Aging Eyes Blamed For Seniors' Health Woes 149
Hugh Pickens writes "Scientists have looked for explanations as to why certain conditions occur with age, among them memory loss, slower reaction time, insomnia and even depression looking at such suspects as high cholesterol, obesity, heart disease and an inactive lifestyle. Now Laurie Tarkan writes that as eyes age, less and less sunlight gets through the lens to reach key cells in the retina that regulate the body's circadian rhythm, its internal clock that rallies the body to tackle the day's demands in the morning and slows it down at night, allowing the body to rest and repair. 'Evolution has built this beautiful timekeeping mechanism, but the clock is not absolutely perfect and needs to be nudged every day,' says Dr. David Berson, whose lab at Brown University studies how the eye communicates with the brain. Dr. Patricia Turner, an ophthalmologist who with her husband, Dr. Martin Mainster has written extensively about the effects of the aging eye on health, estimate that by age 45, the photoreceptors of the average adult receive just 50 percent of the light needed to fully stimulate the circadian system, by age 55, it dips to 37 percent, and by age 75, to a mere 17 percent and recommend that people should make an effort to expose themselves to bright sunlight or bright indoor lighting when they cannot get outdoors and have installed skylights and extra fluorescent lights in their own offices to help offset the aging of their own eyes. 'In modern society, most of the time we live in a controlled environment under artificial lights, which are 1,000 to 10,000 times dimmer than sunlight and the wrong part of the spectrum,' says Turner. 'We believe the effect is huge and that it's just beginning to be recognized as a problem.'"
It's simpler than that.... (Score:5, Informative)
I had cataract surgery in my left eye (which is the dominant eye) four years ago, at age 49. I had cataract surgery in the right eye 18 months later.
Simply put--as your eyes cloud over, your brain has to work substantially harder to compensate. Your brain has to decipher blurred vision, compensate for the "halo" effect cataracts give you around bright lights (the reason why older people don't drive at night is the halo effect of oncoming headlights--completely blinding them).
All of that changes with cataract surgery--you don't just see better. (And you see MUCH better--if you wore corrective lenses beforehand they implant a custom-fit lens that corrects your vision to 20/20 or better.) All of the "clock cycles" that your brain was devoting to countering the effects of cataracts (even things like keeping your balance) are all of a sudden freed up. The change is dramatic--it really is life-transforming.
My mother-in-law is 90--she had cataract surgery last fall. Last summer, before the surgery, her daughters were wondering about "what are we going to do about Mom"--at the time I suggested that they wait till after the cataract surgery; I was sure it would have a big impact. Boy, did it--my mother-in-law is active, alert, far more capable, and busy with plans for an expanded vegetable garden this summer.
Until you go through the experience, you can't really understand how much effort your brain puts into interpreting what you see. The impact of cataract surgery is unbelievable.
Re:I always thought it was the other way around... (Score:5, Informative)
Re:Does staring at a Computer Screen all day count (Score:5, Informative)
Cataracts are one possible effect; clouding of the lens due to exposure to bands of UV light. Certain medication can also contribute to the effects of light on the eye, but the common one that many people use without knowing the potential effect is St. John's Wort.
I'm profoundly affected by the shortened (and usually sunless) days beginning in the fall, through the awful winter, and into the spring. (I'm self-diagnosing, but I'd say it qualifies as SAD [nih.gov].) I've used St. John's Wort in the winter months with a reasonable degree of success, but I think adding bright light to my work area helped a lot more. As in, four 300W fluorescent bulbs.
Much to my chagrin, however, I learned that St. John's Wort and Bright Light don't Mix [fordham.edu].
Cataracts are (generally) easily treated, thankfully, but that might not be the extent of the possible effect. And I don't particularly want cataracts before I hit 40.
Re:I always thought it was the other way around... (Score:4, Informative)
Poor summary (Score:4, Informative)
From the original abstract: " A 45-year-old adult retains only half the circadian photoreception of early youth" which the summary translates into: "by age 45, the photoreceptors of the average adult receive just 50 percent of the light needed to fully stimulate the circadian system".
Sigh.
Re:Basement lighting (Score:5, Informative)
The question of those born blind and with disease of the retinas does need to be answered. Of course, a lot of blind people do retain some residual awareness of light and dark and still others might have an in-tact pathway to the SCM while having no conscious awareness of it.
Total blindness certainly DOES cause disruptions of body circadian rhythms. Just Google "blindness circadian" and get an eyeful.
www.ncbi.nlm.nih.gov/pubmed/10085469
www.nejm.org/doi/full/10.1056/NEJM200010123431503
jcem.endojournals.org/content/75/1/127
Those above are just a few of the available references.