FISHERS, Ind. – We all know what a traditional eye test looks like: white letters on a dark background, with the letters diminishing in size.
Dr. Mark Roark has added another tool to his diagnostic evaluations. He wants to know how little contrast or how much contrast it takes for you to see real objects in the real world.
“I give you a certain letter size and I make that letter fainter and fainter on a screen,” said Dr. Roark. “I then ask, ‘when does it disappear? Where is that threshold of just being able to detect it.’ That information gives us a lot of important data about how you’re really seeing when you’re, say, driving at night.”
The exam is relatively quick, taking maybe a minute. Dr. Roark scores your contrast threshold. Normal scores are generally in the 2-2.5 range. 1.6 is excellent. Anything above a 4-5 may need improving.
The contrast threshold score represents the border between the visible and the invisible and tends to drop off much sooner than visual acuity in many disease processes.
“There are studies,” said Dr. Roark, “Showing older Americans who have a lower contrast sensitivity, measured with our test, are more likely to have wrecks, car accidents. It’s been shown they’re more likely to fall. They don’t see as well, as they could.”
Poor contrast sensitivity often leads to complaints of poor night vision and glare. Those symptoms can help eye care professionals diagnose early stages of cataracts, optic nerve problems and even retinal disease.
Dr. Roark believes contrast sensitivity, in and of itself, can be improved through diet.
“We do believe it’s linked to the diet, the amount of pigment as well,” said Dr. Roark.
Dr. Roark believes Americans are in an era of nutrient deficient foodstuffs. The result is our eyes are deficient in what he calls macular carotenoids.
Plants like spinach, kale and colorful bell peppers contain the carotenoids the eyes need, but supplementation may be a more comprehensive answer. Dr. Roark says supplements should contain lutein, meso-zeaxanthin and zeaxanthin, in appropriate doses.
“Studies have been done on patients who didn’t even need glasses and we gave them a supplement and they could see better.”
For more information on contrast sensitivity threshold or CST testing, contact Dr. Roark at the Allisonville Eye Care Center of Fishers. His number is 317-577-0707.