Bowman’s layer transplantation shows promise for keratoconus

Issue: May 25, 2015

SAN DIEGO — Bowman’s layer transplantation reduced or stabilized corneal ectasia in eyes with keratoconus that were not eligible for corneal collagen cross-linking or intracorneal ring segments, according to a study presented here.

Perspective from Mark A. Terry, MD

“Historically, the treatment of keratoconus was limited to fitting contact lenses for as long as possible . . . and the patient was normally referred for a PK or [deep anterior lamellar keratoplasty],” Korine Van Dijk, said at World Cornea Congress. “What has been lacking so far is a way to arrest ectasia.”

The technique involves making a scleral tunnel and a mid-stromal pocket. A stained donor Bowman’s layer is positioned onto a glide and inserted into the pocket, unrolled and stretched to the periphery of the cornea, Van Dijk said.

The study included 22 eyes of 19 patients with a mean age of 32 years. Mean preoperative corneal thickness was 332 m.

Mean follow-up was 21 months, and follow-up ranged up to 36 months.

Investigators evaluated complications, endothelial cell density, corneal tomography and best corrected visual acuity.

Intraoperative Descemet’s membrane perforation occurred in two eyes. However, no postoperative complications were reported.

Endothelial cell density and best corrected visual acuity did not change from before surgery to after surgery, Van Dijk said.

“This may indicate that potential candidates for Bowman’s layer transplantation should present with subjectively acceptable vision with their contact lenses,” Van Dijk said. “For these kinds of keratoconus cases, Bowman’s layer transplantation may effectively reduce and stabilize the ectasia, keeping these eyes in their contact lenses with a relatively low risk of complications, and so postpone a potential PK or DALK.”

Corneal flattening occurred after surgery and remained stable for up to 2 years, Van Dijk said. - by Matt Hasson

Disclosure: Van Dijk reports no relevant financial disclosures.

Perspective

Mark A. Terry, MD

Van Dijk and the Melles group have explored the effect of a novel surgical treatment for advanced keratoconus by placing donor Bowman’s layer into a hand-dissected mid-stromal pocket. While the lack of ectatic progression of the treated eyes is promising, what is missing is an adequate physiologic explanation of why the treatment would work. There is no randomized control of making a pocket without a Bowman’s transplant to see if it is simply the pocket that is having an effect. If the transplanted Bowman’s layer is needed, is it simply a space-occupying tissue and would any porous material or tissue placed in the pocket work?

While those of us who did DLEK surgery years ago are adept at making limbus-to-limbus mid-stromal pockets by hand, if this surgery is to become commonly performed, the femtosecond laser will likely play a role in increasing the simplicity and safety of the procedure. The Netherlands group is once again at the forefront of innovative surgical design for a common disease, but much more work needs to be done.

Mark A. Terry, MD

Director, Corneal Services, Devers Eye Institute, Portland, Ore.

Disclosures: Terry reports no relevant financial disclosures.