Light Therapy and Eye Safety

Can Bright Light Therapy Damage the Eye?

Researchers have expressed concern regarding the use of bright light therapy because the visible blue light wavelengths emitted by bright light therapy lamps may cause retinal damage and could contribute to the development of age related blindness. Refs. For many years cautions have been expressed that users of bright light therapy lamps be screened by ophthalmologists, and those with pre-existing retinal conditions or other risk factors abstain from light therapy treatment or be closely monitored. Refs. The risk of retinal damage to those using blue light or " blue-enhanced" light therapy units is even greater.

Blue visible light with wavelengths shorter than 480 nm induce greater oxidative stress in the outer retina than other visible light wavelengths. Indigestible debris that increases the level of oxidative stress when it absorbs blue light accumulates in the retina over a lifetime and is related to the development of age-related blindness. By age 75, more than one in every three people has their vision affected by Age-related Macular Degeneration (AMD), and this increases to over one half of people by age 85.

The combination of low intensity and the elimination of the more hazardous light wavelengths found in the blue portion of the visible light spectrum, as occurs with the patented light therapy technology of Lo-LIGHT therapy lamps, eliminates the risk of permanent retinal damage inherent in the use of bright light therapy lamps or blue light therapy lamps. Lo-LIGHT therapy lamps operate at normal indoor light intensity, and screen out the blue wavelengths of visible light that are most damaging to the retina.

People using Bright Light or Blue Light therapy while taking photosensitizing medications have an increased risk of eye damage. These medications, which sensitize the eye to damage by visible light, include nonsteroidal anti-inflammatory drugs (NSAIDs), most antidepressants, some antibiotics, diuretics, beta-blockers and other heart medications. Guidelines have been established recommending that Bright Light therapy not be used with these photosensitizing medications. In contrast, Lo-LIGHT therapy lamps are less hazardous than normal indoor lighting. Refs.

A case report in the American Journal of Psychiatry described a person who combined the use of Bright Light therapy and an antidepressant medication. After five days of using light therapy this patient suffered a "marked reduction in visual acuity contrast sensitivity." Retinal examination found lesions in the retinas of both eyes. Ref.

In addition to those taking photosensitizing medications, those with an increased risk of vision loss from bright or blue light therapy include people with a pre-existing ocular condition or a susceptibility for retinal damage such as those with diabetes and people over 40. The age related increase in susceptibility to blue light-induced damage in retinal tissue results from an age-related decline in the ability of retinal defense mechanisms to repair oxidative damage after age 40, as well as the accumulation of phototoxic debris that occurs in retinal tissue over a lfetime. Refs.

It is worth considering what Herbert Kern, the first person to use bright light therapy and therefore the person with the longest history of bright light therapy use, said in the Sept 14, 2007 issue of Science regarding his developing AMD. After explaining that light therapy became less and less effective for him over the years as his eyesight faded, he said "Now I can hardly see, and all hell has broken loose" "I have had periods of depression lasting over a year, and highs lasting as long."
See Part II - Light exposure and AMD
More information on the loss of vision from the use of bright light and blue light therapy.

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