When most of us hear aging eyes, we think of wrinkles and crow's feet slowly destroying our beauty and youth. But a new study claims these visible signs of aging are only scratching the surface on the effects of old eyes. As eyes age, the lens yellows and the pupil narrows, causing less and less sunlight to enter the eye. Drs. Mainster and Turner claim that the decrease in received sunlight is messing up the body's circadian clock. Circadian clocks use environmental cues to tell an organism what the time of day is. In humans, this often involves the hormone proteins melatonin, which is the body's time-to-sleep hormone and is suppressed by direct light, and cortisol, its wake-up hormone which is activated by light. Previously, it was thought that the only the retina contained light-responsive cells, namely the well-known rods and cones responsible for regular vision. However, in 2002, Dr. Berson and his team showed that a second type of light-responsive cells exist, which they called the retinal ganglion cells. These cells are particularly sensitive to blue light, and melatonin is most severely downregulated by blue light. Decreases in melatonin in people with abnormal sleep schedules, such as shift workers, have been linked to illnesses like heart disease, ulcers, and cancer. Turns out, as eyes age, the first color of light to go is blue. Older folks need more blue light in order to "turn off" their melatonin and restore the proper circadian rhythms, and disturbances in melatonin levels can lead to serious diseases like heart disease and cancer, both of which overwhelmingly impact older people.
Turner and Mainster think the wave of the future is going to be cataract surgery to replace old, clouded lenses, and that this surgery will result in decreased cancer and heart disease. They have also taken measures in their own office to counteract eye aging by installing skylights and extra fluorescent lights.
Personally, this worries me. Shift workers are already generally lower class than people who ordinarily work daytime, because people who have better options don't like operating on a Dracula-esque schedule. If this turns out to be true and a significant factor in heart disease and cancer, the only people who can afford cataract surgery are also upper-class, who are already at a lower health risk for many of these diseases. Would this treatment eventually only widen the health divide between the wealthy and poor? Maybe, I'll get back to you on that once my skylight is installed.