DIGITALIS-INDUCED VISUAL DISTURBANCES WITH THERAPEUTIC SERUM DIGITALIS CONCENTRATIONS

Objective: To assess the role of digitalis in the development of visua l symptoms severe enough to warrant ophthalmologic consultation in pat ients who received digitalis and who had no other clinical or laborato ry evidence of digitalis toxicity. Design: Clinical case study. Settin g: Neuro-ophthalmology referral practice. Patients: Six elderly patien ts (aged 66 to 85 years) who received digitalis were referred to ophth almologists for evaluation of photopsia (five patients) or decreased v isual acuity (one patient). No patient had chromatopsia or nonvisual c linical manifestations of digitalis intoxication at the time of examin ation. Measurements: All patients had serum digitalis concentrations w ithin or below the therapeutic range. In most patients, the electroret inographic cone b-wave implicit time was longer than normal. Results: Discontinuation of digitalis therapy, which was possible in five patie nts, was followed by resolution of visual symptoms and by shortening o f the b-wave implicit time. Characteristic features of digitalis-induc ed photopsia were its dependence on illumination and its tendency to b e localized in peripheral visual fields. Conclusions: In an elderly pa tient receiving digitalis, the development of photopsia characterized by innumerable points of light in the peripheral visual fields or a de crease in visual acuity raises the possibility that the patient's visu al disturbance may have been digitalis induced. Digitalis-induced visu al disturbances other than chromatopsia or disturbances of color visio n may occur in elderly patients who have no other clinical manifestati ons of digitalis intoxication and who have a serum digitalis concentra tion within or below the therapeutic range.