Modified lamellar keratoplasty technique yields optimal visual outcomes and high graft survival rate

Am J Ophthalmol. 2009;148(5):744-751.

Issue: January 25, 2010

A modified deep anterior lamellar keratoplasty technique for keratoconus resulted in better visual outcomes than manual deep anterior lamellar keratoplasty or penetrating keratoplasty, according to a study.

The authors set out to compare the outcomes of penetrating keratoplasty, the modified Anwar technique of deep anterior lamellar keratoplasty and manual deep anterior lamellar keratoplasty.

The retrospective cohort study included 100 PK procedures and 25 deep anterior lamellar keratoplasty procedures performed at one center between April 1992 and December 2006. Modified deep anterior lamellar keratoplasty was performed in 14 eyes and a manual version of the technique was performed in 11 eyes.

Study data showed that at 12 months, the modified lamellar keratoplasty eyes had mean logMAR best corrected visual acuity of 0.15 and the PK eyes had a mean logMAR BCVA of 0.27. The manual lamellar keratoplasty eyes had a mean logMAR BCVA of 0.41. The difference between the modified and manual lamellar keratoplasty eyes was statistically significant (P = .013).

The results showed no appreciable difference in mean spherical equivalent and astigmatism between the PK and lamellar keratoplasty eyes. However, the lamellar keratoplasty eyes had a markedly lower incidence of complications than the PK eyes. Complications included allograft rejection and glaucoma.

The PK and modified lamellar keratoplasty eyes had a 100% graft survival rate at 3 years postop; the manual lamellar keratoplasty eyes had a mean graft survival rate of 73%.

"[Modified Anwar technique deep anterior lamellar keratoplasty] is emerging as a preferred choice among the lamellar techniques for better optical outcome," the authors said. "Further studies are required to provide long-term analysis of these results."

This study showed that DALK, when performed with a big bubble technique to effect total stromal removal, provided visual outcomes equivalent to PK, with fewer postoperative complications. With DALK, recipient endothelium is retained so patients can taper off corticosteroids earlier without risk of endothelial rejection. Less steroid exposure reduces the risk of developing cataracts or glaucoma and speeds the healing process so that sutures can be removed sooner. Although descemetic DALK is a more challenging procedure than PK, the authors suggest some modifications to achieve a big bubble in a more predictable manner. This study joins a growing body of evidence that DALK is better than PK over the long run, particularly for young keratoconus patients who would like their graft to survive a lifetime.

– Marianne O. Price, PhD
Executive Director, Cornea Research Foundation of America, Indianapolis