Ophthalmologic examination of patients with seasonal affective disorder, before and after bright light therapy

We assessed the potential ocular hazards of bright light therapy for patients with seasonal affective disorder, after both short- and long-term treatment, and identified prospective patients with pre-existing ocular abnormalities.

Fifty patients with seasonal affective disorder received daily exposure to artificial light in the morning or evening for 30 minutes at an illuminance level of 10,000 lux (irradiant dose, 0.016 J/cm2). Ophthalmologic examinations were performed before and after short-term treatment (two to eight weeks) and after three to six years of use during the fall and winter months. Over the four years of patient intake, the eye examination included subsets of the following tests: visual acuity, intraocular pressure, slit-lamp biomicroscopy, direct and indirect ophthalmoscopy, color vision, visual field, fundus photography, Amsler grid, ocular motility, pupillary reactions, contrast sensitivity, stereopsis, and the macular stress test.

No ocular changes were detected after short-term treatment. Long-term treatment (three to six years) of 17 patients, with cumulative exposure durations of 60 to 1,250 hours, also resulted in no ocular abnormalities.

Light therapy yields about 75% clinical remissions. It is effective as an antidepressant and appears safe for the eyes. Current knowledge is insufficient to specify any definite ocular contraindications for bright light therapy, although we recommend that patients with preexisting ocular abnormalities and those using photosensitizing drugs undergo treatment only with periodic ophthalmologic examination.