Retina Degeneration Surgery

Retinal degeneration is a range of eye disorders that are very difficult to describe as each case is so different. If you suspect that you have retinal degenerations or any other eye problem, it is best to consult with an ophthalmologist who specialises in the care of the eye. The nature and progress of the condition and the possible need for retinal surgery can be only determined by knowing the full details of the patient’s examination and family history.

Retinitis Pigmentosa

Retinitis Pigmentosa (RP) is a group of hereditary diseases of the retina. The retina (at the back of the eye) acts like a film in a camera, receiving and processing everything you see. The retina is a delicate layer of cells which pick up pictures and transmit them to the brain. In humans there are two types of light sensitive cells in the retina: rod cells and cone cells.

Rod cells pick up movement out of the corner of the eye, and in a normal eye it is the rods that operate in poor light or at night. There are about 120 million rods in each eye and they are more numerous towards the outer edge of the retina. The cone cells are used in colour vision and in close precision work, such as reading. There are not as many cones and they are more concentrated in the centre of the retina (the macula).

RD may be caused by a breakdown in the function of the rods or the cones in some part of the retina. The retina is so complex that breakdowns may occur in a variety of ways, and so RD is not a single disorder but a great number of disorders. The breakdown of cone function is often called Macular Degeneration. There are other disorders similar to RP such as Gyrate Atrophy, Choroideremia and so on. The common feature is retinal degeneration. Researchers are trying to find specific causes of retinal disorders.

The symptoms of RP depend on the type of RP. One early symptom of RP is difficulty seeing at night or in poor illumination. With loss of rod function there is a narrowing of the field of vision and as the degeneration gradually progresses it seems as if you are looking down a tunnel. This is why RP is sometimes referred to as “tunnel vision”. Other symptoms include slow light-to-dark adaptation times and poor contrast sensitivity. This inability to differentiate weak contrast affects children in the classroom – writing on the blackboard and on the overhead projector is difficult to read. This also accounts for difficulties in negotiating concrete or carpeted stairs without edge markings.

Macular Degeneration

There are two groups of macular degeneration, those that affect the young and those that affect the old. Age related macular degeneration (AMD) usually affects people over the age of 50 and there are two distinct types: “wet” AMD and “dry” AMD. “Wet” AMD results from the growth of abnormal new blood vessels in the choroids, causing an accumulation of fluid in the macula, which leads to retinal damage. This type of degeneration is often treated with laser surgery or photodynamic therapy (PDT).

"Dry" AMD represents at least 80% of all AMD cases and results in atrophy of the retina. Usually yellowish-white round spot called drusen first appear in a scattered pattern deep in the macular area. Later degeneration of both the pigment epithelium and the cones begins.

While AMD is not inherited in a predictable way, heredity may be involved to some extent. Juvenile inherited macular degeneration occurs much less frequently. One type of this disorder is Best disease (Vitelliform dystrophy), an autosomal dominant disorder that is usually diagnosed at quite a young age. Another is Stargardt dystrophy, which is an autosomal recessive condition that causes atrophy in the macula. All of these conditions affect the central vision often causing blurring of vision, distortion of lines and shapes, blind spots and an increasing difficulty in reading and recognizing faces. Side or peripheral vision is usually not affected and so mobility is not affected either.

Usher Syndrome

Usher Syndrome is RP accompanied by hearing loss. The hearing loss is congenital, stable and usually quite severe, although severity can vary in different individuals. Hearing can usually be assisted by modern electronic aids. Usher Syndrome is a recessively inherited condition. One of the greatest difficulties experienced by sufferers is increased isolation, as the restrictions on both spoken and visual communication increases.

Is Retinal Degeneration Inherited?

In most cases, the answer is yes. The most common form of inheritance is called recessive. In this type both parents carry the genes which causes RP. They themselves are unaffected but there is a 25% chance that their children will have RP. Another form of RP inheritance is X-linked. In X-linked RP, females carry the gene causing RP. When a female carrier marries an unaffected male, then there is a 50% chance that their sons will be affected, and a 50% chance that their daughters will be carriers. X-linked RP is one form for which carriers can often be detected. In X-linked RP when an affected male marries a non-carrier female, their sons will not be affected, but all their daughters will be carriers. There is also a dominant form of RP which can strike in every generation of a family. Since RP runs in families, all members in an affected family are urged to have a thorough eye examination. When planning a family, expert genetic counselling should be sought.

Does Retinal Degeneration lead to blindness?

To the layman, blindness is complete loss of vision. Some people with retinal degeneration may become blind; however, most retain limited residual vision though they may be termed “blind” for legal purposes.

How quickly does sight diminish?

The rate of sight loss for each person is different and can be assessed by an eye specialist. If the disorder runs in a family, the pattern may be similar within that family. There is usually a gradual degeneration so that in most cases there is time to adjust to the visual handicap.

Does Night Blindness mean RP?

Night blindness alone does not necessarily represent a progressive eye disorder. However, anyone suffering from this should be tested for retinal degeneration as a precaution.

Is there any treatment to arrest the progress of retinal degeneration?

The causes of retinal degeneration are numerous, so it is unlikely that a single treatment will emerge to slow down the progress of all forms of retinal breakdown. For people with Usher Syndrome and RP a daily dose of 15000 international units of Vitamin A Palmitate (only) has been shown to slow the degeneration of the cone ERG. A blood test must be taken to ascertain liver function and Vitamin A levels in the blood BEFORE taking this treatment. Pregnant woman must not take high doses of Vitamin A under any circumstances and this treatment must be undertaken in consultation with your doctor or eye specialist. With children under the age of 18 doctors should be consulted on the advisability and dosage.

Can retinal degeneration be easily diagnosed?

This depends on the type and extent of the degeneration. A characteristic change in the appearance of the retina may be visible to the ophthalmologist. A proper eye examination is needed to determine the precise state of the retina. A visit to a Retinal Clinic is advised. Here the field of vision will be ascertained, the central vision measured (visual acuity) and an electro-retinogram (ERG) test performed. This test measures the electrical activity of the retina and how it changes with light. Specific graphs in this test help clinicians to accurately diagnose the type of degeneration. This, coupled with a careful analysis of the family history, will help classify the type of RP and determine whether retina surgery is required.

Low vision aids

Low vision devices are designed to enable people suffering from retinal degeneration make the most of the eyesight they have. Each person is different with diverse needs. Lenses, magnifiers, closed circuit television readers or other sophisticated electronic gadgets may help. Specific low vision assessment is necessary to establish which kind of aid or retinal surgery will be best suited for the individual’s needs.