When the doctor told you that you needed bifocals, you may have protested (verbally or only mentally) that you weren’t that old. Actually, you probably weren’t, even though a few grey hairs may have started to show up here and there. The average person begins to need bifocals in their 40s, and then only if he or she does reading or close work. Five hundred years ago when most people where illiterate and/or occupied with farming, bifocals were not necessary. (The life span was much shorter, too.) Today, they are almost indispensable. Read the rest of this entry »
You were probably not too thrilled the first time you were told you needed glasses, but as long as you must wear them, why not learn how they work? Obviously, glasses are made up of lenses and a frame. The frame can be made of plastic, metal, or a combination of the two; its function is to keep the lenses positioned in front of your eyes. The part that sits on the bridge of your nose Ls called, quite logically, the “bridge,” and the handles which it on your ears are called “temples.” Read the rest of this entry »
Lens powers are measured in diopters. The higher the number, the stronger the lens. Plus signs ( + ) are used to indicate reading glasses or magnifying lenses. Minus signs ( — ) are used for indicating distance or reducing lenses. Read the rest of this entry »
Symptoms
All the symptoms of cataract are visual, the usual complaint being of a general mistiness of sight, more particularly for distance vision, as reading is often unaffected in the earlier stages. One eye is frequently worse than its fellow, but sooner or later both eyes alter. At this stage dazzle may be a cause of great distress. In normal lighting conditions vision may not be seriously disturbed, but in bright sunlight it becomes obscured by dazzle in the same way that a dirty windscreen becomes almost opaque in the headlights of oncoming cars. In this situation patients may be greatly helped by wearing a brimmed hat or tennis shade. Tinted glasses are of limited assistance because it is the direction of the light as much as its brilliance that causes the trouble. Read the rest of this entry »
These then are the common errors of vision which may cause eye-strain. They are short- and long-sightedness, near-vision deficiency and astigmatism. Most commonly astigmatism is present with one of the other three conditions. They may all be measured by both objective and subjective methods. Objective measurement means the use of instruments, while subjective measurement requires you to state an opinion. In ordinary practice the practitioner will use both methods, and thereby establish a pattern which enables him to prescribe the right optical correction. If you repeatedly give a wrong answer to a subjective inquiry the experienced occulist will proceed to further objective (optometrical) tests. Read the rest of this entry »
Why did the dinosaurs become extinct? A recently advanced theory suggests, not altogether implausibly, that they died out because of cataract. Sudden changes in the earth’s atmosphere meant that rays harmful to dinosaurian eyes reached down to the forests and plains from the sun. It happened so quickly that evolution had no time to mount a defence.
Cataract, among such mammals as humans, is a condition where the inner crystalline lens of the eye has lost its transparency, and therefore its optical value. Opacities of the inner lens are often present from birth, in the form of small dots, and in no way seriously affect the individual’s vision. Indeed, many people have such dots but are unaware of their presence. Read the rest of this entry »
As regards lens-implant surgery the benefits are very great. To be able to have normal sight again without the need for thick spectacles or the bother of wearing contact lenses is surely the preferred treatment. Where contact lenses are used subsequent to a cataract operation, they differ from ordinary contact lenses in certain ways. The condition of an eye that has had its crystalline lens removed is known as aphakia, and aphakia almost invariably demands a contact lens that is much thicker in its centre than the lens worn by the ordinary short-sighted person. Read the rest of this entry »
The retina, then, is a nerve pad dependent upon a complex network of support systems. One of these support systems is a supply of blood, for it is in the blood that many of the essential nutrients are carried from one part of the body to another. Therefore the eye, and more particularly the retina, is or can be affected by deficiencies in other organs. The retina is in fact fed by blood systems both in front and behind, and many blood diseases can have a deleterious effect on retinal functions; and both systems are sufficiently intricate and fine to be hypersensitive to abnormalities in the blood. However, since the variations and permutations of retinal degeneracy are enormous it is sometimes very difficult to diagnose its cause. It is always possible to describe what one sees as being wrong with a decayed retina, but even after many specialized tests it can still be impossible to say with any accuracy what is the precise cause. This has seriously hampered the treatment of some retinal conditions. Where the cause of a disease is known it is always much easier to prescribe a cure, or at least medication that will halt or slow down what is usually a progressive condition. Read the rest of this entry »
The greater the ophthalmologist’s knowledge of general disorders, the more help he will be in their diagnosis, or at least in making a wise referral. And this applies as much to nervous disorders as it does to diseases in the blood. The central nervous system is necessarily and intimately connected with the eye and vision, which are therefore affected by nerve and brain abnormalities. Read the rest of this entry »
This not always possible for people to go to a competent I physician for relief. As the method of treating eye defects presented is comparatively new, it may be impossible to find a physician in the neighborhood who understands it, and a person may not be able to afford the expense of a long journey or take the time for treatment away from home. To such persons I wish to say that it is possible for a large number of people to correct defective eyesight without the aid either of a physician or of anyone else. Read the rest of this entry »
