Retinal pigment degeneration Topic 44
=there are a wide variety of dystrophies °enerations of the retina
A common one is called Retinitis pigmentosa
- A heredity disorder mainly affecting the rods over the coins
- 3 forms Autosomal recessive (most common) ,autosomal dominant and X-linked recessive is the least common
- 5/1000 of world inhabitants suffer from it
- Appears during childhood and progresses slowly but often resulting in blindness in advanced middle age
- It is usually bilateral and eyes are affected the same
- Clinically , night blindness due to reduction in rods and may be a very important sign
- Tubular vision occurs in advanced cases
- Signs
- a) Usually around vessels pigmentary changes can be seen and they resemble osteocytes Usually they start in the equator then spread from there
- b) Attenuation of retinal arterioles and thread like appearance
- c) Optic disc becomes pale and waxy due to optic atrophy
- d) Cystoid macular oedema could be present
- e) Visual field may be affected showing annular or ring-shaped scotomas around the equator region which then spreads
- Associations :
- 1. Ocular =myopia, primary open angle & Subcapsular cataract s
- 2. Systemic= Laurence-Moon-biedl syndrome→pigmentosa+ obesity ,polydactyl, hypogenitalism+ mental deficiency Usher syndrome = pigmentosa + deafness
Other atypical versions
Sectorial retinitis pigmentosa= affect only one sector of the retina Pericentric retinitis pigmentosa= only around macula
Treatment
- No effective treatment
- Reduction in progression (vitamin A+E), vasodilators ;Low vision aids ;Prophylaxis by genetic counselling
Peripheral retinal degeneration (degeneration in periphery) Associated with retinal detachment .6-10& of pop, 15-20 of myopic