There are no absolute contraindications to light therapy, although there are some circumstances in which caution is required. These include when the patient 1) has a condition that might render his or her eyes more vulnerable to phototoxicity, 2) has a tendency toward mania, 3) has a photosensitive skin condition, or 4) is taking a photosensitizing medication or herb (such as St. John’s wort or a psoralen).
Although there have been no documented cases in which light therapy, when properly administered and supervised, has caused damage to the eyes, the potential for such damage has been raised as a theoretical possibility (M. Terman et al. 1990). The likelihood of light-induced damage to the retina might be increased in patients with retinal diseases such as macular degeneration or retinitis pigmentosa. Patients with retinal abnormalities should not be given light therapy without careful prior evaluation and ongoing supervision by an ophthalmologist. The degree to which patients with normal eyes should have their eyes regularly monitored during the course of light therapy has been debated, with some advocating more stringent monitoring and others advocating less stringent monitoring (Waxler et al. 1992). Concomitant use of certain antidepressants or other medications that may enhance phototoxicity has been cited by some investigators as a reason for additional caution and more frequent monitoring (M. Terman et al. 1990), although no increased prevalence of eye damage has been reported in persons on these medications, despite regular exposure to bright sunlight. In addition, there is no evidence of any increased prevalence of eye problems in patients who have been receiving light therapy for several years, a proportion of whom have been taking concomitant medications (Schwartz et al. 1996).