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Nizoral (Ketoconazole)

###table###Nizoral(Ketoconazole)
SENSE ORGANS: SIGHT AS A PROCESS
The picturesque name, cataract, developed because a film seemed to “drop” down over the sight, obscuring vision. Occasionally cataracts appear in the newborn infant; sometimes they follow as the result of disease or injury of the eye. By far the most common is the senile cataract, developing usually after middle age and seemingly a part of the aging process. Fortunately a great many such cataracts develop slowly and in one eye more than the other. The duty of the ophthalmologist is to judge whether the patient is getting along well with the better eye and when the cataract is “ripened,” that is, in the best condition for removing. When the proper time has arrived and the operation has been well done, then powerful glasses may give good vision.
So far the apparatus for handling the organ of sight has been described. The real sense organ is the retina, covering about two-thirds of the inner wall of the eyeball. The other sense organs of the body are formed at the ends of nerves. The sensory part of the retina and the optic nerve itself are really an out-pushing of the brain. It is decidedly different from anything else in the body. There are said to be seven million cones in the retina and one hundred million rods. Cones register the different colors, while the rods give us colorless vision even with poor light.
Strangely enough, sight is a chemical process. There is formed in the retina a substance called visual purple. In recent years it has been found that the visual purple cannot be produced in the absence of Vitamin A. Hence night blindness is a striking symptom of this avitaminosis. Knowledge of this phemonon has contributed to the art of the X-ray specialist. These physicians do some of their most important work in the dark room, studying faint shadows on the fluoroscopic screen. Light uses up the visual purple quickly. With plenty of daylight we see well enough, but we seem almost blind when we first enter a dimly lighted movie house. Some of this is due, of course, to the contraction of our pupils. So after lunch my friend Dr. В., the roentgenologist, puts on dark red glasses. These allow the visual purple to accumulate and the pupils to open wide. If he has plenty of time he spends a few minutes in the absolute darkness of the examining room before he begins, with the eyes of an owl, to look at the screen.
There is another way in which sight fatigue may be demonstrated. After you have looked for a while at a brilliantly colored landscape, turn your back on it, stoop over, and survey it between your legs. The increased brightness of the colors will reward you for the undignified attitude that you have assumed. You are using another part of your retina where the visual purple has not been so much used up.
Helmholtz, who thought that he could design a better eye than the one we use, was really one of the greatest of scientists. Among his many achievements was the invention of the ophthalmoscope. This device consists of a circular mirror with an electric light bulb placed at its center so that the light is reflected into the interior of the patient’s eye through the pupil. At the upper edge of the mirror is an opening through which the posterior, internal surface of the eyeball can be viewed.
Attached to the machine is a disk which allows any one of a series of lenses to be placed over the opening, thus bringing the retina into exact focus. To the modern physician the ophthalmoscope may be as valuable as the stethoscope. Many abnormal conditions in the body – diabetes, kidney disease, high blood pressure, and brain tumors, for example – cause changes in the eye, chiefly in the blood vessels. This gives valuable clues in diagnosis.
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