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Nicholas Nissirios, Henry D. Perry, Eric Donnenfeld, Erfan Nadji; Astigmatism Correction Post Penetrating Keratoplasty (PK) Using a Femtosecond Laser System (LensX). Invest. Ophthalmol. Vis. Sci. 2012;53(14):1503.
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To evaluate the efficacy and safety of astigmatism correction post PK of a newly developed femtosecond laser system (LensX)
This is a retrospective case series study. We reviewed charts of patients with high corneal astigmatism post PK causing visual impairment. The patients were treated with a femtosecond laser (Lensx by Alcon) for astigmatism correction between 9/2011 and 11/2011. Pre-operatively evaluation included a complete eye exam, corneal topography, pachymetry, Schirmer’s test, tear osmolarity and slit-lamp photography. A pair of relaxing arcuate incisions were created on the steep corneal meridian as defined by a topographic map. For less than 4D of astigmatism two 40 degree incisions were performed, for 4-6D two 50 degree and for more than 6D two 60 degree incisions were made. Using the femtosecond laser, under topical anesthesia the pair of arcuate incisions was performed within the corneal graft at a diameter of 6.5mm and depth of 85% of the graft thickness measured by intraoperative OCT (incorporated in the laser system). We evaluated the efficacy of the laser in reducing corneal astigmatism and improving visual acuity. Possible adverse events of the treatment were noted. The effect of age, gender, cause of PK towards the final outcome were also evaluated. Follow up visits were at post-op day#1, week#1, month#1
14 patients were included in the study, 6 male and 8 female (mean age 66±15 years). Mean subjective astigmatism was 9.59D (±2.8D) preoperatively. On the first day after the treatment the mean subjective astigmatism was 5.3D(±1.7D, P=0.0005) with average reduction of 44% and on week 1 post treatment 4D(±1.25D, P=0.0001) average reduction of 52.5%. Best spectacle corrected visual acuity (BSCVA, logMAR) preoperatively was 0.67(±0.23), on day 1 post surgery 0.51(±0.33, P=0.025) and week 1 0.49(±0.33, P=0.016). Age, gender and etiology of PK had no effect on final outcome. The only adverse finding was mild worsening of the dry eye symptoms observed in 6 patients in the immediate postoperative period. No infections or other post-operative complications were noted
The Lensx femtosecond laser system has been approved recently for the treatment of astigmatism using arcuate corneal incisions. The incisions are reproducible and precise. Its use on treating astigmatism post PK has not been evaluated previously. Arcuate incisions with the Lensx femtosecond laser system are an effective and safe way of treating high astigmatism in patients with post penetrating keratoplasty astigmatism. We hope that as we increase our experience with this technique we will be able to develop a precise nomogram and predictable algorithm for optimal surgical outcomes
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