What Is Keratoconus and Can It Be Treated?

Short answer: Keratoconus is a progressive condition in which the cornea thins and takes on a cone-like shape, causing progressive irregular astigmatism and blurry vision that glasses cannot fully correct. It can be treated — corneal cross-linking halts progression, and scleral lenses or corneal transplant can restore functional vision. It disqualifies patients from LASIK and most laser vision correction.

This is a condition with direct surgical implications covered in the Eye Health and Vision Care resource. Here is what patients and prospective surgical candidates need to know.

What Keratoconus Does to the Cornea

The cornea is normally shaped like a sphere — a smooth, regular dome. In keratoconus, the structural proteins (collagen) of the cornea weaken, causing the central or inferior cornea to bulge forward in an irregular, cone-like shape. This irregular shape scatters light rather than focusing it cleanly, producing distorted, blurry vision that cannot be corrected with standard spherical or cylindrical lenses.

Keratoconus typically begins in adolescence or early adulthood. It is bilateral (affects both eyes) in most cases, though one eye is usually more advanced. It progresses at varying rates — rapidly in some patients through their twenties, slowly or imperceptibly in others. Progression typically slows or stops by the mid-thirties to forties.

Symptoms

Progressive blurring of vision not adequately corrected by glasses
Ghost images or monocular diplopia (seeing a “ghost” around objects with one eye)
Light sensitivity and glare, especially at night
Frequent prescription changes that do not stabilize
Halos around lights
Increased irregular astigmatism noted on refraction

The challenge with early keratoconus is that symptoms can be subtle and may initially be attributed to garden-variety astigmatism. Frequent, unexplained prescription changes with increasing irregular astigmatism should prompt corneal topographic evaluation.

Diagnosis

Keratoconus cannot be adequately screened with a standard visual acuity test or simple autorefraction. Diagnosis requires:

Corneal topography: Maps the curvature of the anterior corneal surface and detects asymmetric or inferiorly steepened patterns characteristic of keratoconus.

Corneal tomography (Scheimpflug imaging): Maps both the anterior and posterior corneal surfaces and provides thickness maps. Posterior corneal elevation changes are often the earliest detectable sign of subclinical keratoconus — visible before topography shows obvious changes.

Forme fruste keratoconus — the early subclinical form — can only be reliably detected with tomographic screening. This is why advanced imaging is a non-negotiable part of any LASIK pre-operative evaluation in a high-quality practice. See corneal health and vision correction for the full discussion.

Treatment Options

1. Corneal cross-linking (CXL): The only treatment that halts progression. Riboflavin (vitamin B2) drops are applied to the cornea and activated with UV light, creating additional collagen cross-links that stiffen and strengthen the corneal structure. FDA-approved since 2016. Most effective when performed early, before significant curvature change has occurred. Does not restore the cornea to normal shape — it stops further deterioration.

2. Rigid gas-permeable (RGP) contact lenses: Custom-fitted rigid lenses create a smooth tear lens over the irregular cornea, producing good optical correction that glasses cannot achieve. A primary management tool for mild to moderate keratoconus.

3. Scleral contact lenses: Large-diameter rigid lenses that vault over the entire corneal surface and rest on the less sensitive sclera (white of the eye). Provide excellent vision correction and comfort for moderate to advanced keratoconus. Increasingly the preferred lens modality for significant keratoconus.

4. Corneal transplant (penetrating keratoplasty or DALK): For advanced keratoconus not manageable with contact lenses. Deep anterior lamellar keratoplasty (DALK) preserves the patient’s endothelium, which reduces the risk of rejection compared to full-thickness transplants. Recovery from corneal transplant is extended (often one to two years before stable vision is achieved).

Keratoconus and LASIK: Absolute Contraindication

Keratoconus — including suspected or forme fruste keratoconus — is a contraindication to LASIK and most corneal refractive laser procedures. Performing LASIK on a keratoconic cornea risks accelerating the ectatic process and causing progressive post-operative vision loss that may require corneal transplant to manage.

EVO ICL is a viable option for some keratoconus patients who want improved spectacle independence, as it does not alter the corneal surface. ICL correction can be combined with corneal cross-linking in appropriate patients.