Nightlight Helps Prevent Blindness in Diabetics

People suffering from adult onset (type 2) diabetes may be able to prevent damage to the retina and possibly blindness by leaving a nightlight on in their bedroom while sleeping, according to a study in Lancet (2002;359:2251–3).

Deterioration of the retina, or retinopathy, is a common consequence of diabetes and may affect as many as half of all diabetics. Unfortunately, there are few warning signs of this condition and most diabetics do not develop any symptoms until vision is partially lost or complete blindness occurs. Conventional surgical treatment may be helpful if retinopathy is caught early, but has a poor success rate when the disease is severe. There is no known cure for diabetic retinopathy.

For reasons not completely understood, darkness seems to increase the requirement for oxygen in the retina. Healthy individuals are able to meet this increased requirement during periods of darkness, but diabetics, who have impaired capillary function, may be unable to deliver the additional oxygen the retina needs at night. Scientists have speculated that a deficiency of oxygen results in damage to the retina. This theory is supported by research showing that color and contrast vision improved in diabetics given oxygen therapy. If this theory is correct, then keeping a light on at night might prevent retinal oxygen depletion, thereby slowing the development of retinopathy.

Researchers studied the effects of darkness on the retinas of seven diabetic and eight healthy adults of similar age. Measurements of retinal function were taken periodically during 20 minutes of darkness. Additional measurements were taken before and after oxygen had been administered in darkness. Compared with non-diabetics, those with type 2 diabetes had significantly lower retinal function during darkness, suggesting inadequate oxygen flow to the retina. When oxygen was administered to the diabetics, retinal function improved to the level seen in healthy volunteers.

This study provides circumstantial evidence that using a nightlight would be beneficial for diabetics. However, the study did not actually measure the effects of nighttime illumination.

Certain nutritional supplements may also be useful for preventing or treating diabetic retinopathy. One study showed that 150 mg per day of proanthocyanidins (a group of compounds found in pine bark, grape seed, and other plant sources) slowed the progression of retinopathy in diabetics. Other studies suggest 600 mg per day of bilberry (Vaccinium myrtillus) or 320 mg per day of ginkgo (Ginkgo biloba) may also help improve vision in people with mild to moderate diabetic retinopathy. More long-term studies are needed to corroborate these results.

Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of The Natural Pharmacist: Lowering Cholesterol (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice at New England Family Health Associates located in Southport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.

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