LIVING WITH RETINITIS PIGMENTOSA
Accepting Retinitis Pigmentosa
You may have been told recently or you have known for some years that you have Retinitis Pigmentosa (RP). This diagnosis could well help to explain the months or years of not being able to see properly in the dark, of stumbling into things and of falling over objects which you did not see. You will possibly have been told that, at present, there is no cure for RP and that you have to face the prospect of slowly deteriorating sight. Slow loss of sight is a difficult disability to live with, especially as you may not receive the immediate sympathy and understanding usually shown to the totally blind. Indeed many people will not believe that you have a loss of sight because you have no obvious sign of visual impairment.

The first and hardest step towards living positively with a disability is accepting it. If you have RP this means knowing the limitation of your vision and learning to use intelligently the visual clues you still receive. In certain circumstances a normally sighted person must also do this. For example, the driver who suddenly plunges into fog has two alternatives. He can panic and perhaps cause an accident or he can recognise his visual limitations, take note of what he can see and move cautiously down the road. Likewise those with RP can panic or they can adjust to their changed circumstances and move on down the road of life.

Accepting that you have RP will not be easy. You may go through periods of despair and of feeling resentful, bewildered or even angry. All these reactions are understandable, especially as the very nature of this disorder makes adjustment difficult but the way in which you deal with it determines the type of life you and your family will share from day to day. If you try to ignore it, you will suffer constant reminders that it is there. If you write yourself off as totally incapable, you will be missing out on many of life's enriching experiences. If you can tackle steadily and thoughtfully each new problem as it arises, using clues that come through your other senses as well, you will find that you can live a more positive and enjoyable life.

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Some Effects Of Retinitis Pigmentosa
RP can manifest itself in many ways since it is not one disorder but many with similar symptoms. For some, the loss of sight is slow and there may be only a small loss over perhaps ten years or more. Others have periods of rapid loss, often with years in between with no apparent decline. Some will have been aware of poor vision since childhood or teens; for instance, they probably experienced difficulty with ball games or getting about at dusk. Classically the outer fringes of vision are affected initially, causing apparent clumsiness and inability to see at dusk. In other cases the central vision may be affected first, causing difficulty in detailed work such as reading and in identifying colours.

With so many variations in the symptoms and effects, it is not surprising that the public find RP a difficult condition to understand. When many with RP can still see to read or gaze into the distance, to pick out landmarks or respond to a smile, it is hard to appreciate that they may have serious visual limitations. Yet it is so important for mutual understanding, especially within the family, that the normally sighted person should recognise and comprehend the difficulties of RP. For example, a person experiencing the early stages of RP may have almost perfect day vision but at night, in brilliant sunshine or in rapidly changing light conditions, the same person may react as if they are almost totally blind. Loss of part of the visual field is not always understood. As a person with normal sight stares ahead, they will see objects to either side, above and below the point on which their eyes are fixed. We often hear the expression "I saw it out of the corner of my eye". Many people with RP lose this facility.

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Help From Others
How can the family best help relatives with RP? Don't be over protective, but observe what he or she can do without help. Listen to any suggestions such as how to arrange the house, keeping the floor clear of objects, not moving the furniture around too often, shutting cupboard doors and never leaving doors half open. When out, try to give warning of unexpected hazards such as steps (and indicate whether they are up or down and how many). If you are the one with RP, explain how much you can do without assistance and where and when help would be appreciated. The family that is always tense and over protective can be morale destroying. When you are helping your family to understand your disability, use incidents that are particularly relevant. For example, when you have just tripped over your son's football boots in the hall, use that situation to make a point about putting things away but try not to let it turn into a nagging match. Living with a disability can be hard for the other members of the family too and the one who has it can do much towards making life happier by explaining to those around how they can best be helpful.

Remember that RP is a progressive disorder and that, consequently, the needs of a person with RP will change from time to time. It is often difficult for members of the family to understand that something which was helpful five years ago, may be of little use today.

Some people may feel too embarrassed to tell others about their sight problem and try to conceal the difficulties they are experiencing. If you can overcome these sorts of feelings and be open about having RP, then your life will become much easier and less stressful. On the other hand, try to avoid becoming the social bore who never stops talking about his problems. You have the choice: to grow into an RP person or a person who has RP.

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MEDICAL ASPECTS OF RETINITIS PIGMENTOSA
Structure Of The Eye
Retinitis Pigmentosa is the name given to a group of disorders of the Retina, all of which result in a progressive reduction in vision. The Retina is the light sensitive tissue inside the eye in which the first stages of seeing take place. For those not familiar with the structure of the eye, think of it as similar to a camera, which has a lens at the front, the purpose of which is to focus light onto a light sensitive film inside the camera towards the back. In a similar way, the eye is a hollow sphere, with a lens at the front which focuses light onto a light sensitive tissue, which lines the inside of the eye at the back. This tissue is called the Retina and it is the area affected by all types of RP. In RP disorders, various parts of the Retina cease to function.

Section Through An Eye


The Retina consists of two main layers, a thin one called the pigment epithelium and a thicker one, made up of many layers of cells, called the neural retina. The neural layer of the retina is responsible for responding to light, whilst the pigment epithelium looks after many of the biochemical needs required for this process, a sort of food supply.

The cells in the neural retina are arranged in layers and one of these is made up of photoreceptor (light responding) cells. These are on the back of the neural retina, the side furthest from the incoming light and immediately behind them is the pigment epithelium. Although this seems strange, it is an arrangement found in all animals with backbones. There are two types of photoreceptor cells, one called rods and the other called cones. The cone cells are concentrated near the centre of the Retina and are responsible for seeing colour and detail in good light conditions. The other group, the rod cells are found towards the edges of the Retina and are used in poor light or to see items to the side of our line of vision. For example, you will be using your cone cells to read this but your rod cells will give warning of a stool in the middle of the floor or an overtaking car when you are driving. The rod cells will also be used when walking down an unlit road at dusk. We have far more rod cells than cones. The Retina of a human eye will contain about 120 million rod cells but only 6 million cone cells.

On the opposite side of the Retina is another layer of cells called ganglion cells. These are like message carrying 'wires' which join to form the optic nerve, the 'cable' which joins the eye to the brain. The light sensitive cells (rods and cones) generate tiny electrical impulses when light fails upon them and these impulses are passed, via a layer of intermediate neurones, to the ganglion cells. From here the impulses pass through the long ganglion cell fibres, which ultimately become the optic nerve, carrying the electrical impulses to the brain. This is where the picture is assembled, the process we call seeing.

Retinitis Pigmentosa is a group of hereditary disorders whose common feature is a gradual deterioration of the light sensitive cells of the Retina. The name Retinitis Pigmentosa was applied by a Doctor Donders in 1857. It is not a good name and in more recent times the condition would probably have been named "Retinal Dystrophies" but the old name is well known throughout the world, so it stays.

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Visible Signs Of Retinitis Pigmentosa
The inside of a normal eyeball is examined by a doctor looking through the front, using an ophthalmoscope. The view that the doctor sees is called the fundus. It has an orange red appearance due to the presence of pigment containing cells, the pigment epithelium, which protects the rods and cones and provides them with essential nutrients. The main features visible on the fundus are the retinal blood vessels, which spread out from a pale, whitish disc, the head of the optic nerve and in the centre a somewhat denser area called the macular.

When the fundus of someone with RP is examined, the orange red area is broken by black or dark brown star shaped concentrations of pigmentation, hence the Pigmentosa part of the name applied by Dr Donders. Examination of eyes donated by RP sufferers at death, has shown that this pigmentation is caused by cells from the pigment epithelium budding off and settling within the layers of the neural retina. In the late stages of RP a thinning of the retinal blood vessels is seen, probably resulting from the loss of many retinal cells reducing the need for blood.

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Symptoms Of Retinitis Pigmentosa
The symptoms of this group of disorders usually become apparent between the ages of 10 and 30, although some changes may become apparent in childhood. In one type of RP, Leber's Amaurosis, children may become blind or almost so, within the first six months of life. By contrast, some types of RP may only show symptoms late in life. In the more common types of RP, a person will have a history of visual problems at dusk or in poor light, so-called night blindness and a gradual reduction in the field of vision, loss of the outer edges, resulting in a tendency to trip over things. In some cases RP is first diagnosed following a road accident.

The first reaction amongst many people is to go for an eye test believing that they need glasses. Although glasses do a marvellous job correcting problems with the eye's lens, they cannot help a deteriorating Retina. As the outer fringes of the field of vision gradually disappear, the RP sufferer is left with the condition commonly referred to as tunnel vision. Many people retain this tunnel of useful vision until quite late in life. The speed of loss of vision varies considerably from person to person, due to the many forms of RP.

In one category of RP, the loss of vision begins in the central area. This is referred to as macular dystrophy (because the central macular area is affected). It causes an inability to read or carry out other work involving detail, although the person may have few mobility problems for several years.

There are many syndromes associated with RP, which result in multiple loss, such as Usher syndrome, in which sight and hearing are both affected and information on these can be supplied on application to the BRPS Office.

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Inheritance Patterns
Retinitis Pigmentosa can be classified according to its inheritance pattern. The different forms of RP result from the presence of one or two abnormal Genes. There are three possible inheritance patterns, Autosomal Dominant, Autosomal Recessive and X-Linked and these are described in detail in the BRPS booklet 'Genetics and RP', available from the BRPS Office.