A reader asks:

 My husband has been diagnosed with SAD. His doctor told us it is okay to purchase a light box for therapy. He has some retinal problems. Any suggestions as to what we should look for or avoid?


It depends on the particular retinal pathology. You should not proceed without consultation with (and concurrence of) your ophthalmologist, and you should engage him/her for periodic monitoring. It would be a good idea to make sure there is a fundus photograph in the chart before beginning treatment. All that said, however, there are no specific retinal counter-indications for light therapy.

Lighting System Options

Some retinal problems make the eyes particularly sensitive to visual glare, so it is especially important to select a lighting system with a smooth diffusion filter. Light bulbs should be of relatively low color temperature (in the range of 3300 to 4500 degrees K) in order to de-emphasize high-energy blue irradiation, which can exacerbate glare. Maximum ultraviolet filtration is also very important. A system we have evaluated successfully in clinical trials, and which meets these standards, is described here, along with relevant articles, such as Light Therapy for Beginners: Six Steps. These articles have links to criteria for comparison shopping for light therapy apparatuses, and an online questionnaire to help you figure out what time of day would be best for you to begin treatment.