How a corneal transplant changes your vision
A corneal transplant replaces damaged corneal tissue with donor tissue. In a full-thickness transplant, called penetrating keratoplasty (PK), a round button of the whole cornea is swapped out and stitched in place. In a deep anterior lamellar keratoplasty (DALK), only the front layers are replaced and the patient’s own inner layer stays. In endothelial keratoplasty, only the inner layer is replaced.
Transplants are common. US surgeons performed 43,873 corneal transplants in 2020 using tissue from US eye banks, a year when the pandemic cut volumes.[1] Of the main types that year, 26,095 were endothelial grafts, 15,402 were full-thickness grafts, and 505 were anterior lamellar grafts.[1] About 13% of all transplants were repeat grafts, replacing an earlier graft.[1]
A graft can be perfectly clear and still leave vision blurred. The new tissue rarely heals in as an even curve. Stitch tension, the way the graft and the patient’s own cornea knit together, and later suture removal all affect its shape. The result is often high or irregular astigmatism. Small amounts can be corrected with glasses. Larger amounts usually need contact lenses or further surgery.[2]
The numbers can be large. In an Israeli study of transplanted eyes fitted with scleral lenses, the average astigmatism was 8.0 diopters.[3] Glasses can’t correct irregular astigmatism well, and a big difference between the two eyes can make glasses uncomfortable to wear.
How a scleral lens works on a transplanted cornea
A scleral lens is a large rigid gas-permeable lens. It rests on the sclera (the white of the eye) and arches over the whole cornea, including the graft and the junction where it meets the patient’s own tissue. The lens is filled with sterile saline before it goes in, so a layer of fluid sits between the lens and the cornea.
That design suits a transplanted eye in two ways:
- It smooths out the graft optically. Light passes through the smooth front of the lens and the fluid layer. The fluid fills in the graft’s uneven surface, so most of the irregular astigmatism is cancelled out.
- It keeps the lens off the graft. Smaller rigid lenses sit directly on the cornea. On a graft with a raised or tilted junction they can rock, decenter, or rub. A scleral lens lands on the white of the eye instead.
In the published research, scleral lenses are the lens most often fitted after a transplant. A 2025 systematic review of 464 transplanted eyes found scleral lenses were the lens fitted in 61% of them. Nearly all of those eyes, 97%, had a full-thickness transplant.[5] There is far less published evidence specific to DALK.
The inner-cell question: why graft health matters
The cornea’s innermost layer, the endothelium, pumps fluid out of the cornea to keep it clear. Its cells don’t grow back. A transplant loses many of them: the authors of one 2026 study describe endothelial cell loss of about 80% after keratoplasty.[6] In the eyes they measured at least five years after surgery, cell density averaged about 780 cells per square millimeter.[6]
This matters because any lens that covers the cornea reduces the oxygen reaching it, and a cornea short on oxygen tends to swell. A healthy cornea handles that easily. A graft with fewer pump cells has less reserve.
- Grafts swell more under a scleral lens. In a study of nine transplanted eyes, about six hours of scleral lens wear caused about three times as much corneal swelling as in healthy eyes, an average of about 3%. Swelling was greatest toward the lower edge of the graft.[7]
- Lens design makes a difference. In the 2026 study, lower central cell density was linked to more swelling during lens wear. Corneal rigid lenses and larger scleral lenses caused more swelling than no lens, while smaller scleral lenses did not. The authors noted cell count alone was not a reliable predictor of who would swell.[6]
- A trial lens can help sort it out. Scanning the cornea’s thickness before and after a period of lens wear can show whether swelling comes from the lens or from a graft that is failing on its own. That distinction decides whether the answer is a different lens or more surgery.[8]
Case reports show what can go wrong. One patient developed lens-related corneal swelling several months after being refitted following a graft rejection episode.[9] Another report described three patients with transplants more than 30 years old who developed sudden, painful swelling in the graft. Two of the episodes happened soon after a scleral lens refit, which the authors noted suggests some association.[10]
Know the signs of graft rejection. Rejection is when the body’s immune system attacks the donor tissue. It can happen years after surgery, with or without a lens. Warning signs include redness, new sensitivity to light, blurrier vision, and eye pain in the transplanted eye. Anyone with a graft should know these signs and call their surgeon promptly if they appear.
What the research shows
Most transplanted eyes see well with a scleral lens. At a US university eye center, 44 of 48 transplanted eyes (91.7%) reached 20/40 or better with a scleral lens. Vision improved by an average of two lines on the eye chart compared with glasses or an earlier contact lens.[4] In the Israeli study, 82% of patients reached functional vision, and 28 of 31 patients were still wearing their lenses, with average follow-up of about five years. The time from transplant to first fitting ranged from 0.7 to 36 years.[3]
Every study in the systematic review reported better vision. Across 15 studies, all found a significant improvement in visual acuity with contact lenses after a transplant. Most patients could wear their lenses comfortably for 8 to 12 hours a day.[5]
Rejection and infection still show up in these groups. In the Israeli study, 30% of eyes had at least one rejection episode and 6% had an eye infection over follow-up of up to nine years.[3] In the US series, 12.5% of eyes had a rejection episode, and half of those went back to scleral lens wear. There were no infections.[4] These studies weren’t designed to show whether the lenses caused rejection. Grafts can reject without any lens. The findings are a reason for regular graft checks, not a verdict against lens wear.
A separate report described eye infections in three scleral lens wearers with transplants. All three also had dry or exposed eyes and were taking drugs that suppress the immune system. The authors concluded these patients should be monitored closely.[11]
Other options, compared
| Option | What it does | Typically suited to |
|---|---|---|
| Glasses | Correct regular blur only | Low, fairly regular astigmatism after the graft settles |
| Suture adjustment or removal | Changes graft shape while stitches are still in | Early high astigmatism, guided by the surgeon |
| Soft toric lenses | Correct moderate regular astigmatism | Milder, fairly regular cases |
| Corneal rigid gas-permeable lenses | Give a smooth optical surface on the cornea | Grafts where a small lens centers and stays comfortable |
| Hybrid lenses | Rigid center with a soft skirt | People who can’t tolerate a corneal rigid lens |
| Scleral lenses | Vault the whole graft over a fluid layer | High or irregular astigmatism, or failure of the options above |
| Relaxing incisions or laser surgery | Reshape the graft surgically | Selected eyes, chosen by the corneal surgeon |
| Repeat transplant | Replaces a failed or badly shaped graft | Graft failure, or when no lens gives usable vision |
Questions to ask a scleral lens fitter
- How many patients with corneal transplants do you fit, and do you work directly with my corneal surgeon?
- Will you measure my graft’s inner cell count or check how my cornea swells with a trial lens?
- How will you design the lens to limit swelling of my graft?
- How often will you check my graft once I’m wearing the lens?
- What should I do if I notice redness, light sensitivity, blurrier vision, or pain?
- How many visits does a fit usually take, and what do the fees cover?
Common questions
How soon after a corneal transplant can I be fitted for a scleral lens?
That is your corneal surgeon's call. Fitting usually waits until the graft is stable and the surgeon is done adjusting or removing stitches. In one long-term study, fitting happened anywhere from under a year to decades after surgery.
Can a scleral lens cause my graft to reject?
Rejection episodes have been reported in scleral lens wearers after a transplant, but grafts can reject with or without a lens, and the studies weren't designed to show the lens caused them. Because the risk is real either way, your fitter and surgeon should both be watching the graft.
What are the warning signs of graft rejection?
Redness, new sensitivity to light, blurrier vision, or eye pain in the transplanted eye. If you notice any of these, remove the lens and call your corneal surgeon the same day.
My graft is decades old. Is that a problem for scleral lens wear?
It can be. Older grafts have had more time to lose inner corneal cells, and some develop new bulging at the edge of the graft. Your fitter may check how your cornea handles a trial lens before committing to a design.
Will a scleral lens help if I had DALK instead of a full-thickness transplant?
Often, since irregular astigmatism can follow any graft. Most published studies involve full-thickness transplants, so there is less direct evidence for DALK. Ask your fitter how they would approach your eye.
Can I keep wearing my old scleral lens after a new transplant?
Usually not. A new graft changes the shape of the cornea, and wearers who have had more than one transplant commonly needed new lenses each time. Don't put an old lens back on a new graft until your fitter has examined the eye and checked the fit.
Is a transplant a way to avoid wearing scleral lenses?
Not usually. A graft can be perfectly clear and still leave irregular astigmatism, so many people need a specialty lens afterward anyway. Grafts can also reject or need replacing, which is why many specialists see a transplant as a later option when lenses can't give usable vision.
Can I nap in my scleral lens if I have a graft?
No. A graft has fewer of the inner cells that keep the cornea clear, so it has less reserve when oxygen is reduced, and sleeping in a lens reduces it further. Take the lens out before any sleep, including a short nap, unless your surgeon has prescribed otherwise.
My vision in the transplanted eye suddenly turned hazy. What should I do?
Remove the lens and call your corneal surgeon today. Sudden haze can come from corneal swelling, a rejection episode, or a problem elsewhere in the eye, and only an exam can tell which. Don't wait to see whether it clears on its own.
The lens on my graft still feels tight after several tries. Are there other options?
Often, yes. Scleral lenses come in many sizes and designs, and features such as channels or a different landing shape can change how a lens sits on an uneven graft. Tell your fitter exactly what you feel and when, and ask whether they work with more than one design.
Are there any special precautions for handling a lens over a graft?
Be gentle, take your time, and work over a clean towel so a dropped lens is easy to find. Never rub the eye, keep your plunger clean, and follow your fitter's removal technique closely, since an awkward removal can scrape a graft. If the eye is painful or red after handling, call your fitter.