The conventional full-thickness cornea transplant (PKP) is now reserved for more complex corneal disease. Today, there are many options for transplantation that involve transplanting only the diseased part of the cornea. Today’s discussion will focus on a technique where we replace just the front part of the cornea. This is known as a Deep Anterior Lamellar Keratoplasty (DALK).
Many eye diseases can be isolated just to the front part of the cornea, including keratoconus, corneal scars, corneal dystrophies and ectasia. If the disease only affects the front part of the cornea, there’s an advatage to just replace the front. It can translate into faster healing and lower rejection rate. The endothelium of the donor cornea contributes the most to a rejection later on, but in DALK we don’t transplant that layer – so it drastically reduces the rate of rejection (see Diagram above).
Unfortunately, planning for a DALK surgery is easier than doing the actual surgery. There are things that can come up and be detected during surgery, where the surgeon will convert to doing a full-thickness cornea transplant instead. For example, if the disease entity turns out to have involved the full-thickness of the cornea – undetected on the exam – the surgeon will need to change the procedure intraoperatively. All said, if a DALK can performed, it’s always the better option.
Below is a before and after picture of a patient with Hurler’s Syndrome with a cloudy cornea, who received a DALK transplant (the black strands you see are stitches).