Ocular Manifestations of Nutritional Disease

MALNUTRITION as a cause of blindness has been and still is, much underestimated. In many countries it is the chief cause of blindness in young children. The onset is insidious and difficult to diagnose and the later stages proceed rapidly to irreversible damage. Opthalmologists have tended not to be particularly interested in conditions that do not make demands on their diagnostic or surgical skill and nutritionists have fought shy of such a specialized organ as the eye. It is however, of great importance that doctors trained in Europe and North America and going to work abroad should be prepared to deal with the medical problems as they exist there. They will find malnutrition rife in all its forms with eye involvement meriting their close attention. Furthermore, in all spheres of medical practice, it should be realised that on occasion malnutrition may be the cause of visual symptoms as for example in states of malabsorption, chronic alcoholism and when vitamins are inadvertently omitted from anti-allergenic infant formulae. The association of visual impairment and poor diet has long been recognised. Accounts of prolonged sieges, sea voyages, religious fasts and severe seasonal shortage of food and famines record the frequent occurrence of outbreaks of night blindness under these conditions. Among the earliest of all medical writings such as the Ebers papyrus (circa 1600 B.C.) and Chinese treatises of a similar period are to be found the well-known prescriptions of liver for night blindness and other eye diseases. The approach in these times, however, appears to have been a purely empirical one as the part played by poor diet was not known. It was not until the 19th century that xerophthalmia began to emerge as a clinical entity with its characteristic pathology, symptomatology and aetiological relationship to dietary deficiency. In the first quarter of the 20th century reports of the frequent occurrence of xerophthalmia and keratomalacia in Japan, Indonesia, India and elsewhere showed it to be a serious problem in many parts of the world. The discovery of fat-soluble vitamin A and the demonstration of its efficacy in the Danish outbreak during the first world war as well as in induced deficiency in experimental animals proved that the early retinal dysfunction and later corneal damage were both caused by vitamin A deficiency. In all probability another nutritional condition affecting the eyes lies inseparable from vitamin A deficiency among the early accounts. Nutritional amblyopia or retrobulbar neuropathy, resulting from deficiency of vitamins of the B complex, now appears to form a feature of some early accounts of pellagra and beriberi and reached epidemic proportions in some Far Eastern prisoner-of-war camps during World War II. Both these nutritional diseases causing blindness are serious problems in many parts of the world at the present time. They will be considered in more detail now, together with the role of malnutrition in certain other eye diseases. Detailed treatment of the historical aspects of this subject may be found elsewhere (Oomen, 1961, McLaren, 1963).