Reduction of spherical aberration with the Nidek NAVEX customized ablation system

PURPOSE: Spherical aberration is the most frequent optical aberration induced by refractive surgery, reducing visual acuity and causing halos. We present preliminary results of Custom Ablation Transition Zone (CATz), which we developed for Nidek's Final Fit software, part of the Nidek NAVEX customized ablation system. METHODS: We studied 55 eyes of 51 patients (31 males, 20 females) who underwent refractive surgery. Mean preoperative spherical equivalent refraction was -5.50 +/- 3.30 D (range -12.00 to +4.50 D). Mean age was 35 years (range 23 to 47 yr). All patients underwent complete preoperative ophthalmologic examination, including aberrometry and topography, then surgery with laser epithelial keratomileusis, and OPD-based refractive treatment with the Nidek EC-5000 excimer laser. The Nidek Final Fit software with the CATz feature was always used. Postoperatively, all patients repeated the ophthalmologic examination inclusive of aberrometry at day 30, 60, and 90. RESULTS: The 3-month follow-up rate was 21.8%. Mean postoperative spherical equivalent refraction was -0.33 +/- 0.91 D (range -0.75 to +0.75 D), with a mean sphere of -0.23 +/- 0.78 D (range -2.50 to +0.75 D) and a mean cylinder of -0.21 +/- 0.33 (range -1.00 to 0 D). At 3 months, 43% of eyes achieved 20/15 or better UCVA, and 43% achieved 20/20 or better UCVA; 63% achieved 20/15 or better BSCVA and 25% achieved 20/20 or better BSCVA. Postoperative spherical aberration was unchanged for a 3-mm pupil. CONCLUSION: Customized ablation with the Nidek NAVEX system provided excellent refractive results. The CATz algorithm of the Nidek Final Fit software appeared to prevent induction of spherical aberration.