DALK, PK yield similar visual outcomes despite perforation of Descemet's membrane

Ophthalmology. 2011;118(2):302-309.

Issue: March 10, 2011

Deep anterior lamellar keratoplasty and penetrating keratoplasty offered similar visual outcomes despite a complication associated with lamellar grafting, a study showed.

"At this moment, the relatively high incidence of Descemet's membrane perforation in DALK warrants the presence of a donor cornea with good endothelial vitality because the donor cornea has to be suitable for a PK in case of conversion," the study authors said.

The randomized, multicenter clinical trial included 56 eyes of 56 patients with corneal stromal pathology that did not affect the endothelium. Twenty-eight patients underwent PK and 28 patients underwent DALK; however, five patients in the DALK group were converted to PK because of Descemet's membrane perforation.

All DALK procedures were performed with Anwar's big-bubble technique.

Patients underwent complete ophthalmic examination preoperatively and at 3, 6 and 12 months postoperatively.

At 12 months, endothelial cell loss was 27.7% in eyes in the PK group and 12.9% in eyes in the DALK group without perforation of Descemet's membrane. The difference was statistically significant (P = .007). However, both groups had similar endothelial cell loss when cases of Descemet's membrane perforation were included in the analysis.

PK eyes had significantly better uncorrected visual acuity than DALK eyes at 3 months. However, DALK eyes and PK eyes had similar UCVA at 6 and 12 months.

PK eyes had markedly better best corrected visual acuity than DALK eyes at 3 months and 6 months, but both groups had similar BCVA at 12 months. No graft failures were reported, the authors said.

This randomized study captures the key advantages and disadvantages of DALK vs. PK: DALK is more difficult to perform, but when performed successfully results in better preservation of the corneal endothelium and reduced risk of graft rejection. This should result in better long-term graft survival rates with DALK; hopefully the authors will continue to follow these patients to assess that. The visual and refractive outcomes were comparable for the two procedures at 1 year in this study. Interestingly the topical steroid regimen and rate of suture removal were also the same. In contrast, given the minimal risk of rejection, many surgeons taper steroids earlier after DALK; this can promote faster wound healing and allow earlier suture removal, a benefit for patients. The authors correctly conclude that further improvements are needed to standardize the DALK technique and allow more widespread adoption.

– Marianne O. Price, PhD
Executive Director Cornea Research Foundation of America, Indianapolis
Disclosure: Dr. Price has no financial interests to disclose.