Keratoconus

Keratoconus is a progressive eye condition in which the normally round cornea thins and bulges outward into a cone-like shape. This irregular shape prevents light from focusing correctly on the retina, causing distorted and blurry vision that glasses alone often cannot fully correct.

Overview

Keratoconus affects roughly 1 in 2,000 people, though recent studies suggest it may be more common. The condition typically starts during puberty and progresses through the 20s and 30s before stabilizing. Early detection is important because corneal cross-linking can stop the disease from getting worse.

Stages of Keratoconus

Stage	Corneal Changes	Vision	Treatment
Mild	Slight thinning, mild steepening	Correctable with glasses or soft contacts	Monitor; cross-linking if progressing
Moderate	Noticeable cone, thinning on pachymetry	Requires rigid or scleral lenses	Cross-linking to halt; specialty lenses
Advanced	Significant cone, possible scarring	Poor even with lenses	May need corneal transplant
Hydrops	Acute rupture of Descemet's membrane	Sudden clouding, pain	Emergency management; eventual transplant

Causes and Risk Factors

What Causes Keratoconus

The exact cause is not fully understood, but it involves a combination of genetic susceptibility and environmental triggers that weaken the structural proteins (collagen) in the cornea.

Key Risk Factors

• Eye rubbing—the single most important modifiable risk factor
• Family history—first-degree relatives have 15-67× increased risk
• Atopy (allergies, eczema, asthma)—itchy eyes lead to rubbing
• Down syndrome—significantly higher prevalence
• Connective tissue disorders (Ehlers-Danlos, Marfan syndrome)
• Sleep position—sleeping face-down may contribute

Symptoms

• Blurred or distorted vision that worsens over time
• Increasing astigmatism with frequent prescription changes
• Ghost images or multiple images from a single object
• Glare and halos around lights, especially at night
• Difficulty with night driving
• Light sensitivity
• Eye strain and headaches

Diagnosis

Key Tests

• Corneal topography—the gold standard for detecting and monitoring keratoconus; maps the curvature of the cornea and reveals the characteristic cone pattern
• Pachymetry—measures corneal thickness, which is reduced in keratoconus
• Slit-lamp exam—may reveal Vogt striae, Fleischer ring, or corneal scarring
• Corneal tomography (Pentacam/Orbscan)—provides front and back surface maps along with thickness profiles

Early Detection

Topographic changes can be detected before symptoms appear, which is why screening is recommended for:

• Family members of keratoconus patients
• Patients with progressive or irregular astigmatism
• Anyone considering refractive surgery (LASIK is contraindicated in keratoconus)

Treatment

Corneal Cross-Linking (CXL)

The only treatment that halts keratoconus progression:

• Riboflavin (vitamin B2) drops are applied to the cornea
• UV-A light activates the riboflavin
• Creates new collagen bonds that stiffen the cornea
• Outpatient procedure taking about 60-90 minutes
• Most effective when done early, before significant damage

Vision Correction

Glasses and soft contacts — adequate for mild cases only

Rigid gas-permeable (RGP) lenses — provide better vision by creating a smooth optical surface over the irregular cornea

Scleral lenses — large-diameter lenses that vault over the entire cornea:

• Rest on the white of the eye (sclera)
• Very comfortable despite their size
• Provide excellent vision
• Hold a fluid reservoir that keeps the cornea hydrated
• The preferred lens option for most moderate-to-advanced cases

Hybrid lenses — rigid center with soft skirt for comfort

Piggyback lenses — soft lens underneath with RGP on top

Intrastromal Corneal Ring Segments (Intacs)

• Small plastic inserts placed within the cornea
• Flatten the cone to improve shape
• May improve contact lens fit
• Less commonly used since cross-linking became available

Corneal Transplant

For severe keratoconus that cannot be managed with lenses:

• Penetrating keratoplasty (PK)—full-thickness transplant
• Deep anterior lamellar keratoplasty (DALK)—partial-thickness, preserves patient's endothelium (lower rejection risk)
• High success rate (>90% graft survival at 10 years)
• Recovery takes months; sutures remain for 1+ year
• Glasses or contact lenses still usually needed after transplant

When to See a Doctor

Frequently Asked Questions

Can keratoconus be cured?

Keratoconus cannot be cured, but it can be effectively managed. Corneal cross-linking can stop progression, and specialty contact lenses can restore excellent functional vision for most patients.

Will I go blind from keratoconus?

Keratoconus very rarely causes total blindness. Even in advanced cases, corneal transplant surgery has a high success rate. With modern treatments including cross-linking and scleral lenses, most patients maintain good functional vision.

Can I have LASIK if I have keratoconus?

No. LASIK and other corneal refractive surgeries that thin the cornea are contraindicated in keratoconus. These procedures can worsen the condition. This is why corneal topography screening is done before LASIK.

Does keratoconus affect both eyes?

Yes, keratoconus is bilateral in about 96% of cases, though one eye is usually more advanced than the other. If diagnosed in one eye, the other should be monitored closely.

At what age does keratoconus stop progressing?

Keratoconus typically stabilizes by the late 30s to 40s, but there is no guaranteed age. Cross-linking is recommended for progressive cases rather than waiting for natural stabilization.

References