Manual top hat PK slightly more advantageous than traditional PK, researchers find

Best corrected visual acuity and refractive outcomes appear similar with the manual top hat penetrating keratoplasty technique and the traditional penetrating keratoplasty technique, according to a study by researchers in Canada.

"Top hat PK speeds up suture removal and contributes to higher endothelial cell counts in the grafts 1 year after surgery," the authors said.

Irit Bahar, MD, and colleagues reviewed the charts of 71 consecutive patients who underwent either manual top hat PK or traditional PK. The researchers compared BCVA, topographic and refractive results, high-order aberrations, endothelial cell counts and complication rates in the two groups. Specifically, 36 patients received the manual top hat procedure and 35 patients underwent traditional PK.

At 12 months' follow-up, the researchers found no significant difference in mean BCVA between the two groups. The mean spherical equivalent power was mild myopia, and astigmatism averaged less than 4.2 D of cylinder in both groups, according to the study.

No differences in total high-order aberrations were found, except for spherical aberrations; top hat PK measured a mean 0.88 µm while traditional PK measured a mean 0.49 µm (P = .01). Endothelial cell counts were significantly higher in the top hat PK group (P < .0001).

Additionally, the length of time before suture removal was shorter in the top hat PK group (P < .0001), according to the study, published in the June issue of Cornea.