Occlusion of the Arterioles

Blockage, as opposed to hardening and shrinking, of the blood vessels in the retina or the optic nerve causes much more abrupt signs of vision-loss. Depending upon which part of the system is affected, loss may be partial or it may be total. Recovery takes place over a period of months, and is likely only to be partial. If an artery is blocked, recovery is unlikely unless the blood can find an alternative route. (Arteries convey blood from the heart to the body, veins convey blood from the body back to the heart.) Such a condition is miserable to observe because even with early treatment a successful outcome is rare. Patients become easily despondent and sometimes seek fringe treatments which, while temporarily boosting morale, produce no long-term improvement. The blockage of a vessel in the eye is also generally a symptom or signal of a much deeper degeneracy in the blood circulation system, and a general physical check-up must always follow an eye diagnosis. Many otherwise seemingly healthy adults in their fifties suddenly suffer this form of loss of sight, and within a matter of days their mental attitude towards life is changed and they realize that their physical zenith is well and truly passed.

Blockage of the arterioles is perhaps the most common retinal problem among the normal- or average-sighted. Its incidence is low enough. However, there are other even rarer conditions, such as periphlebitis and blood dyscrasia. For the purposes of this account they can be passed over, but something should be said about sickle cell anaemia. This is an inherited abnormality of the haemoglobin molecule concerned with sulphur linkages. An estimated ten per cent of black people in the United States, and an estimated eight per cent of black people in Britain, are born with a sickle cell anaemia trait. That is to say, they are carriers of the disease. Between 20 and 25 per cent of these have the disease itself, which also affects a small minority of Mediterranean people. The haemoglobin makes the red blood cell an abnormal (sickle) shape and unable to function as an efficient carrier of oxygen. Those afflicted are likely to develop acute and even chronic retinal abnormalities for which, sadly, there is at the present time no cure. Money for medical research is administered very largely by white people in white foundations, and this provides one unpleasantly cogent explanation as to why so little has been done, until relatively recently, to overcome an ‘outsider’ disease.

Retinal Degeneration

Retinal failure is not invariably explicable in terms of blood deficiencies or defects. There are many other conditions, some of cause unknown. For want of a better name they are called degenerations. The suffix `-pathy’ is sometimes added, giving retinopathy. (Similarly some diseases of the cornea are called keratopathy.) Retinopathic conditions are generally progressive, developing over very long periods of time. Retinitis pigmentosa is one such condition, resulting in loss of visual field and eventual blindness. Night blindness may be the first symptom, although the practitioner, looking at the retina through an ophthalmoscope, easily recognizes the signs long before the patient realizes there is anything seriously wrong with his or her eyes. The doctor sees areas of pigment surrounding narrowing blood vessels. Retinitis pigmentosa can be either hereditary or acquired, and it is sometimes associated with other systematic abnormalities. Much is unknown about this disease, which can have tragic consequences even among the young, and so not surprisingly many different treatments are offered. In this and some other progressive diseases there are usually periods of apparent improvement, of temporary remission, generally governed by the patient’s mood. The promise of treatment and the build-up of expectations, especially if the treatment is to be undertaken abroad, lifts the patient’s spirits, and this alone is sometimes enough to affect the progress of the condition beneficially, regardless of any efficacy that the proposed treatment may have. The same kind of expectant aura, with the same kind of short-term relief, is also sometimes derived from acupuncture, hypnosis and other fringe medicines.

As far as retinitis pigmentosa is concerned, however, almost every known approach to aetiology and treatment has been attempted and eventually proved of no great value. Perhaps tomorrow there will be better news. Meanwhile the disease does exemplify another aspect of the medical world. The patients who have this condition, and more especially the parents of child sufferers, have combined to form a strong society with sufficient funds to establish research programmes and collect data from the society’s members. Patients and their relatives as a group are in effect saying to doctors: ‘We have the financial and social means, you produce the result.’