Oversized grafts linked to near-normal corneal biomechanics after PK for keratoconus

Issue: November 10, 2012

Larger corneal graft size appeared to correlate with near-normal postoperative biomechanical properties in eyes undergoing penetrating keratoplasty for keratoconus, a study found.

“Graft biomechanics after [penetrating keratoplasty] in keratoconic eyes seem to be closer to normal values by using a large oversized donor, probably yielding more stable postoperative refraction and more predictable results after graft refractive surgery,” the study authors said. “This speculation can be the objective for future studies. Additionally, graft biometrics seems to play a more important role in postoperative IOP readings than anatomical features.”

The cross-sectional study included 34 eyes of 34 patients with keratoconus who underwent PK. Mean patient age was 29.6 years. Visual, anatomic and corneal biomechanical properties were assessed at least 6 months after complete suture removal. Mean follow-up was 82.4 months.

The Ocular Response Analyzer (Reichert) was used to measure corneal hysteresis, corneal resistance factor and corneal-compensated IOP (IOPcc).

Adjusted data showed that corneal hysteresis correlated significantly with donor trephine size (P = .028) and central graft thickness (P = .025). Corneal resistance factor also correlated strongly with donor trephine size (P = .012) and central graft thickness (P = .001).

Goldmann applanation tonometry IOP demonstrated a strong relationship with corneal hysteresis (P = .014), corneal resistance factor (P = .012) and corneal-compensated IOP (P = .024). Data showed no significant correlation between Goldmann applanation tonometry IOP and central graft thickness, mean keratometry or donor trephine size, the authors said.

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Source:

Cornea. 2012;31(8):855-858.