What cross-linking does, and what it doesn’t
Corneal cross-linking is a procedure that stiffens the cornea (the clear front window of the eye) so it stops bulging further. In the standard method the surgeon removes the surface layer of the cornea, applies riboflavin (vitamin B2) drops, then shines ultraviolet light on the eye. The FDA approved the first cross-linking system in the US in 2016, for progressive keratoconus and for corneal ectasia after refractive surgery.[1]
It works at what it’s meant to do. In a randomized trial of 60 young people aged 10 to 16 with progressive keratoconus, the disease progressed in 7% of cross-linked eyes compared with 43% of eyes given standard care.[2]
It doesn’t give you a normal cornea. In the two trials behind the US approval, the steepest point of the cornea flattened by an average of 1.4 to 1.7 diopters at one year.[1] That’s a small change next to the distortion many people with keratoconus have. The cornea stays irregular, and glasses often still can’t correct it well. That is why so many people wear a scleral lens after cross-linking: the procedure aims to hold the cornea steady, and the lens provides the clear vision.
Why timing is a question for your surgeon
Cross-linking leaves the eye with a healing period, and lens wear has to fit around it. In the US trials, the most common side effects in cross-linked keratoconus eyes were haze in the cornea, small surface spots, faint lines in the cornea, an open wound where the surface layer was removed, eye pain, and blurred vision.[1]
- Haze was common. It was reported in 64% of cross-linked keratoconus patients in the first three months.[1]
- Most effects settled within a month. Some, such as the surface wound, dry eye, eye pain, light sensitivity, and reduced vision, took up to six months. Haze took up to 12 months. In 1 to 2% of patients, some changes were still present at a year.[1]
How quickly a scleral lens can go back in depends on how your eye heals, which technique was used, and what your surgeon sees at follow-up. Published studies give a sense of the spread, not a rule. In one study of 23 eyes, the time between cross-linking and a scleral lens prescription ranged from 1 to 33 months.[5] Another small study suggested that people already fitted before the procedure could safely resume wear one month afterwards.[4] Your surgeon and fitter will set your timing.
How a scleral lens works after cross-linking
A scleral lens is a large rigid gas-permeable lens. It rests on the sclera (the white of the eye) and arches over the entire cornea without touching it. Before insertion it is filled with sterile saline, so a layer of fluid sits between the lens and the cornea.
The fluid fills in the irregular shape of the cornea. Light passes through the smooth front of the lens and an even layer of fluid, which largely cancels out the irregularity. Because the lens doesn’t rest on the cornea, the treated cornea doesn’t carry the lens’s weight.
What the research shows
The studies are small, and each looked at a slightly different question.
- Lens tolerance stays stable. A study followed 18 eyes that had worn well-fitting scleral lenses for at least three months before cross-linking. One year after the procedure, vision with the lenses was unchanged and wearers still wore them a median of 16 hours a day with stable comfort. But 61% of eyes needed a change to the lens fit, the power, or both.[3]
- A fit done before cross-linking often still works. A study of 11 eyes in seven people with keratoconus or ectasia after LASIK fitted the lenses first, then performed cross-linking. On average, corneal measurements and the lens prescription had not changed significantly three months later.[4]
- Vision is better with the lens than without it. A Korean study of 23 eyes that started scleral lenses after cross-linking found vision with the lens was better than with the people’s previous correction at every visit over a year. Corneal measurements stayed stable during that year.[5] That study only included people who kept wearing their lenses for at least a year, so it doesn’t tell you how many people stop.
- Lens wear can mask changes. A study of 14 eyes measured the cornea before and after a few hours of scleral lens wear. The cornea flattened slightly with wear, in both cross-linked and untreated eyes. The authors warned that scleral lens wear may hide signs of progression, and that cross-linking doesn’t guarantee the cornea’s shape is stable.[6]
Other options, compared
After cross-linking you have the same vision options as anyone with keratoconus or ectasia. Which one suits you depends on how irregular your cornea still is.
| Option | What it does | Typically suited to |
|---|---|---|
| Glasses | Correct regular blur only | Mild cases with little irregularity |
| Soft or specialty soft lenses | Mask mild irregularity | Mild cases |
| Corneal rigid gas-permeable lenses | Give a smooth optical surface on the cornea | Mild to moderate cases where the lens centers and is comfortable |
| Hybrid lenses | Rigid center with a soft skirt | People who can’t tolerate a corneal rigid lens |
| Scleral lenses | Vault the whole cornea over a fluid layer | Moderate to severe irregularity, or failure of the options above |
| Corneal transplant | Replaces corneal tissue | Scarring or intolerance of every lens option |
Questions to ask your surgeon and fitter
- When do you want me to stop wearing my lenses before cross-linking, and when can I restart?
- Should I be fitted before the procedure, or wait until the cornea settles?
- Will my current scleral lenses need to be refitted afterwards?
- How long should I leave my lenses out before scans that check for progression?
- Will my surgeon and fitter share results so both know how the cornea is changing?
- How many visits does a refit usually take, and what do the fees cover?
- What signs mean I should remove the lens and call you the same day?
Common questions
How soon after cross-linking can I wear my scleral lenses again?
Your surgeon decides, based on how your eye is healing. The surface of the cornea is removed during standard cross-linking and has to grow back, and haze and other changes can take months to settle. Don't restart lens wear until your surgeon and fitter both say it's time.
Will my old scleral lenses still fit after cross-linking?
Maybe not exactly. In a study of 18 eyes that wore scleral lenses before cross-linking, vision with the lenses was unchanged a year later, but 61% of eyes needed the fit or the power adjusted. Plan on at least one refitting visit.
Should I get fitted before or after cross-linking?
Practices differ. A small study suggested a fit done before the procedure can often still be used afterwards, which may get you seeing well sooner. Others wait until the cornea has settled. Ask your surgeon and fitter which approach they prefer and why.
Does cross-linking mean I won't need lenses?
Usually not. Cross-linking aims to stop the cornea getting worse. It flattens the cornea only a little on average, so most people still need glasses or specialty contact lenses to see clearly afterwards.
Can wearing scleral lenses hide keratoconus getting worse after cross-linking?
It can make it harder to spot. A small study found that a few hours of scleral lens wear slightly flattened the cornea's measurements, in eyes with and without cross-linking. Ask your doctors whether you should leave the lenses out for a while before scans that check for progression.
What is recovery from cross-linking like?
Many people say the procedure itself was easier than they expected and the first few days afterward were the hardest, with eye pain and light sensitivity. Recovery varies with the technique your surgeon uses. Ask before the day how pain will be managed and what to do if it gets worse, and follow your surgeon's aftercare instructions closely.
Can I have LASIK or PRK after cross-linking to get rid of my lenses?
Cross-linking stabilizes a weakened cornea but doesn't make it a normal cornea, so laser vision surgery needs very careful assessment. Many cornea specialists advise against it for eyes with keratoconus or ectasia. Ask your cornea surgeon directly which options are safe for your eye.
What if I'm told I'm not a candidate for cross-linking?
Cross-linking isn't right for every eye, for example when the cornea is very thin, scarred, or already stable. Ask your surgeon to explain the reason and how they plan to watch for changes. A scleral lens doesn't depend on cross-linking, so it can still be an option for clear vision.
Should I update my glasses after cross-linking?
Glasses often can't match the vision a scleral lens gives on an irregular cornea, but a backup pair still matters for times your lenses are out. Ask your eye doctor for the most useful glasses prescription once your eye has settled. Some people find glasses help only a little, and that's common with keratoconus.