Corneal transplantation: replacing only what is diseased
Full-thickness grafts are no longer the only option, and expectations have risen with the techniques.
The cornea is the transparent layer in front of the coloured part of the eye — comparable to the glass over a watch face. When it loses its transparency, or its shape is too distorted to correct, it can be replaced with clear corneal tissue from a donor.
In Türkiye the commonest reasons for transplantation are keratoconus, pseudophakic bullous keratopathy — persistent corneal swelling after cataract surgery — and corneal injury. Inherited corneal dystrophies and scarring from herpetic keratitis are also treated this way.
Full-thickness transplantation
In a penetrating graft the entire thickness of the cornea is replaced. It remains the right operation when the disease involves all the layers.
The trephination can be performed with the standard technique or with a femtosecond laser, which allows the donor and recipient edges to be cut in matching profiles rather than as a simple straight-sided disc.
DALK — replacing the front layers
In deep anterior lamellar keratoplasty the front layers of the cornea are replaced and the patient’s own innermost layer, the endothelium, is left in place.
DALK is used most often in keratoconus and in corneal injury, and in inherited dystrophies. As with every corneal graft, no tissue matching is needed — the cornea normally has no blood vessels.
DMEK — replacing only the innermost layer
When the disease is confined to the endothelium — as in bullous keratopathy, the persistent corneal swelling that can follow cataract surgery, or in inherited dystrophies — only that layer needs replacing. In DMEK the diseased endothelium is peeled away and the donor’s endothelium is transplanted in its place, leaving the rest of the patient’s cornea untouched.
What counts as success now
In earlier decades a transplant was considered successful if the tissue stayed clear and the patient saw well with glasses or a contact lens. Expectations are considerably higher now: the graft should stay clear and provide good vision without either.
That shift is what drives the current techniques — lamellar rather than full-thickness grafts, femtosecond lasers for the cuts, a wider choice of anti-rejection drops, and personalised laser treatment afterwards to correct the myopia and astigmatism left behind by the graft.
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This article is for general information only and does not replace a medical examination or personalised medical advice.