Childhood Retinal Dystrophies

The retina is a light sensitive tissue layer lining the inner back surface of the eye. The function of the retina is to change light signals coming into the eye into an image in the form of electrical signals. These signals then travel to the visual part of the brain via the optic nerve for further interpretation.

Retinal dystrophy is a general term that encompasses a wide range of retinal diseases that have similar visual symptoms and appearances on examination of the back of the eye. Retinal dystrophies may occur spontaneously but more frequently, are inherited. The effects of retinal dystrophies on vision are dependent on the site and extent of damage to the retina. Examples of some of the more common retinal dystrophies are:

1. Retinitis Pigmentosa (RP)

   Retinitis pigmentosa is the term for a wide range of inherited retinal diseases that cause a gradual reduction in vision. It occurs in 1 in 3000 people. Typically, the child initially starts complaining of problems with night or peripheral (side) vision around the age of ten years. The age of onset is variable according to the type of RP the child has. RP tends to progress slowly over a course of years and eventually colour and central vision may be affected. It is very uncommon to completely lose all vision in RP. Usher Syndrome is a common form of RP where the patient also has hearing loss.

2. Stargardt Disease (Juvenile Macular Dystrophy)

   The macula is the part of the retina, which is responsible for central vision. Stargardt disease can occur as early as the age of six years old and the initial visual complaint is reduced central vision in both eyes and problems with colour vision. The visual prognosis of Stargardt's Disease is poor and early visual rehabilitation is of strong importance to allow the children to maintain independence.

3. Leber's Congenital Amaurosis (LCA)

   Leber's Congential Amaurosis is a rare retinal dystrophy that usually appears at birth or in the first few months of life. It affects 1 in 80,000 children. Children with LCA have poor vision and nystagmus (involuntary wandering eye movements). Some children show preference for bright lights whilst other prefer dark environments. It is a genetic disease caused by a mutation in the coding system for one of the important eye genes. Due to it's early occurrence in children, the diagnosis of Leber's is confirmed with electrical testing.