Topography-wavefront ablations offer solutions

Dr. Reinstein, of the London Vision Clinic, London, England, showed four examples from a study of 15 eyes of 11 patients who were treated using the Mel-80 excimer laser with the new CRS-Master II (Carl Zeiss Meditec) ablation profile generator. Topography was obtained using the Atlas 995 topographer (Carl Zeiss Meditec) and wavefront sensing was performed with the high-resolution WASCA aberrometer (Carl Zeiss Meditec). In the cases that were re-treated with LASIK, the Artemis VHF digital ultrasound (Ultralink LLC) was used for determining adequate residual stromal thickness reserves.

In another case, the patient had a plano refraction but night-vision disturbances from a decentered ablation produced by an Alcon LADARVision LASIK procedure 8 years before. At 6 months after the PRK CRS-Master II re-treatment, the patient's uncorrected visual acuity (UCVA) improved from 20/20 to 20/16 and higher-order aberrations were significantly reduced. Seidel coma dropped from 4.49 μm preoperatively to 2.81 μm postoperatively. Seidel spherical aberration also dropped from –7.71 to –3.13 μm after PRK. The high-order RMS value was reduced from 0.88 to 0.50 μm.

A patient who had undergone RK exhibited inferior steepening, possibly because of asymmetric depth of incisions. One week after a CRS-Master II PRK re-treatment, Seidel spherical aberration was almost gone (–0.14 μm) compared with preoperatively at –11.81 μm. Higher-order RMS was reduced from 0.95 to 0.68 μm, he reported.