This study provides results of an extensive evaluation of a DALK patient who developed conjunctival intraepithelial neoplasia grade 3 in an eye previously treated with CXL.
This is a very interesting case report that should be of interest to anyone currently performing corneal collagen crosslinking. The authors speculate that increased proliferation or overactivation of limbal stem cells following DALK may contribute to the pathologic changes in a previously crosslinked cornea.
A healthy 49-year-old male patient underwent bilateral CXL according to the Dresden protocol for progressive keratoconus stage 3. BCVA did not reach better than 20/100 within two years after surgery, and contact lenses were not tolerated. Consequently, unilateral DALK was performed to transplant an 8-mm fully epithelialized button onto an 8-mm bed with a bared Descemet membrane.
The postoperative healing course was unusually disturbed. Sutures pulled through the recipient tissue, which required suture replacement. Portions of the epithelium sloughed off repeatedly, and bulky regrowth displayed no attachment to the Bowman membrane. Within the first weeks, the transplant became cloudy.
Two biopsies from the limbus area showed the condition as conjunctival intraepithelial neoplasia, the preliminary stage of invasive squamous cell carcinoma. Pathology tests indicated conjunctival intraepithelial neoplasia in the keratocyte-voided bed of the recipient.
The authors note that this is the third case of conjunctival intraepithelial neoplasia grade 3 subsequent to DALK in eyes previously treated with CXL in their clinic. The first two cases exhibited similar symptoms: weak epithelium, sloughing off and neovascularization of the transplant within three weeks of surgery. However, these patients were lost to follow-up.
This association between corneal collagen crosslinking, subsequent corneal surgery, and the development of conjunctival intraepithelial neoplasia needs to be further evaluated and other similar cases identified. With the increasing popularity of corneal collagen crosslinking, surgeons should exercise caution in light of these findings until the true impact can be further elucidated and this sort of sequential surgery found to be safe.