Keratoconus Treatment

Why the cornea becomes cone-shaped

The cornea is the clear, dome-shaped window at the front of the eye and the first surface to bend incoming light. In keratoconus its tissue weakens, so the cornea thins and bulges forward into a cone. Because the surface is no longer smooth, light cannot focus properly on the retina, and images look blurred, wavy, shadowed or distorted.

Both eyes are usually affected, although one is often further along than the other. A family history of keratoconus, allergic eye disease and frequent eye rubbing all raise the risk.

Signs to watch for in teenagers

Keratoconus usually begins around puberty and can progress through the teens and twenties. The earlier it starts, the faster it tends to progress, which is why children and teenagers are followed up more closely.

• Blurred, wavy vision
• Glasses that never quite give sharp vision
• A prescription that keeps changing, particularly the astigmatism
• Light sensitivity, with halos and shadows around lights at night
• Frequent eye rubbing

A teenager whose prescription changes at every visit, or who never sees clearly with glasses, should have their cornea checked with topography.

Why stopping eye rubbing comes first

Frequent, hard rubbing puts mechanical stress on a cornea that is already weak and contributes to progression. Itching is often caused by allergy, and once the allergy is controlled with drops, the urge to rub fades too. When the itch comes, a cold compress over closed lids helps more than rubbing. This rule applies at every stage of treatment.

How keratoconus is diagnosed and monitored

Early keratoconus can go unnoticed at a routine glasses check. The key test is corneal topography (tomography), which maps the curvature of the front and back of the cornea and its thickness at every point. These maps show where the cone is, how steep it is and where the cornea is thinnest.

At follow-up visits the same scan is repeated and the maps are compared to see whether the cornea has become steeper or thinner. If it is progressing, cross-linking is considered. How often you are seen depends on your age and how quickly the disease is changing.

This is also one reason why topography is part of every assessment for laser eye surgery. Laser treatments that thin the cornea are generally not performed on a keratoconic or borderline cornea, because they can accelerate the disease.

Treatment step by step

Treatment has two goals: to stop the disease progressing and to restore useful vision. Which step suits you depends on the stage, how thick the cornea is and whether it is still changing, and many people need more than one method. Assoc. Prof. Dr. Elif Ceren Yeşilkaya plans the sequence with you at the examination, based on your scans and your age.

Glasses and contact lenses

Glasses may be enough in the early stages. As the cornea becomes more irregular, glasses stop giving clear vision and contact lenses take over. A rigid gas permeable lens creates a smooth new optical surface in front of the uneven cornea, with tears filling the gap between the two. Scleral lenses are larger; they vault over the cornea without touching it, rest on the white of the eye (the sclera) and hold a reservoir of fluid underneath. They can be more comfortable in advanced cases or for people who cannot tolerate rigid lenses.

Lenses improve vision but do not stop the disease from progressing. Fitting and trial lenses are covered on the contact lens fitting page.

Corneal cross-linking (CXL)

Cross-linking is the treatment used to halt progression. Riboflavin (vitamin B2) drops are soaked into the cornea, which is then exposed to a controlled dose of ultraviolet A light. Together, the light and riboflavin create new bonds between the collagen fibres of the cornea. The cornea becomes stiffer, and the cone stops steepening or slows down.

In the standard method the thin outer layer of the cornea (the epithelium) is removed, so the early days bring pain, grittiness, watering and blurred vision. A protective contact lens stays in place until the surface heals. The cornea stiffens gradually, and vision settles over time. Follow-up topography confirms whether progression has stopped.

CXL does not reverse the existing cone, and you may still need glasses or contact lenses afterwards. If the cornea is very thin, the standard method may not be possible; thickness measurements show this.

Corneal ring segments

At a moderate stage, if contact lenses do not give adequate vision or cannot be worn, thin, clear plastic crescent-shaped segments can be placed inside the cornea. They sit in a tunnel made in the corneal tissue, either with a laser or mechanically, and flatten the central part of the cone so the surface becomes more regular. They can be removed if necessary.

How quickly vision improves varies from person to person and is discussed at your examination. Rings do not stop progression, so if the disease is still advancing they are planned together with CXL.

Phakic intraocular lens (ICL)

If the cornea is stable but a high degree of short-sightedness or astigmatism remains, a thin lens can be placed inside the eye without removing your natural lens. The procedure is described on the phakic intraocular lens (ICL) page.

Advanced stage: corneal transplant

A corneal transplant may be needed if the cornea has become very thin, if a scar has formed in its centre, or if no contact lens gives adequate vision. In keratoconus the inner layer of the cornea (the endothelium) is usually healthy, so a transplant that replaces only the front layers, called DALK, is often preferred; a full-thickness transplant is done if needed. Recovery happens in stages, with stitches removed and vision checked at follow-up visits.

When keratoconus needs urgent attention

In advanced keratoconus the inner membrane of the cornea can tear. The cornea takes up fluid and suddenly turns white, vision drops sharply, and pain, watering and light sensitivity follow. This is called acute hydrops and needs to be seen promptly. In the days after CXL, pain that increases instead of easing, discharge or worsening vision can signal infection. In any of these situations, do not wait for your next appointment; seek help without delay.

Keratoconus follow-up and treatment take place at Medicana Zincirlikuyu (Şişli, Istanbul). At the first visit your corneal topography and corneal thickness are measured. If you wear contact lenses, they can temporarily alter the shape of the cornea and affect the scan, so ask how many days beforehand to stop wearing them when you book.