High myopia
 

The optic disc has irregular peripapillary atrophic crescent (this is due  to failure of the retinal pigment epithelium and choroid to reach the disc  margin). There are thin white lines (termed lacquer crack caused by breaks  in Bruch's membrane) extending from the optic disc. Other signs to look for: Foster-Fuch's spot (which is RPE hyperplasia following subretinal   neovascularization and haemorrhage) subretinal haemorrhage suggesting subretinal neovascularization  presence of staphyloma is suggested by dipping of the vessels into   the cavity look for any evidence of previous retinal detachment operation   (peripheral chorioretinal scars or indentation)

Questions:

1. What is the definition of high myopia?

Answer
Myopia greater than -6.00D

2. What are the causes of myopia?

Answer
Axial - the most common cause in which the length of the eye is increased. This may be simple or pathological in which the myopia exceeds -6.00D
Curvature -  due to the increased curvature of the cornea
Index - due to the increased refractive index of the lens as seen in nuclear sclerosis

3. Why are patients with high myopia at risk of retinal detachment?

Answer
The peripheral retina in high myopia is thin and therefore predisposes the patient to retinal hole and tear. In addition, the incidence of  lattice degeneration and posterior vitreous detachment are increased.

Return to the main page