Keratoconus is a non-inflammatory, degenerative disorder of the cornea, the transparent front surface of the eye responsible for focusing light. In this condition, the cornea gradually becomes thinner and weaker, causing it to bulge outward into a cone-like shape.
A healthy cornea has a smooth, dome-shaped curvature. In keratoconus, the irregular cone shape prevents light from focusing properly on the retina, resulting in distorted and blurred vision that cannot be fully corrected with regular glasses.
The disease often affects both eyes, though one eye may progress faster or be more severely affected than the other.
Who Is Affected by Keratoconus?
Keratoconus typically begins during teenage years or early adulthood, often between the ages of 10 and 25. The condition may progress slowly over 10–20 years before stabilizing.
Risk Factors Include:
- Family history of keratoconus
- Chronic eye rubbing
- Allergic eye disease (e.g., vernal keratoconjunctivitis)
- Connective tissue disorders
- Poorly fitted contact lenses
Early onset often correlates with faster and more severe progression, making early diagnosis critical.
What Causes Keratoconus?
The exact cause of keratoconus remains unclear, but it is widely accepted to be multifactorial, involving genetic, biochemical, and environmental influences.
Key Contributing Factors
1. Genetic Predisposition
Studies suggest that keratoconus can run in families, indicating a genetic component. However, it does not follow a simple inheritance pattern.
2. Corneal Weakening
In keratoconus, the collagen fibers that give the cornea its strength become disorganized and weak, making the cornea unable to maintain its normal shape.
3. Oxidative Stress
Reduced antioxidant activity in the cornea may lead to tissue damage and thinning over time.
4. Chronic Eye Rubbing
Persistent eye rubbing—often associated with allergies—has been strongly linked to disease progression and worsening corneal deformation.
Signs and Symptoms of Keratoconus
Keratoconus symptoms vary depending on the stage of the disease and may worsen gradually.
Early Symptoms
- Blurred or distorted vision
- Frequent changes in glasses or contact lens prescriptions
- Increased sensitivity to light
- Eye strain and headaches
Progressive Symptoms
- Ghosting or double vision (especially in one eye)
- Halos and glare around lights
- Poor night vision
- Difficulty reading or driving
Advanced Symptoms
- Sudden vision loss due to corneal swelling (acute hydrops)
- Severe visual distortion
- Reduced tolerance to contact lenses
Because early symptoms resemble simple refractive errors, keratoconus is often missed in its initial stages.
How Is Keratoconus Diagnosed?
Early and accurate diagnosis is essential to prevent irreversible vision loss.
Comprehensive Eye Examination
An eye care specialist will evaluate:
- Visual acuity
- Refraction changes
- Corneal thickness
Corneal Topography (Gold Standard)
Corneal topography creates a detailed curvature map of the cornea, detecting even subtle irregularities before symptoms become obvious.
Corneal Tomography
Advanced imaging techniques measure both the front and back surfaces of the cornea, allowing earlier detection of disease progression.
Stages of Keratoconus
Keratoconus is often categorized into stages based on severity:
- Mild – Slight corneal thinning, vision correctable with glasses
- Moderate – Increased irregularity, requires specialty contact lenses
- Advanced – Severe thinning and scarring, limited correction options
- Severe – Corneal transplantation may be required
Progression rates differ significantly between individuals.
Treatment Options for Keratoconus
While keratoconus cannot be cured, modern treatments can slow progression and significantly improve vision.
1. Glasses and Soft Contact Lenses
In early stages, mild irregular astigmatism can be corrected with glasses or soft lenses. However, as the cornea becomes more irregular, these options become less effective.
2. Rigid Gas Permeable (RGP) Contact Lenses
RGP lenses create a smooth optical surface over the irregular cornea, improving visual clarity. They do not stop disease progression but significantly enhance vision.
3. Scleral and Hybrid Lenses
- Scleral lenses vault over the cornea and rest on the sclera, offering superior comfort and vision
- Hybrid lenses combine a rigid center with a soft outer ring
These are often the best option for moderate to advanced keratoconus.
4. Corneal Collagen Cross-Linking (CXL)
Corneal cross-linking is the only treatment proven to halt or slow keratoconus progression.
How It Works:
- Riboflavin (vitamin B2) drops are applied to the cornea
- Ultraviolet light activates collagen strengthening
- Increases corneal rigidity
CXL is most effective when performed early, before severe thinning occurs.
5. Intracorneal Ring Segments (ICRS)
Small, crescent-shaped plastic rings are implanted into the cornea to:
- Flatten the cornea
- Improve shape symmetry
- Enhance contact lens tolerance
ICRS do not stop progression but can improve vision in selected cases.
6. Corneal Transplantation (Keratoplasty)
In advanced cases with scarring or extreme thinning, surgery may be required.
Types of Transplant:
- Deep Anterior Lamellar Keratoplasty (DALK) – preserves inner corneal layers
- Penetrating Keratoplasty (PK) – full-thickness transplant
Most patients achieve significant vision improvement post-surgery, though recovery can take months.
Living With Keratoconus
A diagnosis of keratoconus can be emotionally challenging, especially for young patients. However, with proper management, most individuals maintain functional vision and lead normal lives.
Practical Tips:
- Avoid eye rubbing
- Manage allergies proactively
- Attend regular follow-ups
- Use prescribed lenses consistently
- Seek early intervention for progression
Keratoconus and Quality of Life
Untreated keratoconus can affect education, career choices, and daily activities such as driving. Early detection and timely treatment can dramatically reduce these impacts and preserve independence.
Advancements in imaging, contact lens design, and corneal procedures have transformed keratoconus from a disabling disease into a manageable chronic condition.
Final Thoughts
Keratoconus is a progressive corneal disease that requires early diagnosis, individualized treatment, and long-term monitoring. Awareness of symptoms and access to modern eye care can prevent severe vision loss and the need for invasive surgery. If you or someone you know experiences frequent prescription changes, distorted vision, or poor night vision at a young age, a comprehensive corneal evaluation is essential.
