Keratoconus is a disease that makes the cornea change its shape from spherical to conical. Keratoconus is a disease that contributes to astigmatism. This does not mean, however, that any person with this vision defect has a conical cornea, because keratoconus is accompanied by other characteristic symptoms.
It has been observed that people suffering from keratoconus more often than others have red, itchy and dry eyes, have allergic reactions, suffer from chronic nasal sinusitis and hay fever. Specialists haven’t yet determined what are the exact causes of keratoconus. It is believed that keratoconus is a genetically based disease or has something to do with endocrine system disorders.
A healthy cornea is shaped like a segment of a perfect sphere and encloses the front of the eyeball. It is one of the main parts of the optical system, and also has a protective function. Keratoconus is a condition where the cornea’s shape is significantly distorted. These changes usually affect only one eye. Keratoconus grows slowly, but it can also stop. But even a minimalirregularity of the cornea can cause vision deteroration. If it progresses, the cornea continues to bulge – thus becomes thinner, and gradually becomes irregular in shape.
It’s hard to capture the beginning of the deformation of the cornea. The first symptoms of keratoconus is usually redness and itching – can be misdiagnosed as fatigue or allergy. As the disease progresses, the eyes may be sensible to light, causing blubbering, and the halo effect (glow around light sources), double vision and image distortion. Above all, however, rapidly deteriorating eyesight is most common and causes more frequent visits to the ophthalmologist and changing glasses, until choosing the right pair of glasses becomes impossible. Fortunately, you can then take advantage of other methods that will improve your vision.
To test for keratoconus, your eye doctor will check for distorted, blurred vision, sudden changes in one eye’s vision, or double vision when using only one eye and halos around bright lights.
• Slit-lamp examination
• Corneal topography
The most common method to restore good vision is wearing hard, gas permeable contact lenses. Lenses do not cure or totally eliminate keratoconus, they just adjust the curvature. These lenses are made individually for each patient based on a corneal topography. It is a computer-based test, which accurately reproduces the shape of the cornea in the form of a map and help detect any abnormalities.
Lenses must be chosen so that they don’t put too much pressure on the top of the cone so the surface of the cornea isn’t damaged. These lenses create a “space” which is filled with tear fluid, which results in improved visual acuity. Properly selected lenses should work well to an average of 18 months, however due to the fact that the disease will most likely progress – you will need to change them.
Treatment: intacs implantation
A new method of correction of keratoconus is implanting intacs, which are two tiny, clear crescent-shaped pieces of a plastic polymer that are inserted into the cornea to reshape the front surface of the eye. These implants press against the curvature of the cornea, flattening the peak of the cone and restoring it to a more natural, though not perfect, shape.
The procedure is performed under local anesthesia (using drops). It takes only a few minutes, and its effect is almost immediate – a marked improvement in visual acuity. Unfortunately, intacs implantation does not stop the development of eye disease and after some time it may be necessary to exchange the rings and insert new ones in different sizes.
Treatment: corneal cross-linking
This method is in most cases designed for people whose keratoconus is in the early stages of development. Custom-made riboflavin solution drops saturate the cornea, which is then activated by ultraviolet lights. Irradiation lasts approx. 30 minutes. It causes the stimulation of collagen in one of the layers of the cornea, allowing the cornea to recover part of its mechanical strength. Patients have to wait 6-8 months to experience any noticeable effects.
Treatment: corneal transplant
Where other methods of treatment are impossible, a corneal transplant may be the only option. The procedure takes 1-1.5 hours and involves the removal of the irregular portion of the cornea and suturing a matching segment of tissue collected from the recipient. Transplant rejections are very rare (less than 1 per cent.). Unfortunately, there is quite a long recovery period (6-12 months) and usually requires resting, and taking the immunosuppressive drugs.