Keratoconus
Also known as: Conical cornea, KC
Keratoconus is a progressive eye condition in which the cornea, the clear dome-shaped window at the front of the eye, gradually thins and bulges outward into a cone shape. This distorts the way light enters the eye, causing blurred and distorted vision, increasing nearsightedness and irregular astigmatism, and sensitivity to light and glare. It typically begins in the teens or twenties, affects both eyes (often unevenly), and progresses over 10 to 20 years before stabilizing. Keratoconus cannot be corrected well with ordinary glasses once it advances, but specialized contact lenses restore good vision for most people, and corneal cross-linking can halt progression if caught early. Corneal transplant is needed only in a minority of advanced cases.
At a Glance
- Common symptoms
- Gradually worsening blurred or distorted vision, Frequent changes in glasses prescription, especially increasing astigmatism, Increased sensitivity to light and glare, particularly at night
- Main treatments
- Glasses or soft contact lenses in the early stages, Rigid gas-permeable, hybrid, or scleral contact lenses to create a smooth optical surface in moderate to advanced disease, Corneal collagen cross-linking (using riboflavin and UV light) to strengthen the cornea and stop progression
- Category
- Eye & Ear · Uncommon; usually begins in adolescence or early adulthood and affects all ethnic groups
- See a doctor if
- Vision that keeps getting worse despite new glasses
Symptoms
Causes
- Weakening of the collagen fibers that give the cornea its structure; the exact cause is unknown
- Genetic predisposition, with a family history in a notable minority of cases
- Chronic eye rubbing, which is strongly associated with onset and progression
- Oxidative stress and imbalance of enzymes in the cornea
- Association with allergic eye disease and conditions such as Down syndrome and connective tissue disorders
Risk Factors
- Family history of keratoconus
- Vigorous or habitual eye rubbing
- Allergic conditions such as hay fever, eczema, and asthma
- Down syndrome, Ehlers-Danlos syndrome, or Marfan syndrome
- Adolescence and young adulthood at onset
Diagnosis
- Eye examination with refraction showing irregular astigmatism
- Slit-lamp examination of the cornea for thinning and characteristic signs
- Corneal topography or tomography, which maps the shape and thickness of the cornea and detects early disease
- Pachymetry to measure corneal thickness
- Regular repeat mapping to monitor for progression
Treatment
- Glasses or soft contact lenses in the early stages
- Rigid gas-permeable, hybrid, or scleral contact lenses to create a smooth optical surface in moderate to advanced disease
- Corneal collagen cross-linking (using riboflavin and UV light) to strengthen the cornea and stop progression
- Intracorneal ring segments to flatten the cornea and improve lens fit in some cases
- Corneal transplant (partial or full thickness) for advanced disease with scarring or intolerance of lenses
- Supportive: stopping eye rubbing, which is the single most important self-care measure
- Supportive: treating allergic eye symptoms with antihistamine drops to reduce the urge to rub
Prevention
- Do not rub your eyes; use cold compresses or lubricating drops for itch instead
- Treat eye allergies promptly
- Have regular eye examinations, especially if there is a family history
- Have children and siblings of affected people screened with corneal mapping
- Follow up as advised so cross-linking can be offered at the first sign of progression
When to See a Doctor
- Vision that keeps getting worse despite new glasses
- Increasing distortion, ghosting, or glare, especially in a young person
- A sudden drop in vision, pain, or a cloudy cornea (may be acute hydrops)
- Contact lenses that have become uncomfortable or no longer give clear vision
- A family history of keratoconus with any change in vision
Frequently Asked Questions
Related Conditions
Have questions about Keratoconus?
Ask Mother Nature AI for personalized, evidence-based guidance.
Ask about KeratoconusMedical Disclaimer: This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.
Content reviewed against peer-reviewed medical literature and clinical guidelines. Read our editorial standards.