Abstract
Purpose: :
To evaluate a new approach to the intraoperative management of astigmatism in penetrating keratoplasty (PKP).
Methods: :
165 eyes were enrolled between 2001 and 2004 in this prospective, non–randomized single–center study. 79% were keratoconus eyes, 5% post–LASIK ectasia, and the rest included bullous keratopathy and various dystrophies. A specially–designed marker was used to outline a 24–bite single running 10–0 nylon suture. Recipient cornea trephination diameters ranged from 7.0 mm to 8.75 mm, and donor button diameters were between 0.25 mm and 0.5 mm larger. The Hanna corneal trephine system was used. At the end of the procedure the cornea was lubricated with 0.25% sodium hyaluronate, and with the patient still in the prone position, an intraoperative topographer was used to generate a corneal map. The suture was adjusted and intraoperative topography was repeated until an astigmatism ≤ 2.0D was obtained. Postoperative topical treatment included dexamethasone and tobramycine in the first month, and fluorometholone thereafter. In eyes in which >3.0D of astigmatism was noted at 1 month (26%), suture adjustment was performed, using the same intraoperative topographer.
Results: :
At 12 months (suture in), with data from 64.5% of the eyes available, the mean refractive astigmatism was 3.53D (±2.32). At 18 months (suture out), with data from 19.4% available, the mean refractive astigmatism was 3.53D (±2.35D), with the mean topographic astigmatism almost identical at both follow–up examinations. Analysis of the 19.4% suture–out eyes examined at 18 months showed that mean refractive astigmatism varied by 0.95D between the 1–month and 18–month gates, and that mean topographic astigmatism varied by 0.05D in the same period. Suture removal (12– vs 18–month data) resulted in a mean refractive astigmatism change of 0.20D and mean topographic astigmatism change of 0.70D (p<0.05) in this group of eyes.
Conclusions: :
This study indicates that intraoperative topography–guided astigmatism control provides an effective strategy for achieving low postoperative astigmatism in PKP eyes. It also results in early astigmatism stability, which in turn makes possible a very fast visual rehabilitation with a quicker return to the workplace.
Keywords: cornea: clinical science • refractive surgery • astigmatism