Keratoconus

What is Keratoconus?

Keratoconus is a condition where the cornea, the clear front surface of the eye, gradually becomes thinner and bulges forward into a cone-like shape. This change alters how light enters the eye, leading to blurred or distorted vision, increased short-sightedness and astigmatism, and frequent changes in glasses or contact lens prescriptions.

It usually begins in the teenage years or early adulthood and can progress over time. Early keratoconus may be managed with glasses or contact lenses, while more advanced cases may require specialised contact lenses, corneal cross-linking to slow progression, or other surgical treatments to improve vision and maintain corneal stability.

What are the risk factors for keratoconus?

Family history of keratoconus or corneal thinning disorders
Frequent or vigorous eye rubbing
Allergic eye disease (hay fever, allergic conjunctivitis, eczema)
Genetic or connective tissue conditions (e.g. Down syndrome, Marfan syndrome, Ehlers–Danlos syndrome)
Chronic eye irritation or inflammation
Poorly controlled atopy or asthma
Onset during adolescence or early adulthood

What are the signs and symptoms of keratoconus?

Common symptoms include blurry or fluctuating vision, increasing astigmatism, glare or halos at night, and frequent changes in glasses or contact lens prescriptions. The refractive error (mainly shortsightedness and astigmatism) can initially be correctable with glasses. At later (advanced) stages, glasses can no longer effectively correct your sight.

Experience how keratoconus affects your sight

How is keratoconus diagnosis?

Keratoconus is diagnosed through a detailed eye examination combined with specialised corneal imaging. Key tests include corneal topography or tomography, which create colour maps showing abnormal steepening and thinning of the cornea. Subtle changes can be detected even before vision is significantly affected, making these scans essential for early diagnosis and monitoring progression

What is the treatment for keratoconus?

Treatment for keratoconus depends on severity and whether the condition is progressing.
In early stages, vision can often be managed with glasses or soft contact lenses, though these may become less effective as the cornea becomes more irregular.

As the condition progresses, specialty contact lenses are commonly used:

Rigid Gas Permeable (RGP) lenses: provide clearer vision by masking corneal irregularity
Scleral lenses: larger lenses that vault over the cornea and rest on the white of the eye, offering excellent comfort and vision in more advanced disease

To stop progression, corneal cross-linking is the key treatment. This procedure strengthens the cornea using riboflavin (vitamin B2) and ultraviolet light, helping to halt further thinning and bulging.

In severe or advanced cases, where vision can no longer be adequately corrected with glasses or contact lenses, corneal transplantation may be required. Options include PKP (full-thickness corneal transplant) or DALK (partial-thickness transplant), depending on the depth of corneal involvement.

Cross-Linking

What is corneal cross-linking?
Corneal cross-linking is a procedure designed to strengthen the cornea and stop progression of keratoconus (or other corneal ectasia). It does not reverse the cone shape, but it helps stabilise the cornea and preserve existing vision.

What does the procedure involve?
The eye is numbed with drops, and riboflavin (vitamin B2) drops are applied to the cornea, followed by controlled ultraviolet (UV) light exposure. This creates new chemical bonds (“cross-links”) within the corneal collagen, making the cornea stiffer and more resistant to further thinning. The procedure is usually performed as a day case.

Indications for cross-linking
Cross-linking is recommended when keratoconus is progressive, particularly in younger patients, or when scans show worsening corneal steepening or thinning over time. The goal is to prevent further deterioration, not to improve vision directly.

What to expect after the procedure
The eye is typically sore or gritty for a few days, with light sensitivity and blurred vision during early healing. Vision may fluctuate for several weeks and can take weeks to months to stabilise. Most patients return to normal activities within a few days, and long-term, the cornea usually remains stable, reducing the risk of needing more invasive surgery later.

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