Laser in Situ Keratomileusis Outcomes With Ablation Centration on Coaxially Sighted Corneal Light Reflex
Narrative Responses:
Purpose
Decentration of Excimer laser ablation can induce cylinder and coma. Two standard refractive platforms, at different locations with similar demographics were compared for pre and post-operative cylinder. One location had a Zyoptix Technolas 217z laser (Technolas) and the second location used a VISX STAR S4 (Visx)
Methods
Ablations were centered over the coaxially sighted corneal light reflex. The Technolas Advanced Planoscan 6.5MM optical zone was used with Iris registration and Advanced Control Eyetracking (real time tracking of the iris rotation). The x and y positions were adjusted by the surgeon just before the ablation. A Visx Standard 6.5 mm optical zone with 8.0 mm blend zone was used. The ActiveTrak real time pupil tracker was used with the x and y “Offset “position set by the surgeon before making the LASIK flap. The reticle was used to estimate the offset, limited to 0.35mm by the laser.
Results
Data at one month postop was available for 137 eyes for the Technolas and 195 eyes for the Visx. Uncorrected visual acuities at one month for 20/20 and 20/25 with the:Technolas 82% and 93%; Visx 87% and 96%. Pre-op the average/standard deviation of sphere and cylinder were: Technolas -3.74 +/- 2.23 and-0.96+/-0.99; Visx -3.21+/-1.52 and -0.86 +/- 0.71. At one month post op the average /standard deviation of the sphere and cylinder were: Technolas -0.02/0.40 and -0.24+/-0.25;Visx -0.07/0.23 and -0.23/0.21. Both pre-op and at one month post -op, there was no statistical difference between the Technolas and Visx cylinder,.
Conclusion
Treatments in both cases were based on manifest refraction, optimized ablation profiles with treatments centered over the coaxially sighted corneal light reflex. Similar outcomes were obtained with the two laser platforms used.