Why Vision Declines with Age

The onward march of time is relentless and unstoppable. For some, age creeps up slowly; for others, one day you’re loving life in your mid-twenties and the next day you’re waking up with back pain and stiff knees, not to mention those new gray hairs. Unfortunately, even our eyes and vision cannot escape the inevitable, but knowing what are expected changes to vision with age can help you prepare (at least emotionally).

Why age affects our ability to focus on near objects
One of the first signs of aging eyes is the decline in the ability to focus on near objects. The medical term for this is presbyopia, which is derived from the unflattering Greek phrase “old eye.” Inside the eye just behind the colored iris is a crystalline lens. In younger individuals, this lens is flexible and its ability to change shape, controlled by a ring of muscle called the ciliary muscle, enables us to focus on near objects, such as during reading, checking your watch, chopping vegetables, or applying nail polish. As we celebrate birthday after birthday, this crystalline lens becomes increasingly stiffer (and thicker) and more effort must be exerted by the ciliary muscle to adjust the lens to change focus. It is usually around the mid-forties that most patients realize their reading vision isn’t what it used to be. It’s at this point that it can get a little complicated to explain the situation, depending on the patient’s distance vision.

Myopia (short-sightedness)
Patients who are myopic, or short-sighted, have a natural ability to focus at near lengths when they are not wearing any glasses or contact lenses. Of course, this is at the expense of their long-distance vision, which will be blurry if no optical correction is worn. For low to moderate degrees of myopia, patients who enter into presbyopia begin to find that while they could once see both distance and near while leaving their spectacles on, now find that in order to read clearly and comfortably they must take their glasses off. As presbyopia is progressive, the near vision continues to decline until a plateau usually around 60 to 65 years old. For patients with only low myopia, they may find that their natural short-sightedness may eventually not be sufficient to provide comfortable and clear near vision and they will require a reading script in addition to maintaining their distance script.

Hyperopia (long-sightedness)
On the other hand, patients who are hyperopic, or long-sighted, get the short end of the stick because eventually they will find both their near vision and long vision will progressively deteriorate as presbyopia sets in. The reason for this is because an individual who is hyperopic is, in fact, constantly exerting some degree of effort by the ciliary muscle in order to see even long distance clearly. Additional effort is required on top of this to achieve clear near vision. Depending on the degree of hyperopia, difficulties with near vision may become apparent earlier than the typical mid-forties as the crystalline lens just becomes too inflexible to focus at near lengths. In the early days, a distance prescription may be sufficient to alleviate this effort such that reading vision is adequate but eventually a hyperopic patient will require a different prescription for distance and near vision.

Short of finding a treatment for old age, there is currently very little that can be done to slow or reverse the onset or progression of presbyopia. In addition to the traditional glasses or contact lenses, there are a few surgical treatments that can help to provide reasonable distance and near vision, such as multifocal intraocular lens implants or monovision lens implants (one eye is corrected with a distance vision implant and the other with a near vision implant), or certain laser eye surgery procedures, such as blended LASIK. A few pharmaceutical companies are also currently in the process of developing eye drops to improve near vision with varying mechanisms of action, including an attempt to restore the flexibility of the crystalline lens.

Many older patients are aghast to be told by their eye doctor that they have the beginnings of an early cataract. Panic and anxiety may set in – am I going to go blind? The good news is no, you’re not going to go blind; though cataracts are often cited as the most common cause of blindness, this is because many developing countries do not have access to sight-restoring cataract surgery, a procedure that is performed in the US almost 4 million times every year. The other good news (or maybe bad news, depending on how you look at it) is that cataracts are as normal and inevitable as wrinkles and white hair. Age and ultraviolet light exposure over one’s lifetime are the typical culprits of cataract development, with high UV exposure found to be linked to an earlier onset of cataract and more rapid progression. Certain diets high in antixoidants such as vitamins A and C may help to delay the onset of cataract but it is safe to say that if you live long enough, you will develop some degree of cataract.

A cataract refers to any loss of transparency of the crystalline lens inside the eye. There is no pain or eye irritation as a result of cataract and it typically cannot be observed just by looking into a mirror. Cataracts result in degradation of the vision, though this may not be noticeable or bothersome in the early or even moderate stages. Individuals with cataract may also notice an increase in their dependency on good lighting to discern fine detail at near lengths, such as reading or threading a needle, and may also become more glare sensitive, such as during night-time driving. A progressive cataract may cause a change in the prescription of your glasses or contact lenses and a simple update to your glasses can restore your vision to acceptable clarity, however, eventually a cataract may advance to a stage where surgical removal is necessary to achieve any significant improvement in vision.

Dry eye
Ask any menopausal woman and you’ll be told that things seem to be getting… well, a bit dry. Dry eye disease, that burning, stinging, gritty, irritated feeling in the eyes, is found at higher rates in individuals over 50 years old and in females. It doesn’t mean that men or younger patients won’t experience dry eye but these populations are less likely to be affected.

Researchers aren’t yet fully clear on why older women are the most susceptible group to fall prey to dry eye disease but it is thought that the sex hormones estrogen and progesterone play a role. Estrogen levels tend to fluctuate throughout a women’s menstrual cycle during her childbearing years but will wreak the most havoc during that delightful time known as menopause.

Depending on the severity of the eye dryness and its impact on quality of life, various treatments are available but there is currently nothing that would be considered a “cure.” Artificial tear lubricants, nutritional supplements, IPL treatment, and even Manuka honey eye gel have been shown to be beneficial for improving dry eyes in both men and women.

Eye disease risk
Numerous eye diseases will cite increasing age as a risk factor. The two big ones are age-related macular degeneration (the name more or less speaks for itself with this one), which involves damage and degeneration to the area of the retina that receives central vision; and glaucoma, a disease of the optic nerve as a result of the pressure within the eye being too high. Cataract and dry eye disease are two other common age-related eye problems already mentioned above.

Macular degeneration is a multifactorial disease, thought to be a result of inflammation, ultraviolet exposure and oxidative damage, and accumulation of metabolic waste material. In short, the tissues of the aging retina are not doing what they’re supposed to be doing as effectively as they’re supposed to be doing it. Damage to the supportive tissues of the macula in the eye eventually lead to degeneration and atrophy of the macula itself, which can impair the central vision. Though there is no proven treatment that can reverse the effects of macular degeneration, a healthy diet high in antioxidants, or scientifically-backed nutritional supplements, are found to help slow the progression of this disease. For a certain form of macular degeneration known as the neovascular, or wet, stage, eye injections are currently the treatment of choice to prevent progressive damage.

The resilience of the optic nerve diminishes with age, making it more vulnerable to damage from fluctuations in eye pressure. In addition to this, eye pressure may have a tendency to rise with increasing age as the mechanisms that control the balance of fluid production and drainage in the eye begin to work less optimally. In addition to other changes to the eye with age, these two factors contribute to the increased glaucoma risk of an older eye. If glaucoma is not caught and treated early enough, or if treatment fails to stop its progression, it can result in permanent peripheral vision loss. Very advanced cases of glaucoma may also involve central vision loss. Though glaucoma can often be successfully treated with pressure-lowering eye drops, laser procedures, or surgical methods, any vision loss is not recoverable so early detection with regular eye tests is important.

Though the pervading theme of this article may be the unstoppable progression of age and its effects on your eyes and vision, getting older (and old) happens to the best of us so don’t feel too bad about it. Just think about all that life wisdom you’re accumulating.