strong> result of stretching and<br />

thinning of <strong>the</strong> retinal pigment epi<strong>the</strong>lium and<br />

choroid as <strong>the</strong> eye enlarges, thus exposing <strong>the</strong><br />

sclera 21 .<br />


The major threat to vision in <strong>the</strong> myopic eye is<br />

retinal detachment, especially as posterior<br />

vitreous detachment (PVD) and predisposing<br />

retinal degenerations, such as lattice<br />

degeneration, are more common in <strong>the</strong>se eyes.<br />

Figure 4<br />

Lacquer cracks near <strong>the</strong> macula<br />

Akiba 22 suggested that in high myopia, PVD<br />

develops increasingly with age and <strong>the</strong> degree<br />

of myopia, and that it may be seen as much as<br />

10 years earlier in highly myopic eyes<br />

compared to emmetropic eyes. In a study of<br />

218 patients with myopia of six dioptres or<br />

more in both eyes, Celorio and Pruett 23 found<br />

that one third had lattice degeneration, with<br />

<strong>the</strong> greatest prevalence being in eyes having<br />

six to nine dioptres of myopia. Lattice<br />

degeneration represents vulnerable areas of<br />

retinal thinning. It is non-age specific and is<br />

seen in about 40% of eyes with retinal<br />

detachment 9 .<br />

Pigmentary degeneration, consisting of<br />

extensive pigment deposition in <strong>the</strong> extreme<br />

retinal periphery, and <strong>the</strong> non-predisposing<br />

paving stone degeneration (yellow-white areas<br />

of chorioretinal thinning) are also more<br />

common in myopic eyes. The pigment<br />

proliferation and RPE migration of pigmentary<br />

degeneration may be due to retinal traction,<br />

while <strong>the</strong> chorioretinal thinning in paving<br />

stone degeneration may be due to localised<br />

occlusion of <strong>the</strong> choroidal circulation 16 . White<br />

without pressure (translucent whitish<br />

Figure 6<br />

Chorioretinal atrophy: small, punched out<br />

lesions near <strong>the</strong> macula (<strong>the</strong> white streak at<br />

<strong>the</strong> bottom of <strong>the</strong> photograph is artefact)<br />

Figure 5<br />

A developing Fuchs’ spot toge<strong>the</strong>r with<br />

haemorrhage and a serous detachment of<br />

<strong>the</strong> macula. Vision was markedly reduced<br />

circumferential patches), from a prominent<br />

vitreous base and mild vitreous traction, is<br />

more frequently seen in myopic eyes and<br />

occasionally retinal breaks can occur in <strong>the</strong><br />

presence of such lesions 9,16 .<br />

It has been estimated that potentially up to<br />

80% of eyes suffering retinal detachment have<br />

some degree of myopia. Also, a person with<br />

five dioptres of myopia is at a 15 times greater<br />

risk of developing retinal detachment than an<br />

emmetrope. With 20 dioptres of myopia, <strong>the</strong><br />

risk increases to 110 times 7 . There are also<br />

reports of retinal detachments in myopes<br />

following clear lens extraction procedures used<br />

to refractively correct <strong>the</strong> myopia 24 .<br />


Myopic patients, especially those with<br />

pathological myopia, must be reviewed<br />

regularly, preferably on an annual basis, and<br />

always through dilated pupils. They should<br />

receive appropriate warnings of signs<br />

and symptoms that may indicate a<br />

sight-threatening situation is developing,<br />

and be advised to utilise protective eyewear in<br />

Figure 7<br />

Chorioretinal atrophy: larger geographic<br />

areas involving <strong>the</strong> posterior pole<br />

34<br />

March 22, 2002 OT<br />


potentially hazardous circumstances. Patients<br />

at risk for subretinal neovascular membrane<br />

formation should be given a take-home Amsler<br />

grid for daily testing. The increased incidence<br />

of associated conditions, such as glaucoma,<br />

must be remembered.<br />

About <strong>the</strong> authors<br />

Peter Swann is Associate Professor and<br />

Katrina Schmid Senior Lecturer in <strong>the</strong> School<br />

of Optometry, Queensland University of<br />

Technology, Brisbane, Australia. Professor<br />

Swann has a particular interest in eye disease,<br />

and Dr Schmid in <strong>the</strong> aetiology of myopia.<br />

References<br />

1. Sperduto RD, Seigel D, Roberts J, Rowland<br />

M. (1983) Prevalence of myopia in <strong>the</strong><br />

United States. Arch. Ophthalmol. 101:<br />

405-407.<br />

2. Lee KE, Klein BEK, Klein R. (1999) Changes<br />

in refractive error over a 5-year interval in<br />

<strong>the</strong> Beaver Dam Eye study. Invest<br />

Ophthalmol. Vis. Sci. 40: 1645-1649.<br />

3. Wu MM, Edwards MH. (1999) The effect of<br />

having myopic parents: an analysis of<br />

myopia in three generations. Optom. Vis.<br />

Sci. 76: 387-392.<br />

4. Wu HM, Seet B, Yap EP et al. (2001) Does<br />

education explain ethnic differences in<br />

myopia prevalence? A population-based<br />

study of young adult males in Singapore.<br />

Optom. Vis. Sci. 78: 234-239.<br />

5. Rose K, Smith W, Morgan I, Mitchell P.<br />

(2001) The increasing prevalence of<br />

myopia: implications for Australia.<br />

Clin. Exp. Ophthalmol. 29: 116-120.<br />

6. Alexander LJ. (1994) Primary care of <strong>the</strong><br />

posterior segment. Appleton & Lange,<br />

Connecticut.<br />

7. Blacharski PA. (1988) Pathologic<br />

progressive myopia, in DA Newsome Ed.,<br />

Retinal dystrophies and degenerations.<br />

Raven Press, New York.<br />

8. Miller DG, Singerman LJ. (2001) Natural<br />

history of choroidal neovascularization in<br />

high myopia. Curr. Opinion Ophthalmol.<br />

12: 222-224.<br />

9. Kanski JJ. (1994) Clinical Ophthalmology<br />

3rd ed, Butterworth-Heinemann, Oxford.<br />

10. Marr JE, Halliwell-Ewen J, Fisher B et al.<br />

(2001) Associations of high myopia in<br />

childhood. Eye 15: 70-74.<br />

11. Curtin BJ, Karlin DB. (1971) Axial length<br />

measurements and fundus changes of <strong>the</strong><br />

myopic eye. Am. J. Ophthalmol. 71: 42-53.<br />

12. Hendicott P, Lam C. (1991) Myopic<br />

crescent, refractive error and axial length<br />

in Chinese eyes. Clin. Exp. Optom. 74: 168-<br />

174.<br />

13. Lam AKC, Cheng KKH, Lam RK et al. (1996)<br />

Optic disc ovalness, refractive error and<br />

axial length of Hong Kong Chinese.<br />

Clin. Exp. Optom. 79: 167-172.<br />

14. Mitchell P, Hourihan F, Sandbach J, Wang<br />

JJ. (2000) The relationship between<br />

glaucoma and myopia. Ophthalmology 106:<br />

2010-2015.<br />

15. Curtin BJ. (1977) The posterior staphyloma<br />

of pathologic myopia.<br />

Trans. Am. Ophthalmol. Soc. 75: 67-86.<br />

16. Hoffman DJ, Heath DA. (1987) Staphyloma<br />

and o<strong>the</strong>r risk factors in axial myopia.<br />

J. Am. Optom. Assoc. 58: 907-913.<br />

17. Steidl SM, Pruet RC. (1997) Macular<br />

complications associated with posterior<br />

staphyloma. Am. J. Ophthalmol. 123:<br />

181-187.<br />

18. Klein RM, Curtin BJ. (1975) Lacquer crack<br />

lesions in pathologic myopia.<br />

Am. J. Ophthalmol. 79: 386-392.<br />

19. Ohno-Matsui K, Tokoro T. (1996) The<br />

progression of lacquer cracks in pathologic<br />

myopia. Retina 16: 29-37.<br />

20. Ito-Ohara M, Seko Y, Morita H et al. (1998)<br />

Clinical course of newly developed or<br />

progressive patchy chorioretinal atrophy in<br />

pathological myopia. Ophthalmologica<br />

212: 23-29.<br />

21. Morse PH. (1989) Vitreoretinal disease 2nd<br />

ed, Year Book Medical Publishers, Chicago.<br />

22. Akiba J. (1993) Prevalence of posterior<br />

vitreous detachment in high myopia.<br />

Ophthalmology 100: 1384-1388.<br />

23. Celorio JM, Pruett RC. (1991) Prevalence of<br />

lattice degeneration and its relation to<br />

axial length in severe myopia.<br />

Am. J. Ophthalmol. 111: 20-23.<br />

24. Ripandelli G, Billi B, Fedeli S. (1996)<br />

Retinal detachment after clear lens<br />

extraction in 41 eyes with high axial<br />

myopia. Retina 16: 3-6.<br />

25. Pierro L, Camesasca FI, Mischi M, Brancato<br />

R. (1992) Peripheral retinal changes and<br />

axial myopia. Retina 12: 12-17.<br />

Table 1 Summary of potential ocular fundus changes in high myopia<br />




Optic disc<br />

crescent<br />

Posterior pole<br />

Biomechanical<br />

Observed in most myopes,<br />

100% of eyes with axial length<br />

≥28.5mm 11<br />

None, unless o<strong>the</strong>r pathology<br />

also present<br />

----<br />

Posterior<br />

staphyloma<br />

Posterior pole<br />

Biomechanical<br />

Observed in 76% of myopes,<br />

-3 to -38D 16<br />

Can be progressive and result<br />

in vision loss<br />

Choroidal neovascular<br />

membranes<br />

Lacquer cracks<br />

Posterior pole<br />

Biomechanical<br />

Observed in 4% of high<br />

myopes >6D 19<br />

Guarded prognosis for vision<br />

Choroidal neovascular<br />

membranes<br />

Chorioretinal<br />

atrophy<br />

Posterior pole<br />

Degenerative<br />

Observed more commonly in<br />

younger high myopes, 23% of<br />

myopic eyes with axial length<br />

>24.5mm 11<br />

Guarded prognosis for vision<br />

if at <strong>the</strong> macula<br />

Associated with posterior<br />

staphylomas, lacquer cracks<br />

Fuchs’ spot<br />

Macula<br />

Neovascular<br />

Observed in 5-10% of eyes<br />

with axial length ≥26.5mm 11<br />

Guarded prognosis for vision<br />

Associated with posterior<br />

staphylomas, lacquer cracks<br />

Lattice<br />

degeneration<br />

Periphery<br />

Degenerative<br />

Observed in 13-30% of<br />

myopes 23,25<br />

None, unless secondary<br />

pathology occurs<br />

Retinal detachment<br />

Pigmentary<br />

degeneration<br />

Periphery<br />

Degenerative<br />

Observed in 17% of myopes 25<br />

None<br />

----<br />

Paving stone<br />

degeneration<br />

Periphery<br />

Degenerative<br />

Observed in 27% of myopes 25<br />

None<br />

----<br />

White without<br />

pressure<br />

Periphery<br />

Biomechanical<br />

Observed in 23% of myopes 25<br />

None, unless secondary<br />

pathology occurs<br />

Occasionally retinal tears<br />

Prevalence values should only be used as an indication of how common <strong>the</strong>se changes are in <strong>the</strong> myopic eye.<br />

Reported prevalence values vary greatly between studies, due to differences in <strong>the</strong> age of subjects and severity of <strong>the</strong> myopia.<br />

www.optometry.co.uk 35

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