Keratoconus

Treating
keratoconus

There is no single treatment for keratoconus, but answers to two distinct questions: is the disease changing, and is your vision sufficient. These two questions call for neither the same means nor the same timing, and they may perfectly well receive opposite answers in the same patient. This is why the approach always begins with the indication, never with the technique.

Two objectives not to be confused

Stabilising the cornea and correcting vision are two distinct objectives. The first aims to prevent the distortion from worsening; the second aims to obtain the best possible vision with the cornea as it is today. An intervention that stabilises does not improve vision. And a correction that improves vision does not necessarily stop the disease from progressing.

This distinction is not theoretical. It explains why a patient whose vision is comfortable may be offered surgery, and why a patient who is greatly troubled is, on the contrary, often offered a contact lens fitting first.

Doing nothing is an option

Keratoconus that is not changing, in a patient whose corrected vision is satisfactory, warrants no intervention. Monitoring alone is then a medical decision in its own right, not an absence of decision.

This situation is common, particularly in adults whose diagnosis is long-standing.

Progression and monitoring →

The decision logic

The two questions intersect and describe four situations. The table below sets out a logic, not a protocol: each cell is assessed in the light of your age, your daily activities, your visual needs and the state of both eyes.

Corrected vision satisfactory Corrected vision insufficient
No documented progression Monitoring alone Improve the optical correction, then consider reshaping the cornea if needed
Documented progression Stabilise the cornea; the correction remains unchanged Stabilise first, reassess the correction afterwards
Decision logic for keratoconus: two independent questions, four situations A two-by-two table. The columns distinguish satisfactory from insufficient corrected vision; the rows distinguish the absence of documented progression from documented progression. Each of the four cells states the resulting course of action, from monitoring alone to stabilising the cornea before correcting it. DECISION LOGIC Two independent questions. Four situations. CORRECTED VISION SATISFACTORY CORRECTED VISION INSUFFICIENT NO DOCUMENTED PROGRESSION DOCUMENTED PROGRESSION Monitoring alone No intervention warranted Improve the correction then reshape the cornea if needed Stabilise the cornea the correction remains unchanged Stabilise, then correct in that order Order matters: on a cornea still changing, correction waits. Schematic. Each situation is assessed individually; this describes a logic, not a protocol.

Order matters. When both questions arise at the same time, stabilisation generally precedes correction: there is little point in finely fitting a correction on a cornea whose shape is still changing.

Optical correction comes first

In the great majority of situations, vision is corrected without surgery.

Glasses suit early forms, as long as the astigmatism remains reasonably regular. They cease to be sufficient when the distortion becomes too irregular: this is not a fitting failure, but a physical limit of correction by spectacle lenses.

Rigid gas-permeable lenses are the main answer to irregular astigmatism. The principle is simple: the lens, being undeformable, creates a new regular surface, and the tear film fills the space between it and the cornea. Light is focused correctly again, even though the cornea itself has not changed.

Scleral lenses rest on the sclera — the white of the eye — and vault over the cornea without pressing on it. They are useful when the cornea is too distorted for a conventional rigid lens to stay in place, or when tolerance is insufficient.

Fitting rigid and scleral lenses is specialised, iterative work: several trials are usual before reaching a satisfactory balance between vision, comfort and tolerance across the day. A disappointing first trial does not predict the final result. Some opticians highly skilled in this discipline lead this part of the care.

Lenses do not modify the course of the disease. They correct vision, they do not stabilise the cornea — and tolerating them well therefore does not dispense with monitoring.

Keratoconus →

When the disease progresses: stabilising

When progression is documented by examinations compared over time, the question becomes how to halt it. That is the objective of corneal cross-linking, an intervention that aims to reinforce the mechanical cohesion of the cornea.

It does not correct vision and replaces no optical correction: its purpose is to prevent worsening. The conditions to be met, the procedure and its limits are detailed on its own page.

Corneal cross-linking →

When optical correction is no longer enough: reshaping

When lenses are no longer tolerated, or no longer allow sufficient vision, another route is to act on the shape of the cornea itself. Intracorneal segments — thin segments placed within the thickness of the cornea — aim to regularise its curvature, so that a correction becomes possible again. These segments were formerly synthetic (ICRS) and are now increasingly biological (CAIRS).

They have no demonstrated stabilising effect: they address vision, not the course of the disease. They may be combined with stabilisation when both questions arise together.

Intracorneal segments →

In selected cases, topography-guided photoablation — a surface laser treatment, set according to the map of your cornea — may also be offered to improve the regularity of the surface. The intention here is therapeutic and not refractive: it is a matter of smoothing an irregular surface, not of removing a correction. This procedure presupposes sufficient corneal thickness and a stabilised disease, and it is usually combined with cross-linking if that has not already taken place.

Irregular corneas and opacities →

Advanced situations

When the cornea has become too thin, too distorted or too opaque for a correction or a reshaping to be contemplated, replacing part of the corneal thickness may be discussed. This situation concerns a minority of patients, and all the fewer when the diagnosis was made early and progression monitored.

Keratoconus and refractive surgery

Laser techniques that correct myopia or astigmatism by thinning the cornea — LASIK, KLEx — remain contraindicated, including in stabilised keratoconus.

The laser reshaping of the corneal surface discussed above does not breach this rule.

The distinction lies in the intention, not in the instrument. Removing a correction from a weakened cornea weakens it further; regularising a distorted surface pursues another aim, with a different setting and a far smaller depth of treatment. This is why a topography-guided surface treatment can be discussed where refractive surgery cannot.

In certain patients whose disease is stabilised and whose cornea is fairly regular, correction with a phakic implant may be discussed. This assessment is specific and is never concluded on a single criterion.

The phakic implant →

What decides

None of these options is chosen on an isolated figure. The decision brings together the course documented over time, the vision actually obtained with the best correction, the state of both eyes, your age and your daily needs.

It is reassessed: a decision not to intervene today does not commit the future, and an intervention carried out does not end follow-up.

Coverage and reimbursement →

Frequently asked questions →

An indication to establish, or a decision to compare?

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What monitoring must establish before any decision

Progression and monitoring →
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