Keratoconus is a disease in which the cornea – the first lens of the eye – undergoes progressive thinning, loses its spherical shape and acquires a conical shape. It is usually bilateral, but asymmetrical and progressive.
What causes keratoconus?
Keratoconus is caused by a weakness of the collagen – the fibers that make up the cornea – which is unable to withstand the pressure inside the eye, causing it to elongate forward.
Although the cause of the weakness is not entirely clear, genetic, environmental and patient-specific factors such as eye rubbing or atopy have been implicated. Up to 50% of patients with keratoconus rub their eyes vigorously.
What are the symptoms of keratoconus?
The disease usually manifests in adolescence, and progresses until the third or fourth decade of life, with a slower progression from then on. It begins with unstable myopia and astigmatism, with patients being difficult to prescribe and having their prescription changed from time to time. At first, visual acuity may be normal, but as the disease progresses, visual acuity decreases and does not improve with prescription.
How is keratoconus treated?
In the first phase, with small cones in which progression is observed, treatment with crosslinking is indicated. This treatment consists of “freezing” the cornea, hardening it with Riboflavin and ultraviolent radiation to prevent cone progression.
In more advanced cases in which there is great deformity or visual acuity is compromised, the treatment consists of intrastromal rings. These are devices that are placed inside the cornea to strengthen it and prevent further thinning.
In late stages of the disease, when the cornea is too thin or there is scarring, the treatment of choice is transplantation. Nowadays, the ophthalmologist can transplant only the affected area, preserving parts of the patient’s healthy cornea. In general, patients with keratoconus are usually patients with a good prognosis for transplantation.