Old age isn’t always kind to eyes. Even people with 20/20 vision will often see a general decrease of various eyesight and vision attritubes as they get older. This is largely due to a long list of conditions that either become worse or more likely with age. Presbyopia, for example, an impairment of near vision, is literally a combination of Greek terms for “old man” and “sight” (not to exclude women, who also experience it).
Cataracts, age-related macular degeneration, glaucoma, diabetes – all of these pose serious risks to your vision, and all are much, much more likely to hit as we age. And while the news isn’t all bad – nearsighted people will sometimes actually see their vision improve as they grow older – it isn’t, on balance, what we’d call good.
One of the most common and potentially serious changes is a serious loss of contrast vision. However, despite all that, it’s not among the most-talked about changes. We’ll aim to change that here by talking about what contrast sensitivity is, how it changes with age, and what exactly can be done about it.
While we often talk about visual acuity, or the basic accuracy of a person’s eyesight, as a standard of overall vision quality, it’s far from the full story. In fact, plenty of aging individuals can have technically excellent eyesight and still score highly on the Snellen charts used to test it, but still have severely reduced vision in practice.
Contrast sensitivity plays a large part in this. Contrast is, at its most basic definition, the difference between two colors, shades, or tones. When we’re discussing vision, contrast is a huge part of what allows us to identify and distinguish objects from the scenes they’re in.
Think about looking at a city skyline in the morning. You’ll see areas of high contrast where buildings stand out from the blue sky (let’s make our hypothetical day a good one), and areas of low contrast, with buildings in front of or next to other similarly-colored buildings. To actually distinguish where each skyscraper is, your visual system relies on cues such as shadow, tone, and color to decide where one object ends and the other begins.
You can probably see why this is crucial to effective every day vision. It’s one thing to be able to accurately see an approaching car, but what if, due to reduced contrast sensitivity, you were unable to distinguish the car from the road? On a practical level, that’s much the same thing as having extremely poor visual acuity. In both cases, you won’t be able to tell that there’s a car coming or, even if you do notice it because of other visual or audio cues, you won’t be able to tell precisely where it is.
Because of this, contrast sensitivity needs to be understood as an integral part to a healthy visual system. Unfortunately, it’s among the most likely ones to fade with age. Many of the disorders that preferentially affect older people also affect contrast sensitivity. Cataracts are notorious for this. These obscuring proteins reduce the contrast in an affected person’s visual field, making it much more difficult to perceive what remains. Glaucoma is similarly known to decrease contrast vision, as are macular degeneration, Alzheimer’s Disease, and even stroke.
People with decreased sensitivity can have an extremely difficult time perceiving detail around them. Everyday tasks obviously become more difficult, and potentially even dangerous, as in the case of driving. Near-work also suffers and reading can become very laborious and unpleasant, especially if letters aren’t well-contrasted with their background. Falls, injuries, and a decreased quality of life are all possible risks for anyone with severely reduced contrast vision.
Responding to Low Contrast Sensitivity
For anyone having a tougher time perceiving contrast, the first step is to ensure that they can continue to live safely. Hazard-proofing a house is a good idea for folks with reduced vision, no matter the cause, and can make life much easier if done correctly.
When dealing with contrast sensitivity, keep in mind that object distinction is a priority. Use lighting to increase contrast and equip them with timers or easy-access switches as needed. Take special care to illuminate fall hazards such as stairs or thresholds. To build on that, take advantage of contrast rules. If a step is difficult to see even with good lighting, find tape that clashes horrifically with the material the step’s made of. It might not be the most aesthetically pleasing solution, but it’ll go a long way towards making a house safer.
Actually treating age-related contrast sensitivity is another matter entirely. As of now, options are very limited. An intermediate step is the use of high-contrast filters, like those seen in ski goggles. Some people find that blocking certain types of light can help sharpen the visual field, but it’s far from a catch-all solution, and won’t work on everyone.
Luckily, this may change. A recent study conducted on a group of participants with reduced contrast vision found that an eye-training regimen could cause rapid recovery of that aspect of vision. Participants tested themselves on striped images to retrain contrast perception. By the end of it, older adults displayed sensitivity similar to people 40 years younger who had also been involved. While the idea of visual training to effectively treat contrast sensitivity and similar disorders is only just now starting to show promising signs, we hope and expect to see it blossom in the coming years.