Keratoplasty is the medical term for a corneal transplant, a surgery that removes damaged or diseased corneal tissue and replaces it with healthy tissue from a donor. It’s one of the most commonly performed tissue transplants in the world, and the technique has evolved significantly: surgeons can now replace the full thickness of the cornea or target only the specific layers that are damaged, leading to faster recovery and better outcomes for many patients.
Why Corneal Transplants Are Needed
The cornea is the clear, dome-shaped front surface of your eye. It does most of the work of focusing light, so when it becomes cloudy, scarred, or misshapen, vision deteriorates in ways that glasses or contacts can’t fully correct. The most common reasons people need keratoplasty include swelling of the cornea after cataract surgery (called bullous keratopathy), scarring from eye infections, traumatic corneal scars, and progressive conditions like keratoconus, where the cornea thins and bulges into a cone shape. Corneal degenerations that develop with age can also reach a point where transplant becomes the best option.
Types of Keratoplasty
Not every corneal problem requires replacing the entire cornea. Modern surgical techniques let surgeons target the exact layer that’s failing, which generally means fewer complications and faster visual recovery. The three main categories are full-thickness transplants, front-layer transplants, and back-layer transplants.
Full-Thickness (Penetrating Keratoplasty)
Penetrating keratoplasty, often shortened to PK, is the traditional approach. The surgeon removes a circular disc of the entire cornea and replaces it with a matching full-thickness disc from a donor. This is still the go-to procedure when damage extends through all layers of the cornea, such as after severe trauma or deep infection. The tradeoff is a longer recovery period. Vision typically improves gradually, and maximum visual recovery takes about 18 to 24 months, often not reaching its best until all sutures are removed.
Front-Layer (Deep Anterior Lamellar Keratoplasty)
Deep anterior lamellar keratoplasty, or DALK, replaces the front and middle layers of the cornea while leaving your own innermost layer (the endothelium) intact. This is a major advantage for conditions like keratoconus, where the back layer of the cornea is still healthy. Because the body’s immune system is most likely to attack transplanted endothelial cells, keeping your own eliminates the risk of endothelial graft rejection entirely.
Studies comparing DALK to full-thickness transplants for keratoconus have found that DALK patients experience less cell loss from the inner corneal layer, have no graft failures related to rejection, and avoid the rise in eye pressure that sometimes follows PK. The postoperative course is also lighter: patients need a less aggressive steroid regimen, reach graft stability sooner, and have sutures removed earlier. Visual outcomes are similar to, and in some cases better than, full-thickness transplants.
Back-Layer (Endothelial Keratoplasty)
When the problem is limited to the innermost cell layer, surgeons can replace just that layer and leave the front of your cornea untouched. Two techniques dominate this category: DSAEK and DMEK.
In DSAEK, an automated instrument separates a thin layer (50 to 150 microns thick) from the back of the donor cornea, including some supportive tissue along with the endothelial cells. In DMEK, the surgeon peels off only the endothelial cell layer and its basement membrane, a sheet roughly 15 microns thick. That’s about one-tenth the thickness of a DSAEK graft. Thinner grafts are associated with faster visual rehabilitation and better overall visual outcomes, which has made DMEK increasingly popular. The main complication with both procedures is graft dislocation, which typically happens within days or weeks after surgery and is treated by injecting an air bubble into the eye to reattach the graft.
How Donor Corneas Are Screened
Donor corneas come from eye banks, which follow strict screening protocols. Every donor is tested for HIV (types 1 and 2), hepatitis B, hepatitis C, and syphilis. The donor also undergoes a physical assessment for signs of infection or intravenous drug use. Beyond infectious disease testing, eye banks maintain a long list of conditions that disqualify donation, including prion diseases like Creutzfeldt-Jakob disease, active cancers of the blood or eye, prior refractive surgery on the cornea, and certain neurological conditions of unknown cause. These safeguards make disease transmission through corneal transplantation extremely rare.
What Recovery Looks Like
After any type of keratoplasty, you’ll use steroid eye drops to prevent your immune system from attacking the new tissue. The regimen typically starts intensive, with drops every few hours, then tapers gradually over 6 to 12 months. Many ophthalmologists recommend continuing a low-dose steroid drop once daily indefinitely, even for lower-risk procedures like DMEK, because the risk of rejection never fully disappears.
Recovery speed depends heavily on the type of procedure. Back-layer transplants (DMEK and DSAEK) tend to have the fastest visual recovery because the front surface of the cornea is never cut. DALK falls in the middle. Full-thickness PK is the slowest, with vision improving gradually over a year or more as the graft heals and sutures are removed. During this time, you’ll have regular follow-up visits to monitor healing, check eye pressure, and watch for signs of rejection.
Graft Survival Rates
Corneal transplants performed for vision correction (optical indications) have the best long-term survival: about 64% at five years and 52% at ten years for full-thickness grafts. Transplants done for other reasons, such as treating active infections or reinforcing a cornea at risk of perforation, have lower survival rates (37% at five years for therapeutic grafts). Newer partial-thickness techniques are expected to improve these numbers because they reduce the risk of immune rejection, which is the leading cause of graft failure.
Recognizing Graft Rejection
Between 18% and 21% of corneal graft recipients experience a rejection episode at some point after surgery. The most common type is endothelial rejection, accounting for about half of all rejection events, and it’s also the most serious because it threatens the cells that keep the cornea clear. Symptoms of endothelial rejection include blurred vision, eye pain, redness, and sensitivity to light. Front-layer rejection, by contrast, may cause only mild discomfort or no symptoms at all.
Rejection doesn’t mean the graft is lost. When caught early and treated aggressively with frequent steroid drops and sometimes oral steroids over 6 to 8 weeks, many rejection episodes can be reversed. The key is recognizing the warning signs quickly. If you notice a sudden drop in vision, new redness, or pain in the transplanted eye at any point, even years after surgery, getting to an eye specialist promptly makes a significant difference in outcome.
Laser-Assisted Keratoplasty
A growing number of surgeons use femtosecond lasers to cut the corneal tissue instead of a manual blade. The laser allows precisely shaped incision patterns, such as zigzag, top-hat, or mushroom configurations, that increase the contact area between the donor graft and your own cornea. This better fit promotes wound healing and improves structural stability.
Laser-assisted procedures have shown reduced astigmatism (uneven curvature that blurs vision) and faster early visual recovery compared to manual techniques. A 2021 meta-analysis of nearly 2,000 eyes found that laser-assisted full-thickness transplants produced significantly better visual acuity and less astigmatism at six months, though the differences leveled out by twelve months. Graft failure and rejection rates are comparable between the two approaches, so the main advantage of the laser is a smoother early recovery rather than a change in long-term graft survival. Mushroom-shaped cuts are particularly promising for children and patients with deep scars, because the larger front portion reduces astigmatism while the smaller back portion limits the amount of transplanted endothelial tissue exposed to the immune system.