The Darker the Better

The lifeguard who can't be bothered with sunglasses may look handsomer than his begoggled colleagues, but he is not the man to take the wheel during a moonlight drive. And the factory worker who tries to relax while squinting tearfully into the ocean glare may, as a result, have an accident at the work bench more than a week later. The effects of overexposure to bright sunlight last longer than most people realize.*

Dr. Robert H. Peckham, of Philadelphia's Temple University, got on the track of these findings during the war. As a Navy commander, he helped pick men for night-flying, spotting and gunnery duty. Servicemen at sea, or on sun-drenched coral islands, had to wear dark glasses in daytime if their eyes were to be any good at night.

Last week, Dr. Peckham reported on follow-up studies made during two summers with lifeguards at Atlantic City. What he found convinced him that overexposure of the eyes to bright sunlight creates an alarming problem.

Individuals vary widely, Dr. Peckham found, but on an average, sensitivity to light at night is reduced by more than one-third after a day at the beach without sunglasses; in some cases it is reduced by nine-tenths. The loss in sensitivity cuts down night vision in a "logarithmic proportion": the average driver loses 13% of his visual acuity, the extreme case loses 58%.

In the past, doctors have disagreed as to how long vision is impaired by the sun's glare. Dr. Peckham found from his studies with lifeguards that much of the effect wears off overnight, but in most people some effect persists for two or three days, and in some cases it continues for more than a week.

To prevent both discomfort and danger, Dr. Peckham advises, wear proper sunglasses--"the darker the better." Manufacturers are satisfied if their glasses cut out one-third of the light rays; some ophthalmologists now suggest cutting out as much as 80% to 90%. (The Navy issued some sunglasses which cut out 88%.) Dark glasses need not make it harder to see objects in bright light; they may help when much of the light is unnecessary. Advertising boasts of filtering out "harmful rays," says Dr. Peckham, are meaningless. Under ordinary conditions, he continues, infrared and ultraviolet rays, both invisible, make little difference; visible rays are the ones that do the damage.

Although cheap glasses may not fit well, and their flat lenses are not so easy on the eyes as more expensive, curved lenses, they nonetheless serve their purpose according to Dr. Peckham. Says he: "I have no objection to people buying $5 sunglasses, but I do object to their being told that 18-c- glasses will harm them."

*Bright light bleaches the visual purple, a pigment in the retina which is needed for vision in dim light. Overexposure slows the retina's power to restore the purple when needed.

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