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Autor: reviewessays • February 10, 2011 • 1,926 Words (8 Pages) • 450 Views
Keratoconus is a disease of the eye that is common sometimes. This syndrome can affect many people who can have very serious problem. There are many different backgrounds of the keratoconus such as history, what is keratoconus, causes of the diseases, symptoms, signs and diagnosis, and other treatments.
Keratoconus was the first study by German oculist, Burchard Mauchart in a 1748, which he called staphyloma diaphnum. However, physician John Nottingham clearly described keratoconus as the cases of conical cornea and also he described several classical features of the diseases such as polyopia, weakness of the cornea, and difficulty matching corrective lenses to the patients vision. In 1859, a British surgeon named William Bowman to diagnose keratoconus used an ophthalmoscope to see the conical shape of the cornea. According to Wikipedia encyclopedia, Bowman also attempted to restore the vision by pulling on the iris with a fine hook inserted through the cornea and stretching the pupil into a vertical stenopeic slit like that of a cat. Bowman had a good success with that technique, as an example he restorted vision to an 18 year old woman who had previously been unable to count fingers at a distance of 8 inches (20cm). In 1888, the treatment of Keratoconus became one of the first practical applications of the newly invented contact lens, when the French physician Eugene Kalt manufactured a glass scleral shell, which improved vision by compressing the cornea into in more regular shape (Wikipidia 2). From that time, research of keratoconus has improved understanding of the disease and greatly expanded the choice of the treatment options.
Keratoconus is an eye condition named after the Greek Terms "kerato" which means cornea, and "conus" meaning cone, which also can be hearing a conical cornea (Wikipedia 1). There are three ecstatic corneal dystrophies such as Keratoconus, Kertoglobus, and Pellucid Marginal Corneal Degeneration. Out of three Keratoconus is more common. The cornea is normally a round or spherical shape, but with keratoconus the cornea blurs, distorts and assumes more of the cone shape. It is a disease that leads to the stromal thinning and the bowing forward of the affected cornea which may result in irregular myopic astigmatism, distortion of vision, increased sensitivity to glare and light and an associated reduction in visual acuity. It usually happens around puberty and then it becomes worse during the teens and the mid-20's and becomes stable by the late 20's. According to Angeles Vision Clinic article, "Over 90% of patients have involvement of both eyes, though it is not unusual for there to be asymmetric changes, with one eye being more involved than the other." However, each eye can be affected differently which can result in dramatic decrease in the ability to see clearly even with corrective lenses.
In a fact, about 1/2000 people will develop keratoconus. Most people will have a mild or moderate form of the disease. Less than 10% of keratoconics will develop the most severe form. However, many people have diagnosed in their mid to late thirties; this is usually a more mild form of the diseases. It's very common for one eye to precede faster than the other is, then it changes dramatically over a period of month.
The sign and symptom of kerataconus can be difficult to detect, because it comes on slowly. Nearsightedness and astigmatism also accompany this decease, so patient may have destroyed and blurred vision. According to the Wikipedia article, Keratoconus can be identified by changes in behavior. People suddenly have problems with steps or changes of surface and they don't like go out in the sunshine. That's why we can notice problem with glare and light sensitivity. Keratoconus patients often have prescription changes each time they visit their eye care practitioner. It's not usual to have a delayed diagnosis of keratoconus if the practitioner is not familiar with the early stage symptoms of the decease. Kerataconus patients also often report multiple images or ghosting of images, which is known as monocular polyopia, and often relate a history of frequent refractive correction changes without much improvement in visual acuity. Instead of seeing just one point, a person with keratoconus sees many images of the point that is spread out in a chaotic pattern. Patients may also report irritating symptoms such as intolerance to glare, photophobia (light sensitivity) and recurrent foreign body sensations.
There are more signs of Keratoconus than there are symptoms. The Wikipedia article says that the disease is usually bilateral, but may be quite Asymmetric. The corneal thinning and ectasia happens in three main parts: a nipple cone, where the cone is a small and centered on or near the center of the cornea; an oval cone, where the affected area is larger and usually centered infer temporally; and a globus cone, where the area of involvement covers most of the central cornea. The names of these signs are Vogt's Striae, which is seen by deep stromal usually vertical stress lines at the apex of the cone. Munson's sign is building forward of the inferior eyelid on down gaze. Fleischer ring is an epithelial iron deposition in a ring around the cone.
Keratoconus is caused by weakening of the cornea. It causes the outward flange and thinning of the cornea. According to an article by Keratoconus Inserts, the cause of the weakening is due to an imbalance of enzymes within the cornea itself that leads to high levels of damaging reactive species chemicals. There are different types of reactive species include super oxides, hydrogen peroxide, and nitric oxide. These free radicals can cause oxidative damage to the cornea. There are some genetic reasons explaining why the good enzymes do not functions properly. Non-genetic sources can also increase the reactive species such as ultraviolet light sun exposure, eye rubbing, poorly fit contact lenses, and chronic eye irritation. As a response from Keratoconus Inserts, "all patients with keratoconus has to protect their eyes by wearing100% UV blocking sunglasses with the wrap-around design which minimizes light coming in from the sides." Keratoconus occurs in females slightly more than in males. One long-term study indicates a prevalence of 54.5diagnosescauses of keratoconus per100.000population. Keratoconus has been found with other medical disorders such as atopic disease, Down's syndrome, Ehlers-Danlos syndrome, and Marfan's syndrome.
Keratoconus has two main stages, which is mild (beginning stage), and severe (condition). In the early stages of keratoconus, eyeglasses or soft contact lenses may be used to correct the mild nearsightedness and astigmatism. But as the decease progresses and the cornea