Big ‘E’ Eye Charts Fading Away as Electronics Come Into View

When the big “E” eye chart was developed in the candle-lighted 1860s by a Dutch ophthalmologist, anyone could memorize the sequence and claim to have perfect eyesight.

Eye specialists can now jumble the sequence of letters with push-button projectors, but the dim-to-dark rooms used for visual testing are still common--a factor that two Orange County physicians say leaves vision testing in the 19th Century.

Drs. Clifford and Joy Terry have combined their skills as physicians and expertise in electronics to invent a computerized system that they say simulates conditions for night or daytime driving and can test and entertain preschool children.

In short, they say, they have brought the vision exam into the age of high technology.

Before Freeways

“When Snellen standardized the eye chart in the 1860s, there was no freeway driving, there weren’t even any electric lights, so the chart tested vision in accordance with the best technology of the time--a printed chart and a room lit by candle,” Joy Terry said.

The Snellen chart for the first time measured the size of letters visible at given distances to determine visual acuity, measurements that are still in use today, she explained.

Although the way in which the eye and brain processes information has not evolved, the things that people see have changed dramatically and created problems with eyesight never encountered in 19th-Century Amsterdam.

“Take freeway driving and trying to read highway signs at night,” Terry said. “Some people have difficulty seeing and reading the signs, even though they may otherwise have good vision.”

Simulates Glare

The Terrys’ computer can simulate the glare of oncoming headlights into the eyes of the person being tested, enabling the doctor to determine whether two pair of glasses--one for day and another for night--are necessary.

“Bright traffic lights are not the only problem with glare,” Terry said. “Some people have vision problems in bright sunlight, but in a dim testing situation they would appear to have near normal vision.”

Terry said when the eyesight test is conducted in dim light, people with glare problems are being examined under conditions in which their eyesight is at its best, when there is no glare, there is no problem.

“What the computer does, in addition to the light, is correlate the size of letters on a highway sign to the distance it would take a person traveling 55 m.p.h. to read the sign.