In keratoconus the cornea gradually becomes thinner and bulges into a cone shape. This distorts the image and can often be only partly corrected with glasses alone. The encouraging part: caught early, the course can in many cases be stabilised, and for vision there are several options today. What matters is acting early and taking one avoidable factor seriously: eye rubbing.
The cornea is the clear, dome-shaped front of the eye and focuses the incoming light. You can picture it as a dome carried by a fine scaffold. In keratoconus the stabilising cross-bracing of this scaffold is too weak, the dome loses its support, gives way and bulges into a cone at one point. Usually both eyes are affected, often to differing degrees, and the condition often begins in adolescence or early adulthood.
An unstable, irregular dome can no longer focus light to a single point, the image looks distorted and blurred, often with shadows or double contours. Because glasses assume a regular cornea, beyond a certain point the blur can no longer be corrected with spectacle lenses; rigid (gas-permeable) contact lenses, which give the cornea a smooth front surface, manage this better. The condition can progress over years before settling on its own in many cases.
Vigorous or frequent eye rubbing is regarded as one of the most important risk factors for a keratoconus starting or progressing: the mechanical pressure places additional strain on an already weakened cornea. Often itching is behind it, for example with allergies or dry eyes. So the rule is consistent: don't rub, and have the cause of the itching treated. This is the one point you actively have in your own hands, and it can help decide the further course.
The earlier a keratoconus is detected, the sooner its progression can be halted before vision suffers permanently. It becomes visible above all in corneal measurement (topography and tomography), which precisely maps the shape and thickness of the cornea, often before symptoms appear. A frequently changing spectacle prescription, especially in younger people, should raise attention. The precise measurement of the cornea and the eye is at the same time a focus of my scientific work.
Treatment pursues two different goals that should be kept apart: first, to stop progression (stabilise the cornea); second, to improve vision (compensate for the irregular shape). Which procedures come into question depends on the stage, the corneal thickness and your symptoms, the examination clarifies this.
Cross-linking (corneal collagen cross-linking) is the central procedure for halting progression, it acts precisely on the weak scaffold. Using vitamin B2 (riboflavin) and UV-A light, additional cross-connections are created within the corneal tissue: in effect the missing cross-bracing that stiffens the dome again. The aim is stabilisation, cross-linking is meant to stop the course, but does not usually reverse an existing deformation and is therefore not a procedure for improving vision as such.
In suitable cases a gentle laser ablation tailored to the corneal shape (PRK) can be combined with cross-linking: the laser smooths the irregular surface, the cross-linking stabilises it. The aim is, alongside stabilisation, to also improve visual quality. Because tissue is removed, this path only comes into question with sufficient corneal thickness and in selected situations, suitability is carefully assessed.
CAIRS (Corneal Allogenic Intrastromal Ring Segments) is a newer procedure in which fine ring segments of human donor corneal tissue are placed into the cornea to regularise the cone-shaped protrusion and improve vision. Unlike classic plastic rings, tissue similar to the body's own is used. Depending on the findings, CAIRS can be combined with cross-linking.
For correcting vision alone, glasses and above all rigid or scleral contact lenses are in many cases the first choice, they compensate for the irregular cornea optically, without any procedure. They do not, however, stabilise the condition; documented progression is treated independently of them.
If the keratoconus is stable, it is often only a matter of compensating for the remaining refractive error and becoming more independent of glasses. Here a phakic lens (such as an ICL) can help: an additional lens placed inside the eye while your own lens is preserved. It does not change the cornea but corrects the prescription, an option above all in stable courses, and depending on the findings also in combination with the stabilising procedures. On phakic lenses in keratoconus I have co-published clinical results (Graefes Arch Clin Exp Ophthalmol, 2021).
If a cataract develops over the years, its surgery is considerably more demanding in keratoconus than in a normal eye: the irregular cornea complicates both the calculation of the artificial lens and the choice of lens type. Considerations include whether a spherical, an aberration-neutral or an aberration-correcting lens makes sense, whether a toric lens to offset the astigmatism comes into question, and whether additional procedures should improve the optics beforehand. This is exactly where my two research fields intersect: the calculation of artificial lenses and keratoconus. That allows a well-founded assessment tailored to your eye.
In advanced cases, with scarring, a very thin cornea or when contact lenses are no longer tolerated, a partial (DALK) or full-thickness (PKP) corneal transplant may become necessary. This is exactly what the procedures above aim to prevent: caught early and stabilised, a transplant can often be avoided or postponed for a long time.
Keratoconus is one of my scientific focuses. I have published on the biomechanics of the cornea and on cross-linking (J Refract Surg, 2021; Curr Eye Res, 2023), on the precise determination of corneal power in keratoconus (Clin Exp Ophthalmol, 2026) and on the influence of epithelial changes on corneal and lens calculation in irregular corneas (Ophthalmic Physiol Opt, 2025; Z Med Phys, 2025). An overview is available on PubMed.
Added to this is the selection and calculation of lenses, from phakic lenses such as the ICL (more on my ICL page) to the artificial lens in cataract surgery. On lens choice and calculation in keratoconus specifically, I have lectured at numerous congresses and meetings. This lets me judge first-hand what the procedures can do and where their limits lie, rather than from a brochure.
Whether and how to treat depends on the stage, the cornea and your symptoms. In consultation we measure the cornea, classify the findings honestly and discuss which path, stabilise, improve vision, or observe for now, makes sense for you.
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