Comparison of a new implantable collamer lens formula to standards formulas using spectral domain optical coherence tomography.

PURPOSE: To use spectral-domain optical coherence tomography (SD-OCT) data to develop a new implantable collamer lens (ICL) sizing formula and compare vault outcomes with the Online Calculation and Ordering System™ (OCOS) and the NK2 formula. METHODS: Consecutive eyes (n = 237) were evaluated that had undergone ICL/toric ICL implantation. Actual ICL vaults were measured, and a what-if analysis was performed to predict vault values with the NK2 formula using SD-OCT data. To develop a new formula (EPB), multiple regression analysis was performed with different parameters than the NK2 formula. Predicted vaults with NK2 and EPB formulas were compared to the actual vaults. RESULTS: Parameters that were correlated with optimal ICL size were white-to-white, anterior chamber width, lens rise and desired refractive correction. The mean postoperative vault was 489 ± 258 µm. At last visit, 94.5% of eyes were within the manufacturer's acceptable vault range. Predicted vaults in the acceptable range were 74 and 87% with the NK2 and EPB formulas, respectively. Six percent had a predicted vault less than 100 µm with the EPB formula compared to 1% for actual outcomes. The NK2 formula resulted in a shift toward higher predicted vaults while the EPB formula was similar to the actual postoperative vaults but with slightly more cases with extremely low and high vaults. CONCLUSION: SD-OCT data with OCOS result in good postoperative vaults. Further refinement is required to the NK2 for use with SD-OCT data. Although the EPB formula provides acceptable predicted vaults, further refinement with a larger sample size is needed.

Transepithelial corneal crosslinking with oxygen enhancement and pulsed light for progressive ectasia: one-year results.

PURPOSE: To evaluate the efficacy and safety of transepithelial accelerated crosslinking (TE-ACXL) using pulsed light and supplemental oxygen. METHODS: Thirty eyes of 30 consecutive patients with progressive keratoconus or post-LASIK ectasia were enrolled in a prospective non-comparative study conducted at the Magrabi Eye Center (Jeddah, Saudi Arabia). All eyes underwent TE-ACXL with supplemental oxygen. Primary outcome measures were the mean change in corrected distance visual acuity (CDVA) (logMAR) and maximum keratometry (max K) from preoperatively to 12 months postoperatively. Secondary outcome measures included change in manifest refractive spherical equivalent (MRSE), refractive cylinder, keratometry, symmetry index (SI), center-surrounding index (CSI) and ectasia index (EI) of the anterior and posterior corneal surfaces, corneal and epithelial thickness at corneal vertex and thinnest location, corneal densitometry, corneal high order aberrations (HOA) and endothelial cell density (ECD). RESULTS: Mean age was 29.6 ± 8.2 years. At 1 year, the follow up rate was 93.3%. CDVA improved statistically significantly at 12 months (p = 0.027). Measures of corneal keratometry or pachymetry did not change significantly (p < 0.05). Postoperatively, a demarcation line was documented in 78.6% eyes at 1 month, and in 12 (42.9%) eyes at 12 months. The mean depth of the demarcation line was 341.9 ± 49.4 µm. Corneal densitometry increased significantly at 1- and 3-months (p < 0.05) and returned to normal levels at 6- and 12-months postoperatively. CONCLUSION: TE-ACXL with oxygen supplement is effective at halting the progression of corneal ectasia for at least 1 year and can be a refractive neutral procedure.

Clinical Outcomes After Phacoemulsification With Implantation of Trifocal and Toric Trifocal Intraocular Lenses.

PURPOSE: To evaluate the visual and refractive outcomes, visual quality, patient satisfaction, and spectacle independence after phacoemulsification with bilateral implantation of a diffractive trifocal intraocular lens (IOL). METHODS: The study sample comprised 36 consecutive patients (72 eyes). Twenty-three (64%) patients underwent refractive lens exchange and 13 (36%) underwent cataract surgery. Exclusion criteria included previous ocular surgery, corneal higher order aberrations of greater than 0.4 µm, angle kappa of greater than 0.6 mm, and corneal astigmatism of greater than 5.00 diopters (D). All eyes were targeted for emmetropia. A toric IOL was used in 35 (48.6%%) eyes with corneal astigmatism of greater than 1.00 D. Uncorrected distance visual acuity (UDVA) and distance-corrected visual acuity were measured at 4 m and 80 and 40 cm. Patients underwent routine ophthalmic examination for 6 months postoperatively. Patient satisfaction was assessed with a subjective questionnaire at 6 months postoperatively. A P value of less than .05 was statistically significant. RESULTS: At 6 months postoperatively, the mean manifest refractive spherical equivalent was -0.01 ± 0.51 D. Binocular UDVA at 4 m and 80 and 40 cm was -0.02 ± 0.10, -0.07 ± 0.11, and 0.08 ± 0.10 logMAR, respectively. Binocular defocus curves presented two peaks of -0.07 and -0.02 logMAR for 0.00 and -2.00 D defocus, respectively. The Objective Scatter Index score decreased significantly in the cataract group and increased significantly in the refractive lens exchange group (P < .05, both cases). All patients were satisfied or very satisfied with the postoperative outcome. CONCLUSIONS: Bilateral implantation of a diffractive trifocal IOL resulted in good visual performance at all distances with high patient satisfaction and spectacle independence at 6 months postoperatively. [J Refract Surg. 2021;37(6):372-379.].

A contralateral, randomized comparison of optimized prolate ablation and conventional LASIK for myopia with the NIDEK excimer laser platform.

PURPOSE: To compare the refractive, visual acuity, topographic, and spherical aberration outcomes of LASIK using the Quest excimer laser platform with the optimized prolate ablation (OPA) profile (NIDEK Co Ltd) in one eye and conventional ablation profile in the fellow eye of the same patient. METHODS: Thirty-seven myopic patients underwent LASIK bilaterally, with one eye randomized to receive OPA ablation (-3.88±1.42 diopters [D], range: -1.53 to -7.50 D) and the fellow eye to receive conventional ablation (-3.89±1.37 D, range: -1.75 to -7.00 D). Independent and paired t tests were used for testing differences between groups at last postoperative follow-up (6 or 12 months). RESULTS: Postoperatively, 97% (32/33) of OPA eyes and 94% (31/33) of conventional eyes saw 20/20 or better without correction (P>.05). No eyes lost 2 or more lines of distance corrected visual acuity. Manifest refraction spherical equivalent was -0.16 D in the OPA group and -0.05 D in the conventional group (P>.05). Ocular spherical aberration was -0.003 µm in the OPA group and +0.102 µm in the conventional group (P<.05). Corneal asphericity was statistically lower after OPA (0.07±0.26) compared to conventional ablation (0.30±0.26) (P<.001). The mean programmed optical zone and achieved postoperative horizontal diameter of the effective optical zone were statistically significantly larger in the OPA group (P<.05). CONCLUSIONS: Postoperative visual acuity and refractive outcomes were similar between groups. Laser in situ keratomileusis using the OPA profile for the correction of myopia induced significantly less corneal and ocular spherical aberration, resulted in normal postoperative asphericity in 94% of eyes, and larger horizontal diameter of the effective optical zone compared to the conventional profile.

Prospective, randomized, double-blind, contralateral eye comparison of myopic LASIK with optimized aspheric or prolate ablations.

PURPOSE: To compare the postoperative outcomes of aspheric or prolate LASIK for myopia and myopic astigmatism. METHODS: In this double-blind, bilateral, randomized trial, 40 patients (80 eyes) with -0.75 to -7.00 diopters (D) of manifest refraction spherical equivalent (MRSE) underwent optimized aspheric treatment zone ablation (OATz group) in 1 eye and optimized prolate ablation (OPA group) in the fellow eye. Six-month postoperative outcomes were compared for MRSE and visual acuity, contrast sensitivity, patient satisfaction, ocular higher order aberrations (HOAs), and spherical aberration. The Wilcoxon signed rank test, Mann-Whitney U test, and paired t test were used for testing differences between groups. P<.05 was statistically significant. Main outcome measures included HOAs, spherical aberration, visual and refractive outcomes, and contrast sensitivity. RESULTS: Postoperatively, 36 patients (72 eyes) were evaluated. The MRSE was -0.07±0.23 D for the OPA group and +0.02±0.24 D for the OATz group (P>.05). Two (5%) eyes in the OPA group and 1 (3%) eye in the OATz group (P=.114) lost 1 line of corrected distance visual acuity. Postoperative visual acuity was not statistically different between groups (P>.05). Statistically lower change was noted in spherical aberration (0.011 µm) in the OPA group versus the OATz group (0.099 µm) (P<.001). Statistically higher induction of coma was noted in the OPA group (P=.035). No statistically significant differences were noted in photopic, mesopic, or glare contrast sensitivity and patient satisfaction between groups (P>.05, for all comparisons). CONCLUSIONS: The refractive and visual outcomes of OPA and OATz were equivalent. However, the postoperative optical quality of OPA-treated eyes was better.

Comparison of wavefront-guided aspheric laser in situ keratomileusis for myopia: coaxially sighted corneal-light-reflex versus line-of-sight centration.

PURPOSE: To compare refractive outcomes, higher-order aberrations (HOAs), and contrast sensitivity of myopic wavefront-guided aspheric laser in situ keratomileusis centered on the coaxially sighted corneal light reflex or on the line of sight. SETTING: Okamoto Eye Clinic, Ehime, Japan. DESIGN: Comparative case series. METHODS: Data at 3 months were compared based on the distance between the coaxially sighted corneal light reflex and the line of sight (P-distance) as follows: distance greater than 0.25 mm (high-distance group), distance greater than 0.15 mm and less than 0.25 mm (intermediate-distance group), and distance less than 0.15 mm (low distance group). RESULTS: The chart review included 317 eyes in the corneal-light-reflex group and 269 eyes in the line-of-sight group. The mean postoperative manifest refraction spherical equivalent was +0.123 diopter (D) ± 0.378 (SD) and +0.187 ± 0.480 D, respectively (P = .07). The safety and efficacy indices were significantly higher in the corneal-light-reflex group, including the high-distance subgroup and eyes with a P-distance less than 0.25 mm (P<.05, all cases). The HOAs (P<.001) and coma (P = .001) were significantly higher in the line-of-sight group (P<.001 and P = .001, respectively). The line-of-sight group had a significantly greater change in contrast sensitivity (P = .026). CONCLUSIONS: Centration on the coaxially sighted corneal light reflex resulted in better safety, effectiveness, and contrast sensitivity than line-of-sight centration. Centration on the coaxially sighted corneal light reflex was safer for myopic eyes with P-distances greater than 0.25 mm. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Comparison of corneal and total ocular aberrations before and after myopic LASIK.

PURPOSE: To assess the compensation of total ocular and corneal wavefront aberrations after conventional myopic LASIK. METHODS: This study comprised 57 eyes of 57 patients. Total and corneal aberrations were measured preoperatively and 3 months postoperatively using the OPD-Scan (NIDEK Co Ltd) aberrometer. Total and corneal aberrations root-mean-square (RMS) was calculated out to the 6th Zernike order for a 6.0-mm pupil diameter. The percentage increase postoperatively was defined by the ratio of RMS pre- and postoperatively for each corneal and total eye group. The compensation between corneal and internal aberrations for a given aberration group was defined as: (corneal aberration group RMS - total eye aberration group RMS)/corneal aberration group RMS. RESULTS: Postoperatively, higher order aberrations increased by a factor of 1.77+/-1.26 (total) and 2.47+/-2.25 (corneal) (P<.05). Coma aberration increased by a factor of 2.43+/-2.61 (total) and 2.56+/-2.66 (corneal). Spherical aberration increased by a factor of 1.46+/-1.83 (total) and 2.64+/-2.24 (corneal). The values of the ratio of compensation did not change significantly before and after LASIK for individual aberrations (P>.05). CONCLUSIONS: Although myopic LASIK induced significant corneal aberrations, the level of partial compensation of corneal aberrations by internal structures remained unchanged. These results suggest that the previously described emmetropization that is effective during development may also be effective with acquired variations in corneal shape.

Treatment of highly aberrated eyes using the NIDEK CXIII excimer laser.

PURPOSE: To describe the treatment of highly aberrated eyes due to previous excimer laser surgery or trauma. METHODS: Three eyes (three patients) with reduced visual quality due to previous decentration or corneal laceration (one eye) underwent topography-guided ablation using the CXIII excimer laser (NIDEK Co Ltd) to correct residual refractive error and/or wavefront aberrations. RESULTS: Postoperatively, one patient had a one-line increase in corrected distance visual acuity (CDVA) with a reduction in visual symptoms. At 2 months postoperatively, one patient maintained CDVA, increased uncorrected distance visual acuity from 20/20 to 20/15, and reported resolution of monocular diplopia. In all cases, the functional optical zone increased and wavefront aberrations decreased with selective flattening of the intended corneal region. CONCLUSIONS: Topography-guided ablation is an effective treatment of severe corneal aberrations due to surgery or trauma and can be selectively used to treat higher order aberrations with or without refractive error.

Customized aspheric treatment zone ablation to treat irregular corneas after corneal refractive surgery.

PURPOSE: To describe the retreatment of highly aberrated corneas due to previous keratorefractive surgery using topography-guided aspheric treatments. METHODS: Eight eyes (five patients) with reduced mesopic visual quality due to previous keratomileusis, excimer laser surgery, or radial keratotomy underwent retreatment with the customized aspheric treatment zone (CATz) algorithm with the CXIII excimer laser (NIDEK Co Ltd) to correct corneal wavefront aberrations. Before CATz treatments, all patients were satisfied with their preoperative photopic vision (all 20/30 or better uncorrected) yet were dissatisfied with their vision at night. All eyes had >20 microm (range: 20 to 33 microm) of corneal irregularity before CATz retreatment. All eyes had a flap cut or flap lift procedure for CATz retreatment. RESULTS: One year after treatment with CATz, no eyes lost best spectacle-corrected visual acuity (BSCVA); all eyes had BSCVA of 20/30 or better. Mean modulation transfer function increased by 13% by the end of the first postoperative year. A 0.45-microm decrease was noted in coma 1 year postoperatively. CONCLUSIONS: The CATz algorithm is effective in the treatment of severe corneal irregularities due to previous corneal surgery.

Comparison of myopic LASIK centered on the coaxially sighted corneal light reflex or line of sight.

PURPOSE: To compare refractive outcomes of myopic LASIK with centration on the coaxially sighted corneal light reflex (CSCLR) to centration on the center of the pupil (line of sight [LOS]). METHODS: The NIDEK CXIII excimer laser was used to treat 268 eyes with centration on the CSCLR (CSCLR group) and 288 eyes with centration on the LOS (LOS group). For the CSCLR group, the laser ablation was delivered 80% closer to the visual axis. One-month postoperative outcomes were compared. RESULTS: Preoperative manifest refraction spherical equivalent (MRSE) was -4.88+/-1.55 diopters (D) (range: -8.50 to -1.25 D) in the CSCLR group and -5.05+/-1.63 D (range: -9.75 to -1.50 D) in the LOS group. The postoperative MRSE was 0.17+/-0.39 D (range: -1.38 to -1.25 D) in the CSCLR group and 0.19+/-0.48 D (range: -1.63 to +1.88 D) in the LOS group. Safety (1.18) and efficacy (1.047) indices were statistically significantly higher in the CSCLR group compared to the LOS group (1.138 and 0.997, respectively) (P<.05). This trend was accentuated in a subgroup analysis of patients with >0.25-mm difference between the CSCLR and LOS, favoring the CSCLR group. A statistically significantly greater induction of higher order aberrations (P=.04) and coma (P<.01) was noted in the LOS group postoperatively. CONCLUSIONS: Myopic LASIK centered on the CSCLR was significantly safer and more effective than LASIK centered on the pupil (LOS), with significantly lower induction of coma and total higher order aberrations.

Total, corneal, and internal ocular optical aberrations in patients with keratoconus.

PURPOSE: To measure and compare total, corneal, and internal ocular aberrations using combined wavefront analysis and corneal topography in eyes with keratoconus and eyes with normal corneas. METHODS: This prospective study comprised eyes of patients with keratoconus and myopic patients seeking refractive surgery. Patients diagnosed with keratoconus and with a classification of "normal" or "keratoconus" on the NIDEK Corneal Navigator corneal disease screening software were selected for inclusion in this study. The normal group comprised eyes with a "normal" classification with 99% similarity. In the normal group, only one eye per patient was randomly selected based on a randomization schedule. Corneal, internal, and total wavefront measurements were provided by the NIDEK OPD-Scan II. RESULTS: One hundred eyes with keratoconus and 155 normal eyes were enrolled in the study. Statistically significant higher corneal and internal higher order aberrations were observed in the eyes with keratoconus (P<.05). However, an increase in ocular higher order aberrations proportional to corneal higher order aberrations was not observed in the keratoconus group. CONCLUSIONS: A compensatory effect of increased anterior corneal aberrations by internal aberrations in keratoconic eyes was present for some aberrations. The origin of this compensation and the optical mechanism behind it requires further study.

Photorefractive keratectomy for primary myopia using NIDEK topography-guided customized aspheric transition zone.

PURPOSE: To report the outcomes of topography-guided photorefractive keratectomy (PRK) for the treatment of myopia with or without astigmatism using the customized aspheric transition zone (CATz) ablation algorithm. METHODS: In this study, 335 eyes underwent PRK using the NIDEK Advanced Vision Excimer laser platform (NAVEX). Mean preoperative manifest refraction spherical equivalent was -4.42+/-3.46 diopters (D) (range: -14.50 to -0.50 D). Mean preoperative sphere was -3.94+/-3.43 D (range: -13.00 to -1.00 D), and mean preoperative cylinder was -0.96+/-1.05 D (range: -5.50 to 0.00 D). Refractive outcomes out to 1 year postoperatively were analyzed. RESULTS: At least 6 months postoperatively, all eyes maintained or gained lines of best spectacle-corrected visual acuity (BSCVA). There was a 51% increase in the eyes that read 20/16 or better uncorrected compared with preoperative BSCVA. At 1 year postoperative, 252/280 (90%) eyes had BSCVA 20/20 or better. Refractive outcomes within +/-0.50 D were observed in 223/275 (81%) eyes at 3 months, 228/300 (76%) eyes at 6 months, and 187/280 (67%) eyes at 1 year. CONCLUSIONS: Topography-guided PRK using CATz for the treatment of low, moderate, and high myopia is safe, effective, and predictable.

Outcomes of hyperopic LASIK with the NIDEK NAVEX platform centered on the visual axis or line of sight.

PURPOSE: To report refractive outcomes of hyperopic LASIK with automated centration on the visual axis compared with centration on the line of sight (LOS). METHODS: The NIDEK Advanced Vision Excimer Laser platform (NAVEX) was used to treat 181 hyperopic eyes with centration on the LOS (LOS group) and 64 hyperopic eyes with centration on the visual axis (visual axis group). The coordinates of the visual axis were digitally transferred to the excimer laser system based on the positional relationship between the LOS and the coaxially sighted corneal light reflex. All eyes were treated with a 6.5-mm optical zone and 9.0-mm transition zone. Three-month postoperative outcomes were retrospectively analyzed. RESULTS: The preoperative manifest refraction spherical equivalent (MRSE) was +2.57+/-1.26 diopters (D) (range: 0.13 to 5.63 D) in the visual axis group and +2.46+/-1.32 D (range: 0.38 to 5.63 D) in the LOS group. The postoperative MRSE was +0.29+/-0.70 D (range: -1.00 to 1.75 D) in the visual axis group and +0.19+/-0.57 D (range: -0.75 to 1.75 D) in the LOS group. Postoperatively, 81% (38/47) of eyes in the visual axis group and 64% (74/116) of eyes in the LOS group were +/-0.50 D. In the visual axis group, 91% (44/52) of eyes and 92% (102/109) of eyes in the LOS group maintained best spectacle-corrected visual acuity within one line compared with preoperatively. CONCLUSIONS: Initial experience with hyperopic LASIK centered on the visual axis indicated safe and predictable outcomes.

A retrospective comparison of LASIK outcomes for myopia and myopic astigmatism with conventional NIDEK versus wavefront-guided VISX and Alcon platforms.

UNLABELLED: POSE: To compare visual, refractive, and safety outcomes among a non-wavefront scanning-slit laser (NIDEK EC-5000) and wavefront-driven lasers (Alcon CustomCornea and VISX CustomVue). METHODS: A retrospective comparison of outcomes for 290 eyes that underwent LASIK for myopia and myopic astigmatism with either a conventional or custom ablation excimer laser system were compared. The preoperative refractive error and age of the patients were matched. Outcomes were tested for statistically significant differences among the conventional laser and each of the custom ablation lasers. A P value <.05 was considered statistically significant. Data with 3-month follow-up are reported. RESULTS: Postoperatively, mean manifest refraction spherical equivalent was -0.12+/-0.31 diopters (D) (range: -1.50 to 0.75 D) for the NIDEK group, -0.13+/-0.39 D (range: -1.88 to 0.75 D) for the VISX group, and -0.06+/-0.26 D (range: -0.75 to 0.75 D) for the Alcon group. Eighty-nine percent of eyes in the NIDEK group, 88% of eyes in the VISX group, and 92% of eyes in the Alcon group were within a half-diopter of intended correction. None of the NIDEK and VISX eyes and 3% of Alcon eyes lost 2 or more lines of best spectacle-corrected visual acuity. No statistically significant differences in any of the outcomes studied between conventional and custom ablation treatments were noted (P>.05). CONCLUSIONS: No statistically significant differences were observed in safety, efficacy, or predictability of eyes that underwent conventional ablation with the NIDEK EC-5000 scanning slit laser compared to custom ablation with the VISX CustomVue or Alcon CustomCornea laser systems.

Topographically guided laser in situ keratomileusis for myopia using a customized aspherical treatment zone.

PURPOSE: To assess the efficacy, predictability, safety, and quality-of-life effects of topography-guided laser in situ keratomileusis (LASIK) for the correction of myopia with astigmatism using the EC-5000 CXII excimer laser equipped with a customized aspheric treatment zone algorithm. SETTING: Ophthalmology clinics in the United States and Mexico. METHODS: In a multicenter United States Food and Drug Administration study of topography-guided LASIK, 4 centers enrolled 135 eyes with a spherical manifest refraction error ranging from -0.50 to -7.00 diopters (D) and astigmatism ranging from 0.50 to 4.00 D. All eyes were targeted for emmetropia. Refractive outcomes, higher-order aberrations (HOAs), and contrast sensitivity were analyzed preoperatively and postoperatively. Patient satisfaction was assessed using 2 questionnaires. RESULTS: Six months postoperatively, the mean manifest refraction spherical equivalent in all eyes was -0.09 D +/- 0.31 (SD); of the 131 eyes, 116 (88.55%) had an uncorrected visual acuity of 20/20 or better and 122 (93.13%) had an MRSE within +/-0.50 D. The best spectacle-corrected visual acuity (BSCVA) increased by 2 or more lines in 21 (16.03%) of 131 eyes; no eye lost 2 lines or more of BSCVA. The total ocular HOA increased by 0.04 microm. Patients reported significantly fewer night driving and glare/halo symptoms postoperatively than preoperatively. CONCLUSION: Use of a customized aspherical treatment zone in eyes with myopia and astigmatism was safe, effective, and predictable and reduced symptoms associated with night driving, glare, and halos.

Comparison of laser epithelial keratomileusis with and without mitomycin C for wavefront customized surface ablations.

PURPOSE: To investigate the efficacy of mitomycin C (MMC) in preventing haze formation in surface wavefront customized ablations with successful refractive treatment (laser epithelial keratomileusis [LASEK]) and to evaluate the safety of this technique on corneal stroma and endothelium. METHODS: This study was a prospective, double-masked, randomized clinical trial involving 52 eyes (30 placebo and 22 MMC) of 26 patients. The manifest refractive spherical equivalent (MRSE), best spectacle-corrected visual acuity, uncorrected visual acuity, corneal pachymetry, topography, aberrometry, endothelial specular microscopy, contrast sensitivity, corneal confocal microscopy, and complaints of pain via a subjective questionnaire were recorded preoperatively and 90 days postoperatively. RESULTS: The mean MRSE at 90 days postoperatively was -0.56 diopters (D) (-4.95 +/- 1.85 D, range: -8.00 to -1.62 D) for the MMC group and -0.49 D (-4.51 +/- 1.81 D, range: -7.75 to -2.25 D) for the placebo group. Higher order aberrations were similar between the placebo and MMC groups 90 days postoperatively (0.538 +/- 0.228 microm and 0.478 +/- 0.134 microm, respectively). Analysis of the endothelial cell count indicated a statistically significant decrease in endothelial cell density (P = .017) after LASEK, independent of MMC use. CONCLUSIONS: The predictability of the final target refraction, induction of high order aberrations, and improvement in contrast sensitivity proved that the use of MMC was equally safe when compared to procedures that did not use MMC. In addition, the procedure was efficient in the prevention of corneal haze.

Active cyclotorsion error correction during LASIK for myopia and myopic astigmatism with the NIDEK EC-5000 CX III laser.

PURPOSE: To investigate the predictability and accuracy of active cyclotorsion compensation during LASIK for myopia with astigmatism. METHODS: Fifty-two eyes of 26 patients were divided into two groups; one group (30 eyes) underwent primary LASIK with torsion error correction (TEC [TEC group]) and 22 eyes underwent LASIK without TEC (control group). The NIDEK EC-5000 CX III excimer laser was used for all treatments. All eyes were targeted for emmetropia. Manifest refraction spherical equivalent (MRSE), refractive outcomes, and dispersion and predictability of manifest refractive cylinder were compared between the TEC and control groups. A P value < .01 was considered statistically significant. All outcomes are reported at 3 months postoperatively. RESULTS: Statistically significantly lower cylinder dispersion and mean manifest refractive cylinder postoperatively were demonstrated in the TEC group (P < .01). Final refractive cylinder for the TEC group was -0.21 +/- 0.16 diopters (D) (range: -0.62 to 0.00 D) and -0.56 +/- 0.34 D (range: -1.25 to 0.00 D) for the control group. No statistically significant differences in mean MRSE or safety (defined as a loss of 2 or more lines of best spectacle-corrected visual acuity) was noted between groups. CONCLUSIONS: LASIK with active cyclotorsion error correction increases the accuracy of cylinder correction.

Topographically guided LASIK for myopia using the Nidek CXII customized aspheric treatment zone (CATz).

PURPOSE: To assess the efficacy, predictability, and safety of topography-guided laser in situ keratomileusis (LASIK) for the surgical correction of low to moderate myopia with astigmatism using the Nidek CXIII excimer laser equipped with the customized aspheric treatment zone (CATz) algorithm. METHODS: In a multicenter US Food and Drug Administration study of topography-guided LASIK, 4 centers enrolled 135 eyes with manifest refraction sphere that ranged from -0.50 to -7.00 D (mean, -3.57 +/- 1.45) with up to -4.00 D of astigmatism (mean, -1.02 +/- 0.64 D). The intended outcome was plano in all eyes. Refractive outcomes and higher-order aberrations were analyzed preoperatively and postoperatively. Patient satisfaction was assessed using both the validated Refractive Status and Vision Profile (RSVP) questionnaire and a questionnaire designed for this study. Six-month postoperative outcomes are reported here. RESULTS: By 6 months postoperatively, the manifest refraction spherical equivalent (MRSE) for all eyes was -0.09 +/- 0.31 D. Six months postoperatively, 116 of 131 eyes (88.55%) had an uncorrected visual acuity of 20/20 or better, and 122 of 131 eyes (93.13%) had a MRSE within +/-0.50 D. Distance best spectacle-corrected visual acuity (BSCVA) increased by 2 or more lines in 21 of 131 eyes (19.01%), and no eyes lost 2 lines or more of BSCVA. The total ocular higher-order aberrations root-mean-square increased by 0.04 microm postoperatively. Patients reported significantly fewer night driving and glare and halo symptoms postoperatively than preoperatively. CONCLUSIONS: Nidek CXIII CATz treatment of myopia with astigmatism is safe, efficacious, and predictable, and it reduces patient symptoms associated with night driving and glare and halo symptoms.

Wavefront analysis in Asian-Brazilians.

PURPOSE: To compare the distribution of ocular higher order wavefront aberrations (third to sixth order) in the Brazilian population of Asian and non-Asian refractive surgery patients. METHODS: Preoperative refractive and wavefront data were reviewed for 648 eyes in 324 patients who underwent custom ablation at the Excimer Laser Santa Cruz refractive surgery center in São Paulo, Brazil, from March 2002 to July 2005. Patients were divided into two groups: Asian patients and non-Asian patients, based on family history. Statistical analysis was performed to assess the differences between the groups with respect to manifest refractive spherical equivalent, astigmatism, pachymetry, OPD-root-square-mean (RMS) for a 6.0-mm pupil, total wavefront aberrations, third- to sixth-order higher order aberrations, and individual aberrations. RESULTS: The mean spherical equivalent refraction in the Asian group of -4.38 diopters (D) was significantly higher than the spherical equivalent refraction of -3.46 D in the non-Asian group (t= -4.32; P=.00001). Comparison of the differences between groups with respect to higher order aberrations, coma, trefoil, quadrafoil, spherical aberration, higher order astigmatism, and pachymetry was not statistically significant. CONCLUSIONS: Asian patients have a higher prevalence of myopia than non-Asian patients. No differences were noted in higher order aberrations between Asian and non-Asian patients.

Optimized prolate ablations with the NIDEK CXII excimer laser.

PURPOSE: To describe a novel excimer laser ablation algorithm, termed optimized prolate ablation (OPA), that uses both topography and ocular aberrometry and maintains or improves the natural corneal shape postoperatively. METHODS: A descriptive article outlining the theory behind this OPA algorithm. RESULTS: The theoretical changes to the ablation algorithm described in this article will produce a prolate cornea postoperatively. CONCLUSIONS: OPA treated eyes will have equal or better visual quality than preoperatively because age-related changes from lenticular spherical aberration are measured and treated.