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Manual Top Hat Wound Configuration for Penetrating Keratoplasty

Bahar, Irit MD; Kaiserman, Igor MD, MSc, MHA; Srinivasan, Sathish FRCSEd, FRCOphth; Berger, Yoav MD; McAllum, Penny MBChB, FRANZCO; Slomovic, Allan MA, MD, FRCS(C); Rootman, David MD, FRCS(C)

doi: 10.1097/ICO.0b013e3181609300
Clinical Science

Purpose: To compare the outcomes of manual top hat penetrating keratoplasty (PK) versus traditional PK.

Methods: We reviewed the charts of 71 consecutive patients who underwent manual top hat (n = 36) or traditional (n = 35) PK at our institute. Main outcome measures included best-corrected Snellen visual acuity (BCVA), topographic and refractive results, high-order ocular aberrations, endothelial cell counts, and complication rate.

Results: No difference in mean BCVA between the 2 groups was noted after 12 months of follow-up. The mean spherical equivalent power was mild myopia, and the mean astigmatism was <4.2 D cylinder in both groups. There was no difference in total high-order aberrations, except spherical aberrations: 0.88 ± 0.74 μm in the top hat versus 0.49 ± 0.41 μm in the traditional PK (P = 0.01). Endothelial cell count was significantly higher in top hat PK group (1978 ± 277 vs. 1449 ± 516/mm2 in traditional PK; P < 0.0001), and time to all suture removal was shorter (3.9 ± 1.5 vs. 9.7 ± 1.1 months in traditional PK; P < 0.0001).

Conclusions: BCVA and refractive results are similar after manual top hat and traditional PK. Top hat PK speeds up suture removal and contributes to higher endothelial cell counts in the grafts 1 year after surgery.

Author Information

From the Ophthalmology Department, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada.

Received for publication August 27, 2007; revision received October 15, 2007; accepted October 20, 2007.

Reprints: Irit Bahar, Department of Ophthalmology, Toronto Western Hospital, 399 Bathurst Street, Ontario, Canada M5T2S8 (e-mail:

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