Thyroid dysfunction and affective illness.

is a prerequisite for setting priorities.Without such data it may be impossible to persuade governments, whose attention may be diverted by other demands, to direct limited resources to blindness.In some poor countries trained ophthalmologists cannot be integrated into the national health service because of lack of money-both India and Senegal have ophthalmologists working as taxi drivers and waiters.Perhaps the greatest advance in tropical ophthalmology was the introduction of ivermectin (donated by Merck Sharpe and Dohme) to treat onchocerciasis.One dose of ivermectin a year reduces transmission by three quarters.As it kills only microfilaria, however, it must be taken for at least 10-15 years, which is the lifespan of the adult female in the human body.Research is currently focusing on the logistics of the massive distribution programme required.The tragedy of childhood blindness may be easily over- looked.Vitamin A deficiency accounts for 70% of cases, and as this is related to concomitant measles and malnutrition more than halfofthose affected die within a year.Distributing high dose vitamin A capsules (donated by Hoffmann-La Roche, Switzerland, under its task force "Sight and Life") is part of the solution.(So is improved sanitation, female literacy, vaccination against childhood diseases, improved diet, education, and eliminating poverty.)Another disease linked to ignorance and poverty is trac- homa, a leading cause of blindness in several African countries.The single most effective means of control is regular face washing.Providing clean water to all communities and use of tetracycline eye ointment by those who are infected might eradicate this scourge.With national wealth dwindling in developing countries the extensive skill and experience of international agencies working to prevent blindness makes them valuable allies.Among the larger agencies, Christoffel Blindenmission works through mission hospitals, the Royal Commonwealth Society for the Blind (Sight Savers) prefers to work through host governments, Helen Keller International has particular skills in technical cooperation and planning the distribution of vitamin A, and the International Eye Foundation emphasises primary eye care.Each year they have millions of dollars to spend.