Wavefront-guided LASIK helpful tool for residual myopia

Dr. Wang, chief resident at Stanford University, Stanford, CA, and colleague Edward Manche, MD, conducted a retrospective study in which they evaluated the CustomVue system and the effects of higher-order root mean square (RMS) values preoperatively and postoperatively.

Dr. Manche performed all surgeries using the VISX S4 excimer laser (VISX/ AMO) to treat patients who had previously undergone LASIK.

The mean preoperative spherical equivalent was –0.79 ± 0.50 D (range, –2.37 to 0.75 D). Three months after the enhancement surgery, the spherical equivalent decreased to –0.31 ± 0.36 D (range, –0.875 to +0.75 D), Dr. Wang reported.

No complications occurred. Of the 59 eyes, 57 eyes had been followed for 1 month and 31 eyes had 3 months of follow-up.

As expected, there was a decrease in the amount of myopia at 1 and 3 months postoperatively, with no significant difference between the two time points, Dr. Wang pointed out.

"The efficacy of the procedure was excellent; at 3 months postoperatively, 81% of eyes had 20/20 or better uncorrected visual acuity (UCVA) and 32% of eyes had 20/16 or better UCVA," Dr. Wang said. "The predictability was also excellent. All eyes were within 1 D of the target correction at the 3-month examination, and 81% of the eyes were within 0.5 D of the attempted correction at 3 months."

No eyes lost more than one line of best-corrected visual acuity (BCVA). Most eyes gained lines of BCVA 1 and 3 months after the enhancement procedure.

The analysis of higher-order aberrations showed that there was a decrease in the preoperative RMS from 0.39 ± 0.18 μm (range, 0.14 to 0.97 μm) to 0.35 ± 0.16 μm (range, 0.07 to 0.74 μm) 3 months after the enhancement. A reduction in coma was also observed from 0.22 μm preoperatively to 0.18 μm at the 3-month visit. The trefoil values were similar preoperatively and postoperatively at 0.13 μm and 0.12 μm, respectively. The spherical aberration decreased from 0.19 D preoperatively to 0.14 D at 3 months. No complications developed intraoperatively or postoperatively and there were no cases of epithelial ingrowth.

"Our results showed that the VISX CustomVue wavefront-guided re-treatment using Fourier-based treatment software in eyes that had undergone a previous LASIK procedure is effective, predictable, and safe for patients with residual myopia and compound myopic astigmatism," Dr. Wang said. "Analysis of higher-order RMS and aberrations showed a decreasing trend over time."

She noted, however, that longer follow-up is necessary to assess the stability of the refraction.