Half top hat wound configuration for penetrating keratoplasty: 1-year results

To compare the 1-year outcomes after half-top-hat (HTH) penetrating keratoplasty (PK) versus top-hat (TH) PK and regular PK.

We reviewed the clinical notes of 87 consecutive patients who had undergone either HTH PK (23 eyes), TH PK (36 eyes) or regular PK (35 eyes) at Toronto Western Hospital between 2002 and 2007. We evaluated best-corrected visual acuity (BCVA), topographic and refractive results, high-order ocular aberrations, endothelial cell counts and complication rates.

The three groups of patients did not differ significantly in their demographics (age, gender and laterality), donor endothelial cell counts, preoperative visual acuity or intraocular pressure (IOP). At 12 months postoperatively, BCVA was similar in the three groups, as was the mean spherical equivalent and cylinder. The time to sutures removal was significantly shorter in the HTH PK versus regular PK groups (3.8 (1.2) vs 9.7 (1.1) months, p<0.0001), and the endothelial cell counts were significantly higher (p = 0.003). The IOP was higher in the HTH PK patients than in regular PK patients (p = 0.04). All high-order aberrations tested were significantly higher in the HTH PK than in the regular PK groups (p<0.01). Regular PK had a higher rate of astigmatism treated with relaxing incisions (n = 7 vs n = 2 in HTH PK) and dehiscence of wound incision (n = 2, versus n = 0 in HTH PK).

BCVA and refractive results are similar after half-top-hat, top-hat and regular PK. Half-top-hat PK substantially speeds up visual recovery and contributes to significantly higher endothelial cell counts in the grafts 1 year after surgery.