Half top-hat incision for PK heals faster than regular incision

Br J Ophthalmol. 2009;93(12):1629-1633.

The half top-hat, top-hat and conventional incision designs for penetrating keratoplasty yielded similar visual and refractive outcomes, according to a study.

However, the half top-hat incision proved safer than the other incision designs, the authors said.

"Half top-hat PK substantially speeds up visual recovery and contributes to significantly higher endothelial cell counts in the grafts 1 year after surgery," they said.

The retrospective study included 94 eyes of 87 patients; 23 eyes underwent half top-hat PK, 36 eyes underwent top-hat PK and 35 eyes underwent regular incision PK. The three groups were similar in age, gender, bilateral or unilateral surgery, donor endothelial cell count, preoperative visual acuity and IOP.

Investigators evaluated best corrected visual acuity, topography, refraction, higher-order aberrations, endothelial cell counts and complications.

At 12 months after surgery, the three groups had similar BCVA, mean spherical equivalent and cylinder. However, sutures were removed at a mean 3.8 months after surgery in the half top-hat incision group and after 9.7 months in the regular PK incision group. The difference was statistically significant (P < .0001).

The half top-hat group had markedly higher endothelial cell counts (P = .003), IOP (P = .04) and high-order aberrations (P < .01) than the regular incision group.

Seven eyes in the regular incision group and two eyes in the half top-hat group had astigmatism treated with relaxing incisions. Two eyes in the regular incision group and no eyes in the half top-hat group experienced wound dehiscence, the authors said.