Understanding Keratoconus
Keratoconus is a progressive corneal disease in which the cornea gradually thins and deforms, taking on a cone-like shape. This distortion causes increasingly blurry and irregular vision that cannot be fully corrected with conventional glasses. This guide explains what keratoconus is, how it is diagnosed, and the main treatment options available today.
This information is for educational purposes. It does not replace a clinical assessment. Any treatment decision must be based on an individualised ophthalmological evaluation.
What is keratoconus?
The cornea is the transparent front surface of the eye. In a healthy eye it has a smooth, dome-like shape that refracts light evenly onto the retina. In keratoconus, the corneal tissue weakens and loses its structural rigidity, causing it to bulge forward into an irregular cone.
This progressive deformation produces increasing myopia, irregular astigmatism, and visual distortion that worsens over time. The disease typically begins during adolescence or early adulthood and may progress for years before stabilising.
Keratoconus affects approximately 1 in 2,000 people, though recent studies suggest the prevalence may be higher when detected early with modern imaging technology.
Normal eye vs. keratoconus
The cornea has a smooth, dome-like shape. Light is focused correctly onto the retina.
The cornea thins and bulges into a cone. Light is scattered and the image reaches the retina distorted.
How does it present?
Keratoconus often begins subtly. Many patients initially notice a decline in vision that requires frequent changes of glasses prescription.
Blurred or distorted vision, especially at night
Frequent changes in glasses prescription that do not fully correct the problem
Halos, glare, or ghosting around lights
Difficulty with tasks requiring fine visual detail (reading, driving)
Increased sensitivity to light
Eye rubbing habit (a known risk factor for progression)
Eye rubbing is strongly associated with keratoconus progression. If you have been diagnosed, it is essential to avoid rubbing your eyes altogether.
How is it diagnosed?
Keratoconus is diagnosed through a comprehensive corneal study. A standard eye exam may not detect early stages of the disease. The key diagnostic tools include:
Corneal topography
Maps the curvature of the corneal surface. Detects asymmetric steepening patterns characteristic of keratoconus.
Corneal tomography (Pentacam, MS-39)
Analyses the front and back surfaces of the cornea, its thickness profile, and elevation maps. Essential for early detection and staging.
Pachymetry
Measures corneal thickness at multiple points. Focal thinning is a hallmark of keratoconus.
Corneal OCT
High-resolution cross-sectional imaging of the cornea. Useful for monitoring subtle structural changes over time.
Early detection is critical: the sooner keratoconus is identified, the more options are available to prevent vision loss.
Treatment options
Click on each treatment to learn more about how it works and when it is indicated.
How it works
Riboflavin (vitamin B2) drops are applied to the cornea, which is then exposed to controlled ultraviolet-A light. This creates new chemical bonds between the collagen fibres of the cornea, strengthening its structure.
Goal
The primary goal of cross-linking is to halt the progression of keratoconus. It does not reverse existing damage, but it prevents further deterioration of the corneal shape.
When it is indicated
Patients with documented progression of keratoconus — increasing curvature, thinning, or worsening vision — confirmed by serial corneal imaging. It is most commonly performed in young patients where the disease is most likely to progress.
What to expect
The procedure takes approximately one hour per eye. Vision may be reduced for a few days to weeks after treatment while the corneal surface heals. Discomfort is common in the first 2–3 days. The structural reinforcement effect develops gradually over the following months.
Key point
Cross-linking is the only proven treatment to stop keratoconus progression. It is generally recommended as the first line of treatment when progression is documented.
How it works
Thin, arc-shaped segments of medical-grade polymethyl methacrylate (PMMA) are implanted within the corneal stroma — the middle layer of the cornea — through a small incision. They flatten and regularise the corneal curvature from the inside.
Goal
The goal is to improve the corneal shape enough to provide better visual acuity, either unaided or with glasses or contact lenses. They do not cure keratoconus, but they can significantly improve vision quality.
When it is indicated
Patients with moderate keratoconus who have poor vision despite glasses, and who are intolerant to or unable to achieve good correction with contact lenses. The cornea must have adequate thickness at the implantation site.
What to expect
The procedure is performed under topical anaesthesia and typically takes 15–20 minutes per eye. A femtosecond laser is often used to create the channels for segment placement, improving precision. Visual recovery varies: some patients notice improvement within days, while others may take weeks.
Key point
ICRS are reversible — the segments can be removed or exchanged if needed. They are often combined with cross-linking in a single or staged approach.
How it works
In many cases, CXL and ICRS can be combined — either in the same surgical session or in sequential procedures — to address both the structural weakness and the optical distortion of the cornea.
Goal
The combined approach aims to stabilise the cornea (CXL) while also improving its shape and the patient's vision (ICRS). This may reduce the need for a corneal transplant and improve long-term visual outcomes.
When it is indicated
Patients with progressive keratoconus who also have significant visual impairment. The decision to combine treatments is made on an individual basis, considering the degree of progression, corneal thickness, and visual needs.
What to expect
When performed together, cross-linking is typically done first (to strengthen the tissue), followed by segment implantation. In some protocols, both are performed in a single session. Your surgeon will explain the approach recommended for your case.
Key point
The combination of CXL and ICRS is one of the most effective conservative strategies currently available for managing keratoconus.
Other treatment options
Beyond CXL and ring segments, other approaches may be considered depending on the stage of keratoconus and the patient's visual needs:
Contact lenses
Rigid gas-permeable (RGP) lenses, scleral lenses, or hybrid lenses remain a cornerstone of visual rehabilitation in keratoconus. They create a smooth optical surface over the irregular cornea and provide better vision than glasses in most cases.
Corneal transplant (keratoplasty)
Reserved for advanced cases where other treatments cannot provide adequate vision or where the cornea has scarred significantly. Modern techniques (DALK — deep anterior lamellar keratoplasty) preserve the patient's own inner corneal layers, reducing rejection risk.
Topography-guided laser (limited cases)
In selected cases with a stable cornea (after CXL), a topography-guided laser ablation may be considered to reduce irregular astigmatism. This is a highly individualised decision, not appropriate for all patients.
Living with keratoconus
Stop rubbing your eyes. This is the single most important habit change. Eye rubbing is strongly linked to keratoconus progression.
Attend all scheduled follow-up appointments. Regular corneal imaging allows your ophthalmologist to detect any progression early.
Use artificial tears liberally if you have dry or itchy eyes — this reduces the urge to rub.
If you wear contact lenses, follow the care and replacement schedule strictly.
Protect your eyes from UV light with quality sunglasses.
Inform your ophthalmologist if your vision changes between visits.
Frequently Asked Questions
Have you been diagnosed with keratoconus?
If you have keratoconus or suspect you might, the most important step is a comprehensive corneal evaluation. Early detection and timely treatment can make a significant difference in preserving your vision.