Femtosecond Laser Arcuate Keratotomy for the Correction of High Astigmatism after Keratoplasty
Received 20 March 2008; received in revised form 8 January 2009; accepted 13 January 2009. published online 23 April 2009.
Purpose
To determine the feasibility and initial outcomes of using a femtosecond laser to perform arcuate keratotomies to correct high post-keratoplasty astigmatism.
Design
Prospective noncomparative interventional case series.
Participants
Twelve eyes of 12 consecutive patients (mean age 44.9±9.5 years) who presented with a high degree of astigmatism, noncorrectable with spectacles or contact lenses (10 post-penetrating keratoplasty, 2 post-deep lamellar keratoplasty), and were candidates for relaxing incisional corneal surgery.
Methods
The Femtec (20/10 Perfect Vision, GmbH, Heidelberg, Germany) femtosecond laser performed paired 90-degree angled arcuate incisions on the graft button. The incision sites and depths were programmed at 1.00 mm inside the graft edge and at 90% of the corresponding local graft thickness, whereas the angular lengths of the cuts were determined by analyzing the locations and extents of the steepest meridians in the topographic map.
Main Outcome Measures
Changes in uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), mean subjective and topographically determined astigmatism; imaging of incisions by anterior segment optical coherence tomography (AS-OCT); and wound healing by in vivo confocal microscopy (IVCM).
Results
Postoperative follow-up extended to 6 months. Mean uncorrected logarithm of the minimum angle of resolution (logMAR) BSCVA and UCVA improved from preoperative values of 0.25±0.16 and 1.05±0.18 to 6-month values of 0.11±0.12 (standard deviation) and 0.55±0.34, respectively (P<0.05). Mean subjective astigmatism was 7.16±3.07 diopters (D) preoperatively and 2.23±1.55 D at 1 month after surgery (P = 0.002) and remained stable to the end of follow-up. Anterior segment optical coherence tomography image analysis showed that the depth and location of the incisions were consistent with the preoperative surgical plan. In vivo confocal microscopy showed mild edema and keratocyte activation along the incision edges, together with initial epithelial ingrowth inside the wound, followed by subsequent moderate fibrotic scarring.
Conclusions
Arcuate keratotomies performed with the femtosecond laser were effective in reducing post-keratoplasty astigmatism. Laser-generated incisions within the graft button presented precise geometry and reliable depth of incision, with a wound healing pattern characterized by epithelial ingrowth and mild fibrosis.
Financial Disclosure(s)
The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Available online: April 23, 2009.
Department of Medicine and Ageing Science, Ophthalmic Clinic, University “G. D'Annunzio” of Chieti and Pescara, Italy
Correspondence: Mario Nubile, MD, Via Valleparo, 8, 6610 Torrevecchia T. (Chieti), Italy
Manuscript no. 2008-371.
Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
ABSTRACT