I spent the morning at my kids’ school today reorganizing the library shelves. I was nearly dizzy when I left. I didn’t read any books while I was there but, I still learned several things. There are an inordinate amount of picture books about reptiles and they are all filed under 591.323. Despite the fact that I sing the ABCs two hundred times a day, I have yet to master it. And, my arms have shrunk, which is disappointing on many levels. Is it just me or is the written word getting smaller and slightly blurrier?
There are many different type of visual impairment.
1. Myopia (nearsightedness) is a condition in which a person is able to see objects that are close but has difficulty seeing objects that are far away. Myopia is very common in children and is usually diagnosed when they have difficulty reading the blackboard.
2. Hyperopia (farsightedness) is the opposite. It is most common in people over 40 years old and progresses with age. In the big plan of things, we should have been eaten by a dinosaur in our early 30s. Lots of things start to go south after this age. At least when you have hyperopia, the wrinkles and age spots are harder to see.
These two conditions are caused by abnormalities in the shape of the cornea. (See yesterday’s entry for descriptions of the parts of the eye.) The altered shape directs the light either in front of or behind the retina instead of directly on it — where it needs to land for perfect vision. Eyeglasses or contacts make up for the corneal problem by redirecting the light through the pupil so that it lands where it should.
3. Presbyopia – This is the condition I think I am experiencing. My arms are simply not long enough anymore. With age, the lens of the eye hardens and the muscle fibers around the lens become less effective, making it hard to focus on objects that are close. It is most common in people over the age of 35 – remember, evolution didn’t address long-lasting lenses because a T-Rex should have made a meal of you by now. The simplest treatment is eyeglasses.
4. Cataracts – Another perk of aging is that the lens of the eye changes its make up over time. Just as your skin loses its elasticity, the lens can become cloudy. A cloudy lens is similar to what you see through your sunglasses after your child has played with them. The smudges result in a blurred image. By the age of 80, about 50% of people have had cataracts or cataract surgery. In addition to age, other risk factors for the development of cataracts have been identified including diabetes, smoking, alcohol use and prolonged exposure to bright sun. Cataract surgery involves removing the lens and replacing it with an artificial one.
5. Age-related macular degeneration (AMD) is one of the most common types of vision impairment in people over 60, resulting in the loss of the center part of your visual field. As you might imagine, the center part is fairly important, as it would be very hard to drive or walk with a big hole in the middle of your line of sight. The macula is a small area on the retina that allows you to see fine detail. There are two types of AMD – wet and dry. Wet AMD occurs because of changes in the blood vessels that supply the retina. It can progress very rapidly. The initial symptom may be that straight lines appear wavy. Dry AMD is a problem with the cells that make up the macula. It can occur more slowly with initial symptoms of needing more light for reading and difficulty recognizing faces.
There are other types of visual loss, some of which will be addressed on Friday under serious eye conditions – not that the above are not serious. Eye health should be a priority. In addition to getting yearly eye exams, you should provide yourself with good lighting when reading, avoid bright sunlight, get good nutrition and give your eyes frequent breaks from computer screens and TVs. There may, after all, be some things you want to see in your old age; your grandchildren, sunsets, the Sports Illustrated swimsuit issue, and Charlie Sheen when he gets out of rehab at the tender age of 85 — to name just a few.