Month: May 2010

What causes keratoconus?

The causes of this condition are still unknown despite our familiarity with this disease. There have been many studies and there have been many theories.

One proposal suggests that orange county keratoconus depends on a defect in the development and genetic (about 7% of patients have relatives with keratoconus). This suggests that the consequence of an abnormality in growth, essentially a birth defect. Another is that Keratoconus is a degenerative condition. A third postulated that keratoconus is secondary to other diseases. A less accepted theory suggests it may be of endocrine origin.

The actual incidence of orange county keratoconus is not known. It is one of the most common afflictions of the eye but it is by no means a rare disease. Is estimated to occur once in every two thousand people. Usually the disease occurs in young people at puberty. It is found everywhere in the world without follow any geographical pattern, cultural or social acquaintance. Several sources suggest that keratoconus probably arises from a number of different factors: genetic, environmental or cell phone, no one can form the trigger that will initiate the disease. There are also doctors who associate the scratching keratoconus eyes. Often the patient has allergic rhinitis associated with keratoconus, which causes the eyes itch often. This can cause thinning of the cornea due to mechanical removal of epithelial cells.

The visual distortion experienced by the patients come from two sources, one being the irregular deformation of the surface of the cornea, and other scars formed at points of high curvature exposed. These factors act together to form regions on the cornea which projects an image into different regions of the retina and cause the symptoms of monocular diplopia or monocular poliplopia. The effect can worsen in low light because the pupil tends to dilate in order to receive more light, and thus further exposing the irregularities of the cornea. Scars seem to be an aspect of the degradation of the cornea, however, a large multi-center study conducted (Clek STUDY – Collaborative Longitudinal Evaluation of Keratoconus Study) suggests that the abrasion caused by contact lenses may increase the tendency of this finding on one factor above two, or more than double the chance of occurrence.

Recent studies have shown that orange county keratoconus corneas show signs of increased activity of proteases, a class of enzymes that break part of the collagen fibers in the corneal stroma, with a simultaneous significant reduction of the action of protease inhibitors. Other studies have suggested that the reduction of activity by the enzyme aldehyde dehydrogenase may be responsible for the creation of free radicals and oxidant species in the cornea. It is quite likely that whatever the pathogenic process, the damage caused by activities in the cornea resulting in reduction of its ultrasound pachymetry and weakening their resistance biomechanics.

A genetic predisposition for keratoconus has been observed, with the disease manifesting itself in certain families, and reported incidences of concordance in identical twins. The frequency of occurrence in close relatives is not clearly defined, although it is known that the incidence is considerably higher than in the general population, and studies have obtained estimates ranging between 6% and 19%. The gene responsible for keratoconus has not been identified: two large studies involving isolated communities homogenéticas contrary has indicated as causes of genetic disease mapped to chromosomes 16q and 20q. However, most genetic studies agree on a model autosome dominant hereditary. Keratoconus is also diagnosed more often in people with Down syndrome, although the reasons for this link have not yet been determined. Keratoconus has been associated with atopic diseases. including asthma, allergies and eczema, and it is not uncommon for many or some of these diseases affect a person. Studies suggest that rubbing the eyes vigorously may contribute to the progression of keratoconus, and patients should be discouraged from this practice.