PALK offers precise stromal bed thickness

Issue: May 10, 2009

SAN FRANCISCO — A keratoplasty procedure featuring pachymetry-guided ablation offers individualized treatment, low complication rates and positive visual outcomes, two of the procedure's pioneering surgeons said here.

Maria Clara Arbelaez

Cesar Carriazo

Maria Clara Arbelaez, MD, and Cesar Carriazo, MD, discussed pachymetry assisted laser keratoplasty (PALK) during a symposium sponsored by Schwind at the American Society of Cataract and Refractive Surgery here. PALK is performed with the company's Amaris excimer laser.

"We've become excited to see how a lamellar procedure . . . can be so easy and precise, and we have the technology available," Dr. Arbelaez said.

A pachymetry map is generated with the Galilei Dual Scheimpflug Analyzer (Ziemer) with eye tracking, Dr. Arbelaez said. An ablation profile is created, allowing for residual stromal bed thickness of 100 µm.

The Amaris laser is used to ablate the recipient stromal bed, which typically takes about 3 minutes. Precise ablation provides a uniform residual stromal thickness to provide a perfect match for the donor button, Dr. Arbelaez said.

Indications for PALK include keratoconus with no central opacity and post-LASIK ectasia. Contraindications include collagen vascular disease, autoimmune disease, herpes, blepharitis and severe eye disease, Dr. Carriazo said.

This is a very interesting new procedure that appears to be an advance over just doing phototherapeutic keratectomy with masking agents. However, the devil may be in the details. We will have to see how it compares to either the big bubble technique or hand dissections for deep anterior lamellar grafts. Leaving 100 µm in the bed is about as thick as one would want to leave and still be able to get good visual results on a routine basis. I look forward to finding out more about this procedure.

– Francis W. Price Jr., MD
OSN Cornea/External Disease Board Member