Corneal Transplant: PK, DALK, DSAEK and DMEK Explained

Medically reviewed by Dr. Fouad El Sayyad, Consultant Ophthalmologist — Cornea, Cataract & Refractive Surgery · Last reviewed: October 2026

Quick answer: A corneal transplant (keratoplasty) replaces damaged corneal tissue with healthy donor tissue. Modern surgery replaces only the layer that is diseased: DALK for the front layers, DSAEK or DMEK for the inner layer, and a full-thickness transplant (PK) when all layers are affected. I perform all four at Sayyad Eye Center in Mohandeseen, Cairo.

Key Takeaways

• There are four main types of corneal transplant: PK, DALK, DSAEK and DMEK.
• Replacing only the diseased layer usually means faster recovery, and DMEK and DALK carry a lower risk of rejection than PK.
• Most donor corneas come from eye banks in the United States and Sri Lanka, and each one is checked by the eye bank.
• Recovery takes weeks to months after DMEK or DSAEK, and a year or more after PK or DALK.
• Rejection can be treated if caught early: redness, light sensitivity, pain or reduced vision need a same-day check.

What Is a Corneal Transplant?

The cornea is the clear front window of the eye. It has several layers: the surface epithelium, the thick middle stroma, and a single inner layer of cells (the endothelium) that pumps fluid out and keeps the cornea clear. When disease or injury damages these layers so that vision cannot be restored with glasses, contact lenses or other treatment, a corneal transplant replaces the damaged tissue with clear donor tissue.

What Are the Types of Corneal Transplant?

How Do I Choose the Right Type of Transplant?

I start by finding exactly which layer is damaged. At the slit lamp and with corneal imaging, I look at the depth of any scar, the shape and thickness of the cornea, and the health of the endothelium, and I check the eye pressure, the lens and the retina. Then:

• If only the inner layer has failed, as in Fuchs dystrophy, I recommend an endothelial transplant: DMEK in most suitable eyes, or DSAEK when the eye is more complex, for example after previous surgery or glaucoma surgery. Recent meta-analyses found sharper vision after DMEK, while a second bubble was needed less often after ultrathin DSAEK.
• If the front layers are damaged but the inner layer is healthy, as in advanced keratoconus or many scars, DALK keeps your own endothelium, which cannot be rejected.
• If all layers are affected, or a previous graft has failed, PK is the right choice. Occasionally, a planned DALK is converted to PK during surgery when that is safer.

Where Do the Donor Corneas Come From?

Donor corneas come from people who chose to donate after death. Most of the corneas I use are imported from eye banks in the United States and Sri Lanka. The eye bank screens each donor and examines the tissue, including the endothelial cell count, before releasing it. Surgery is scheduled according to medical need and tissue availability.

What Happens on the Day of Surgery?

Corneal transplants are performed at the main Sayyad Eye Center branch in Mohandeseen. Most are done under local anaesthesia, with the eye numbed by an injection around it, sometimes with mild sedation; general anaesthesia is used for children and some special cases. In DMEK and DSAEK, the thin graft is rolled or folded, inserted through a small incision and held against the back of the cornea with an air or gas bubble. I prepare every DMEK and DSAEK graft myself during the surgery. In PK and DALK, the graft is fixed with fine stitches. The operation usually takes 45 minutes to an hour and a half, and sometimes longer in complex or combined cases. Cataract surgery can sometimes be combined with the transplant, or done before or after it.

Femtosecond laser-assisted keratoplasty is not part of my routine; it can be arranged at another facility on request.

What Is Recovery Like After a Corneal Transplant?

• After DMEK or DSAEK: lie flat on your back as instructed for the first few days, so the bubble presses the graft into place. Avoid sujood or bending your head downwards for the first week, and do not fly while a gas bubble remains in the eye. Vision improves over weeks and keeps improving for months. Sometimes part of the graft separates and a second bubble (rebubbling) is needed; this does not mean the graft has failed.
• After PK: keep water out of the eye and do not sleep on the operated side for the first one to two weeks, and avoid sujood or bending your head downwards for the first two weeks. Vision improves slowly as the cornea heals and the stitches are adjusted; the stitches usually come out at 12–18 months.
• After DALK: recovery is similar to PK, with stitches and gradual improvement, but without the risk of endothelial rejection. Avoid sujood or bending downwards for the first week.

For all types: use the steroid drops exactly as prescribed and never stop them on your own, avoid rubbing the eye, start light exercise after about four weeks, wait at least one month before swimming, and after PK wait six to eight weeks before going back to the gym or heavy lifting. Many patients still need glasses or contact lenses after a transplant, especially after PK or DALK, because of astigmatism.

What Are the Risks of a Corneal Transplant?

A corneal transplant is a major operation, and the risks depend on the type and on the eye. They include graft rejection, infection, raised eye pressure, graft detachment after DMEK or DSAEK, problems with stitches, astigmatism, and a graft that does not clear or fails later and needs to be repeated. DMEK and DALK have a lower risk of rejection than PK: in a 2025 study following patients for ten years, rejection occurred in about 10% of DMEK grafts, compared with 13% after PK and 19% after DSAEK, and a 2025 meta-analysis of more than 27,000 eyes with keratoconus found more rejection episodes after PK than after DALK. Read about the success rate of corneal transplants and rejection.

What Are the Signs of Graft Rejection?

Rejection can happen weeks or even years after surgery, and it can often be reversed if treated early. Contact us the same day if you notice:

• Redness of the operated eye
• Sensitivity to light
• Pain or discomfort
• A drop in vision or hazy vision

When Is a Corneal Transplant Needed?

A transplant is considered when lasting corneal damage limits vision despite other treatment, or urgently when infection or thinning threatens the eye. Many patients with keratoconus never need one. Read when a corneal transplant is needed, common corneal problems and the cost of a corneal transplant.

Where Does Dr. Fouad El Sayyad See Patients?

• Sayyad Eye Center, Mohandeseen (main branch, where cataract surgery and corneal transplants are performed): 3A Gameat El Dowal El Arabeya St., Sphinx Square.
• Sayyad Eye Center, New Cairo: Medical Park 2, opposite New Cairo Court.

To book an appointment with Dr. Fouad El Sayyad, call or WhatsApp 01000088168.

Frequently Asked Questions

What is the difference between DMEK and DSAEK?

Both replace only the inner cell layer of the cornea. DMEK transplants just that layer and its thin membrane and often gives faster, sharper vision. DSAEK includes a thin layer of supporting tissue, which makes it easier to handle in some complex eyes.

What is the difference between DALK and PK?

DALK replaces the front and middle layers and keeps your own inner cell layer, so that layer cannot be rejected. PK replaces all layers of the central cornea and is used when the damage is full thickness.

How long does a corneal transplant operation take?

Usually 45 minutes to an hour and a half, depending on the type, and sometimes longer in complex cases or when cataract surgery is combined. You go home the same day in most cases.

Is a corneal transplant painful?

The eye is numbed for surgery, so the operation itself is not painful. Discomfort, watering and light sensitivity are common for a few days afterwards.

When are the stitches removed after PK?

The stitches usually come out at 12–18 months. Some may be adjusted or removed earlier to reduce astigmatism.

How long does a corneal graft last?

Many grafts stay clear for many years. Some fail over time and can be replaced with another transplant. Regular follow-up and early treatment of rejection help the graft last longer.

When can I do sujood or bend down after a corneal transplant?

After PK, avoid sujood or bending your head downwards for two weeks. After DALK, DMEK or DSAEK, avoid it for one week. After DMEK or DSAEK, lying flat on your back for the first few days is also important.

Will I still need glasses after a corneal transplant?

Often, yes, especially after PK or DALK, because the new cornea may have some astigmatism. Glasses, contact lenses or, later, other treatments can improve vision further.

Where do the donor corneas come from?

Most of the donor corneas I use come from eye banks in the United States and Sri Lanka. Each cornea is screened and examined by the eye bank before it is released for surgery.

This article is for general education and does not replace an eye examination. Treatment decisions depend on your own eye assessment.

References

• Wilhelm TI, Gauché L, Böhringer D, et al. Ten-year outcomes after DMEK, DSAEK, and PK: insights on graft survival, endothelial cell density loss, rejection and visual acuity. Sci Rep. 2025;15(1):1249.
• Hurley DJ, Murtagh P, Guerin M. Ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) versus Descemet membrane endothelial keratoplasty (DMEK): a systematic review and meta-analysis. Eye (Lond). 2023;37(14):3026–3032.
• Maier AB, Milek J, Joussen AM, et al. Systematic review and meta-analysis: outcomes after Descemet membrane endothelial keratoplasty versus ultrathin Descemet stripping automated endothelial keratoplasty. Am J Ophthalmol. 2023;245:222–232.
• Awad AA, Elettreby AM, Abo Elnaga AA, et al. Penetrating keratoplasty versus deep anterior lamellar keratoplasty for keratoconus: a systematic review and meta-analysis of 27,018 eyes. Semin Ophthalmol. 2025;40(5):364–381.
• Romano V, Passaro ML, Bachmann B, et al. Combined or sequential DMEK in cases of cataract and Fuchs endothelial corneal dystrophy: a systematic review and meta-analysis. Acta Ophthalmol. 2024;102(1):e22–e30.