Why do we see on some days worse than on others?
by Dan Roberts
Editor-in-Chief, Low Vision Resources
Gradual vision loss is to be expected with age-related macular degeneration (AMD). Even though it is expected, however, slow deterioration of our view of the world can cause fear, depression, and chronic stress in those of us who must constantly deal with it.
To compound the emotional response, we can become overly-sensitive to changes in our already compromised vision. We might think that every visual anomaly is a sign of further degeneration of our retina, but such is not always the case. In addition to the unfortunate normal course of the disease, several factors can cause our vision to diminish. These conditions are usually treatable, or at least manageable, after which our vision may improve. In other words, they do not cause permanent harm to the retina. If, however, vision does not improve when things return to normal, and if we see new symptoms like dim spots or distortion, that’s when we need to call our eye specialist.
So, unless changes in our eyesight are persistent and severe, complete exams are necessary no more often than every 6-12 months. For that matter, the eye doctor’s use of a slit lamp, plus the bright light flashes from fundus photos, can actually cause damage to the photoreceptor cells if used frequently over time. OCT scans can be done with little risk, but, without additional information from the photos and slit lamp exams (or better yet, use of a non-mydriatic camera), those alone would be of little value to a person with dry AMD.
Visual changes are more noticeable to us than they are to people with normal vision. We are walking closer to the edge of the cliff, so it doesn’t take much to topple us over. We are also more aware, thus more concerned, about losing our vision. Simple things like going to an unfamiliar place or waking up to a cloudy day, can diminish our visual perception and cause us undue concern.
We see worse on a cloudy day than on a sunny day. On the other hand, we see poorly on a sunny day if we encounter glare. The kinds of task lamps and ambient lighting in our homes can also affect our vision. To maximize our vision, we need to learn about proper lenses and lighting instruments.
Hormonal changes, such as during pregnancy or menopause, raises levels of glucocorticoids, which have been linked to central vision loss.
A poor night’s sleep cuts short the visual cycle, during which the sight cells are allowed to recover from the effects of daylight.
Even a simple cold can lower resistance levels and decrease the effectiveness of the immune system. And to compound the problem, side effects of certain medications can decrease visual acuity.
We become accustomed to our normal environment, to the extent that we often use our memories more than our eyesight to get around. Then, when we make a trip to an unfamiliar place, memory cannot serve us, forcing us to remember that our vision is not as good as it used to be.
Other ophthalmic conditions
Dry eye, cataract, inflammation, or infection can also deteriorate our eyesight. We need to consider all possible reasons for our our changing vision. It may be something that can be corrected. And we must always consider the chance that an improved spectacle prescription might still help us see better.
Fear, depression, and stress are normal reactions as our eyesight diminishes, but it is helpful for us to know that some vision loss is only temporary. We must also keep in mind that, even as our sight cells gradually cease to function from the effects of the disease, AMD alone will never affect more than the center 35% of our visual field. We have an amazing ability to adapt, and almost all of our normal daily activities can still be accomplished in spite of vision loss. Remembering this, and staying in touch with good information and support, will go a long way in helping us ride the AMD roller coaster.