AIMS--The study was designed to measure the prevalence, range, and severity of eye involvement in leprosy patients; to relate this to disease type, duration, and treatment to identify risk factors; and to provide practical guidelines for programme managers and field staff on the prevention of blindness. METHODS--The visual outcome was assessed in a population based sample of patients in Kasese District, Uganda followed for up to two decades, and related to disease features and treatment. A total of 678 patients responded to an invitation out of 2715 registered since 1973. RESULTS--Low vision was present in 4.4% of people and blindness in 1.3%, with 1.5% and 0.6% respectively being due to leprosy. Some 12.4% of patients had iritis, of whom 33% had visual loss in one or both eyes, 3.7% of patients had lagophthalmos, and 11.7% had lens opacity. For multi-bacillary (PB) cases, the adjusted odds ratios were: for iritis 4.6 (95% CI 2.6-8.2), for lagophthalmos 1.4 (0.6-3.2), and for lens opacity 1.7 (1.0-3.0). Potentially sight threatening (PST) lesions were present in 16.8% of patients (95% CI 14.0-19.6). CONCLUSION--Levels of eye involvement in this study are low compared with many surveys. Visual loss is uncommon and is more often caused by other diseases; in the present era of multidrug therapy (MDT) it is very unlikely to be caused by leprosy. It is more common with advancing age. PST lesions, especially iritis, may occur in both PB and MB cases, even if the diagnosis of leprosy is made early and MDT started immediately; they may occur also after completion of MDT. But eye complications need not proceed to loss of sight if treated promptly, and blindness can be avoided. Training of front line staff is therefore crucial.