Role of iris changes as a cause of blindness in lepromatous leprosy.

Clinical and pathological investigations in a group of 113 patients with leprosy of long duration demonstrated the importance of iris changes as a cause of blindness. In lepromatous leprosy the so called "chronic iritis" produces iris atrophy with small nonreacting pupils which exaggerate the visual impairment created by developing lens changes and corneal opacities. The cause of this "chronic iritis" is believed to be neuroparalytic from early involvement of the small nerves of the iris, particularly the autonomic supply. Clinical and pharmacological evidence for this theory is supported by the histological changes observed in 18 specimens of iris removed during the course of cataract surgery, with progressive atrophy of the iris preferentially affecting the dilator muscle and leading to a nonreacting miosed pupil. Further pharmacological and histological studies are to be undertaken on lepromatous patients with iris involvement with a view to establishing possible methods of prevention.