The transparent, dome-shaped tissue at the front of the eye is called the cornea. Its function is to focus incoming light into the eye. Keratoconus occurs when the cornea thins and bulges forward into a cone shape. This unwanted change disrupts the proper focusing of light, leading to visual impairment. As a result, daily activities such as reading or driving become more difficult.
Keratoconus is a progressive disease that affects both eyes, caused by thinning and forward bulging of the cornea. It is also known among the public as corneal protrusion. In the early stages, rigid gas-permeable contact lenses may be used as a treatment option. However, while contact lenses improve vision by correcting irregular astigmatism, they do not stop disease progression. As the disease advances, contact lenses become insufficient, and vision gradually worsens.
Another treatment option is the implantation of an intra-corneal ring (INTACS),a ring placed inside the corneal tissue. This may help slow disease progression to some extent. Another alternative is corneal transplantation surgery.
Corneal transplantation is usually considered the last option, due to the shortage of corneal donors, high costs, and the risk of graft rejection (about 15–20%). In recent years, however, an effective treatment called Corneal Cross-Linking has been developed, which can halt disease progression and is successfully applied in many centers.
The exact cause is unknown. In some cases, it appears to be genetic, as it is present in about 1 in 10 patients’ parents. Eye allergies, frequent vigorous eye rubbing, and connective tissue disorders such as Ehlers-Danlos syndrome or Marfan syndrome have also been linked to keratoconus.
Keratoconus usually begins in the late teens or early 20s. Vision gradually worsens over 10–20 years. It typically affects both eyes, though progression may differ between them.
Early symptoms include:
As the disease progresses, symptoms worsen:
Although keratoconus usually progresses slowly, in some cases it can advance rapidly. Corneal swelling and scarring may develop, reducing corneal transparency and causing faster deterioration of vision.
Keratoconus can be detected during a routine eye examination. If suspected, the doctor evaluates the curvature of the cornea and confirms the diagnosis using computerized imaging devices that generate a detailed corneal map (corneal topography).
Treatment varies depending on the stage of the disease and the severity of symptoms. In the early stages, eyeglasses may suffice, while in progressive cases rigid contact lenses are often required to improve vision. Intra-corneal ring implants (INTACS) can help flatten the cornea and improve vision.
Corneal Cross-Linking (CXL) strengthens collagen fibers in the cornea, helping to stop thinning and bulging. When all other options are exhausted, corneal transplantation is performed, replacing the damaged cornea with healthy donor tissue.
Patients with keratoconus should avoid rubbing their eyes, as vigorous rubbing can accelerate disease progression and worsen symptoms. If you have itchy eyes, consult your doctor for appropriate preventive measures.
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