Medical Retina & the Posterior Segment:
Case 20

This 75 year-old man presented to the eye casualty with a one week history of distorted left vision. His visual acuity was 6/12 in the left eye with the above posterior segment appearance. He had no history of hypertension or diabetes mellitus.

a. What is the most likely diagnosis?

Age-related macular degeneration with subretinal neovascular membrane.
The above picture shows circinate exudate in the macula with a greyish lesion in the centre representing the choroidal neovascular membrane with or without pigment epithelial detachment.

b. What other condition may be responsible for the above appearance?

Circinate exudate in the macula can be caused by two mechanisms:
  • Breakdown of the inner blood retinal barrier (tight junctions between the retinal vascular endothelial cells). For example: diabetes mellitus, retinal vein occlusion, chronic uveitis and radiation retinopathy.
  • Breakdown of the outer blood retinal barrier (tight junctions between the adjacent retinal pigment epithelial cells). For example: choroidal neovascular membrane due to macular degeneration, choroidal rupture, choroidal melanoma and presumed histoplasmosis syndrome.

c. How would you manage this condition?

The patient should be assessed for her suitability for laser treatment (which is the only statistically proven effective treatment).

Fluorescein angiography should be requested to look for the type and location of the subretinal neovascular membrane. Patient who will benefit from laser will be those with classical choroidal neovascularization which is located outside the fovea. Those with occult choroidal neovascular membrane (in which the membrane is diffuse and poorly defined) or subfoveal lesion are not suitable for laser.

In centre where indocyanine green (ICG) videoangiography is available, those with occult choroidal neovascular membrane as seen on FFA should undergo ICG. ICG gives a better visualization through the pigment and blood and may localize area of choroidal neovascularization for laser therapy.

The visual prognosis is usually poor even in those who can be treated with laser as the choroidal neovascularization has a high recurrence rate (about 50% within 3 years)

Click here for the questions Click here for the main page Click here for MRCOphth / MRCS tutorials