Forster-Fuchs' Retinal Spot

Synonyms: Fuchs' retinal spot, disciform degeneration in myopia, and choroidal neovascularization in myopia.

Forster described subretinal neovascularisation in severely myopic eyes in 1862 and Fuchs described a pigmented lesion at or near the fovea in 1901. They are both part of the same process.

Up to one third of severely myopic eyes can be affected.¹ It can strike at any age but it is a very significant cause of blindness in young people in developed countries. A study in Australia found the spots in 3 of 3654 elderly people, giving a prevalence of 0.1% in this age group.²

This is a condition seen in high myopia.

Symptoms

• Presentation is with deteriorating vision.
• There may also be complaints of visual distortion with wavy lines or an object that is being viewed has part missing.

Signs

• Ability to read the Snellen chart may deteriorate by 2 lines or more in a fairly short space of time.
• The Forster-Fuchs spot may be seen near the fovea but there are wide variations in the appearance.

• Histoplasmosis of the eye.
• Diabetic retinopathy
• Angioid streaks

Fluorescein angiography shows subretinal neovascularization from the choroid as the basic underlying disease in most cases.³

Drugs

There is currently no pharmacological treatment.

Surgical

Conventional treatments of laser photocoagulation or surgical extraction of the area of neovascularisation have had limited effectiveness. Newly developed treatments such as foveal translocation or photodynamic therapy have had favourable results in the short-term.⁴ More RCTs are needed.

Surgical excision of subfoveal choroidal neovascular membranes in high myopia in a study brought improvement of visual acuity of at least 2 lines in 45% and no change in 37%.⁵ Presumably there was deterioration in 18%. Another trial had similar results⁶ with the visual acuity improved by 2 or more Snellen lines in 39%, decreased in 35% and remained unchanged in 26%.

Without treatment atrophy occurs around the area and prognosis is very poor.⁴ The new vessels cause traction on the retina.
N.B. Phototherapy should not be used near the fovea as this is an avascular area.

A study from Moorfields in 1983⁷ showed a generally poor prognosis without intervention with 43% of the patients losing 2 or more lines of vision, while 60% were less than or equal to 6/60 at last follow-up. There was a direct relationship between visual acuity and the distance of the neovascular tissue from the fovea, and an inverse relationship between acuity and the size of the lesion. There seems to be a short neovascular growth phase, with early visual loss.

Older patients tend to have a poorer outcome than younger ones.⁸

Optical coherence tomography¹ can detect this at its early stages so that intervention may take place.