Patient guide
Keratoconus: when the cornea changes shape
Call the same day for a sudden drop in vision with a new white or cloudy patch on the front of the eye, or an eye that is red, painful and sensitive to light, especially if you wear contact lenses. You can contact the office at (609) 246-0236. If the office is closed, or you cannot reach us, go to a hospital emergency room — most have an ophthalmologist on call.
Keratoconus is a condition in which the cornea, the clear dome at the front of the eye, slowly thins and bulges forward into a cone shape. The cornea does most of the eye's focusing, so when its shape becomes uneven, vision becomes blurred and distorted in a way that glasses can only partly fix.
This guide covers how it shows up, who is more likely to have it, how it is found and followed, the treatment that can stop it getting worse, the lenses that bring vision back into focus, and the habit that matters most at home.
What keratoconus is
A healthy cornea is an even, smooth curve, a little like the face of a watch. Its strength comes from layers of fibers held together by links between them. In keratoconus those fibers are weaker, so the cornea thins, usually in the lower middle, and the thin part pushes forward.
Healthy cornea. An even curve of the same thickness, so light is focused to one sharp point.
Keratoconus. The cornea thins and bulges into a cone (gold circle), so light is scattered instead of focused.
It usually starts in the late teens or early twenties and tends to get worse slowly over about 10 to 20 years, then often settles. It usually affects both eyes, often one much more than the other, so one eye can be quite blurred while the other still sees well.
It was once thought to be rare. A nationwide study of 4.4 million insured people in the Netherlands estimated that about 1 in 375 people has it, far more than older figures suggested, partly because better measurements now find milder cases.
Signs to notice
Early keratoconus can look like ordinary astigmatism, and the first glasses may work well. These are the signs that something more is going on:
- A glasses prescription that keeps changing, especially more astigmatism each year
- Vision that is not fully sharp even with new glasses
- Ghost images or doubling in one eye, lines that look bent or wavy
- Glare, halos and streaks around lights, worst when driving at night
- Soft contact lenses that no longer give clear vision
None of these proves keratoconus; each has other causes. A teenager or young adult whose glasses never seem quite right is worth checking for it.
When it changes suddenly
Rarely, in an advanced cone, fluid breaks into the cornea through a tiny split in its back layer. Vision in that eye drops over hours, a white or cloudy patch appears, and the eye is often watery and sore. It usually settles over weeks to months, but it needs to be seen the same day, as in the box at the top of this page.
Who is more likely to have it
No one cause is known. These raise the chance:
- Eye rubbingFrequent, hard rubbing is one of the strongest links found in studies, and the one you can change. See the section on rubbing below.
- Allergies, eczema and asthmaItchy eyes lead to rubbing, which is thought to be much of the reason for this link.
- Family historyAbout 1 in 10 people with keratoconus has a parent who has it. Brothers, sisters and children of someone with it are worth checking.
- Certain conditionsDown syndrome, and connective tissue conditions such as Ehlers-Danlos syndrome and Marfan syndrome.
Keratoconus is not caused by reading, screens, or wearing glasses or contact lenses.
How it is found and followed
At an eye exam, keratoconus often first shows up as astigmatism that has an uneven pattern, or as glasses that cannot bring vision up to where it should be. A close look at the cornea with the microscope can show thinning and other signs, though early on the cornea can look normal.
When we suspect it, a detailed map of the shape of your cornea is taken in this office. It needs no drops, and nothing touches the eye. The map shows the cone, how steep it is and where it sits.
One map gives the diagnosis. What decides treatment is whether the cornea is still changing, so the map is repeated at later visits and compared. That is why follow-up visits matter even when you feel your vision is the same.
- Diagnosis, with your prescription, a look at the cornea and a map of its shape.
- Follow-up maps, usually within months at first, to see whether it is changing.
- Referral to a corneal surgeon to discuss cross-linking if the maps show it is getting worse, or sooner for a teenager or young adult, in whom it tends to move faster.
- Glasses or lenses to keep you seeing well, at every stage.
Cross-linking: stopping it getting worse
Corneal cross-linking is the only treatment approved by the FDA to stop keratoconus from getting worse.
Riboflavin (vitamin B2) drops are put on the cornea, then the eye is treated with a measured dose of ultraviolet light. Together they create new links between the cornea's fibers, making it stiffer, so the cone stops pushing forward. It is done in one visit, as an outpatient treatment, by a corneal surgeon.
There are now two FDA-approved ways of doing it:
- Epithelium-off, approved in 2016. The thin surface layer of the cornea is removed first so the drops soak in. The eye is sore for a few days while that layer grows back, and vision takes a while to settle.
- Epithelium-on, approved in October 2025. The surface layer is left in place, which makes for an easier recovery.
Both are approved for teens and adults. Your corneal surgeon will say which suits your eye and when to treat.
What to expect, plainly: cross-linking is meant to hold the cornea where it is. It does not remove the cone, and it cannot promise any particular result. Some corneas flatten a little afterwards; most people still need glasses or lenses. That is why it does the most good early, before much vision has been lost.
Other procedures
Small curved ring segments placed inside the cornea can flatten the cone in some eyes. A corneal transplant, replacing part or all of the cornea with donor tissue, is for advanced cases where lenses no longer give useful vision or the cornea has scarred. In the Netherlands, the number of transplants for keratoconus fell after cross-linking came into use.
Seeing clearly: glasses and lenses
Cross-linking stops the change. Lenses are what bring vision back into focus, at every stage.
- Glasses or soft contact lensesOften enough early on, while the cone is mild.
- Rigid gas permeable lensesA firm lens that sits on the cornea. The tears fill the gap under it, so the eye focuses through the lens's smooth surface instead of the uneven cornea.
- Hybrid lensesA rigid center with a soft outer ring, for people who find a rigid lens uncomfortable.
- Scleral lensesA larger rigid lens that rests on the white of the eye and vaults over the cornea on a layer of saline. Often comfortable even with a steep or irregular cone.
The rigid lenses take several visits to fit, because each cone is shaped differently. If you need one, we explain which kind suits your eyes and arrange the fitting.
Keratoconus and LASIK
LASIK removes corneal tissue, which would weaken a cornea that is already weak, so keratoconus usually rules it out. That is one reason a LASIK consultation includes measuring the shape and thickness of the cornea. If you have keratoconus, or were told you are not a LASIK candidate because of your cornea, other options can be discussed.
The most useful habit: stop rubbing
Rubbing presses on a cornea that is already weak, and it is the one risk you control. This matters most for anyone with keratoconus, anyone in a family with it, and anyone with itchy, allergic eyes.
- Treat the itch. Allergy eye drops, used every day in allergy season, take away much of the urge. Ask which kind suits you.
- Cool, not rub. A cold compress or chilled preservative-free tears calm an itchy eye without pressing on it.
- Notice when you do it. Many people rub on waking, when tired, or after taking out contact lenses, often without knowing.
- Sleep position. Sleeping with an eye pressed into the pillow or an arm is also pressure on the cornea.
- Children and teens. If your child rubs a lot, mention it at the exam, especially if keratoconus runs in the family.
Common questions
Will I go blind?
Keratoconus does not cause total blindness. It can blur vision badly, but the aim of care is to keep you seeing well enough for daily life: cross-linking to stop the change, and lenses to sharpen vision when glasses no longer can.
Will it keep getting worse?
It often changes most in the teens and twenties and tends to slow down by the thirties or forties, but no one can say in advance how far a given eye will go. That is what the repeated maps are for. Once a cornea has been cross-linked, it is followed to make sure it has stayed stable.
Is cross-linking painful?
The eye is numbed during treatment. With the epithelium-off method the eye is sore for a few days afterwards; the epithelium-on method avoids most of that. Your corneal surgeon will explain recovery for the method they recommend.
Should my children be checked?
Yes, if a parent or sibling has keratoconus, a full eye exam is worthwhile, and again through the teen years, when it often starts. Tell us about the family history so the cornea can be mapped if anything looks uneven. We examine children from age five.
Can I still wear contact lenses after cross-linking?
Yes. After the epithelium-off method, lenses are stopped until the surface has healed; after the epithelium-on method the break is usually shorter. Your corneal surgeon will say when.
Does this go through my vision plan or my medical insurance?
Visits to diagnose and follow keratoconus are usually medical visits and go through your medical insurance. Some vision plans help with the cost of contact lenses that are needed for a medical reason such as keratoconus. If you are not sure which plan applies to your visit, or whether a test carries a charge on your plan, call and we will check before your appointment rather than after. Vision plan or medical insurance explains the difference.
Book an eye exam
An exam checks your prescription and the health of each eye, and maps the cornea when keratoconus is suspected or runs in the family.
Book an exam Call (609) 246-0236
Khoury Eye Care, Hamilton Mall, 4403 Black Horse Pike, Mays Landing.
Sources
The figures and recommendations on this page come from the following. Ask at your visit if you would like a copy of any of them.
- Godefrooij DA, de Wit GA, Uiterwaal CS, et al. Age-specific incidence and prevalence of keratoconus: a nationwide registration study. American Journal of Ophthalmology. 2017;175:169-172.
- Godefrooij DA, Gans R, Imhof SM, Wisse RPL. Nationwide reduction in the number of corneal transplantations for keratoconus following the implementation of cross-linking. Acta Ophthalmologica. 2016;94(7):675-678.
- Gomes JAP, Tan D, Rapuano CJ, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34(4):359-369.
- Hashemi H, Heydarian S, Hooshmand E, et al. The prevalence and risk factors for keratoconus: a systematic review and meta-analysis. Cornea. 2020;39(2):263-270.
- US Food and Drug Administration. Approval of Photrexa riboflavin solutions with the KXL System for corneal cross-linking, April 2016; approval of Epioxa for epithelium-on cross-linking in patients aged 13 and older, October 2025.