Topographic- and Wavefront-guided Customized Ablations With the NIDEK-EC5000CXII in LASIK for Myopia

Abstract

PURPOSE: To assess refractive outcomes, changes in the total higher order root mean square (RMS) aberration, and changes in higher order wavefront aberrations after LASIK for myopia and myopic astigmatism with the NIDEK Advanced Vision Excimer Laser platform (NAVEX) using either an aspheric or topography-based or whole eye wavefront ablation algorithm. METHODS: This was a retrospective study of 1459 eyes that underwent LASIK for myopia and myopic astigmatism. The mean preoperative spherical equivalent refraction was -4.68 diopters (D) (range: -0.50 to -9.63 D) with astigmatism up to -4.50 D. Treatments were classified into three categories depending on the type of ablation algorithm used - optimized aspheric transition zone (OATz) denoted eyes that underwent aspheric treatment zones; customized aspheric treatment zone (CATz) denoted eyes that underwent customized ablations based on corneal topography; and OPDCAT denoted eyes that underwent customized ablation based on the whole eye wavefront profile. Follow-up data are reported at 3 months (69%) and 12 months (17%) postoperatively. RESULTS: Three months after LASIK, the predictability (±0.5 D from target refraction) was 80% for OATz, 91% for CATz, and 76% for OPDCAT. Of all eyes, 96% were within ±1.0 D of intended refraction 3 months postoperatively and 100% after 12 months (87% ±0.5 D). In the aspheric and custom groups, a notable improvement of uncorrected visual acuity was noted between 3 and 12 months after LASIK. No eye lost >1 line of best spectacle-corrected visual acuity. Mean higher order RMS increased in all groups. CONCLUSIONS: The data support that the treatment of myopia and myopic astigmatism is safe and effective with NAVEX. Customized ablation based on corneal topography rather than on total wavefront error was more predictable. [J Refract Surg. 2006;22:754-763.]

Clinical outcomes of optimized prolate ablation and custom aspheric treatment in laser-assisted subepithelial keratectomy

“…12,[17][18][19] One study 20 found that the OPDCAT algorithm induces fewer ocular HOAs than customized aspheric transition zone (CATz) ablation based on corneal topography. However, other studies 21,22 found CATz to be more predictable and to induce less aberration than OPD-CAT. There is no conclusive evidence that 1 algorithm provides better refractive outcomes.…”

Efficacy of laser in situ keratomileusis in correcting anterior and non-anterior corneal astigmatism: Comparative study

“…Our study is unique in that it differentiates the efficacy of astigmatic correction based on the location of the astigmatism on the visual axis and derives an index of success for each type. Several studies have assessed the effectiveness of correcting HOAs measured by wavefront and the secondary impact on anterior corneal astigmatism [10][11][12][13][14][15][16] ; however, to our knowledge, ours is the only study to assess the effect of treating only LOAs on the anterior cornea and the relationship between the treatment's efficacy and the origin and location of the astigmatism preoperatively. The results are equally relevant to wavefrontguided treatments.…”

“…Considerable progress has been made in recent years in developing topographicguided technology designed to treat corneal aberrations at their sourcedthe cornea 13 das well as a hybrid approach combining topographic-guided treatment with wavefront-guided treatment. [9][10][11][13][14][15][16][17][18][19] Although it is now commonly accepted that topographyguided treatment should be considered in eyes with irregular corneal astigmatism (higher-order aberrations [HOAs]), the importance of detecting the location of regular astigmatism (lower-order aberration [LOA]) preoperatively in planning routine laser-vision correction treatment is often overlooked.…”

Effect of excimer laser repetition rate on outcomes after photorefractive keratectomy

“…Improvements in excimer laser technology have led to reproducible and safe results. The improvements include the introduction of highly sophisticated tracking systems, 1 a decreased laser-beam spot size, 2 linking of laser platforms with topography and wavefront analyzer systems, 3 and an increased repetition rate. 4 Photorefractive keratectomy (PRK) was the first widely used refractive procedure.…”