Optical quality in eyes implanted with aspheric and spherical intraocular lenses assessed by NIDEK OPD-Scan: a randomized, bilateral, clinical trial.

PURPOSE: To determine whether implantation of an intraocular lens (IOL) with an aspheric surface (Akreos AO, Bausch & Lomb Inc) results in reduced ocular aberrations (spherical aberration) and improved Strehl ratio and modulation transfer function (MTF) after cataract surgery. METHODS: In an intraindividual, randomized, double-masked, prospective study of 50 eyes (25 patients) with bilateral cataract, an IOL with modified anterior and posterior surfaces (Akreos AO) was implanted in one eye and a biconvex IOL with spherical surfaces (Akreos Fit, Bausch & Lomb Inc) implanted in the fellow eye. Ocular aberrations, Strehl ratio, and MTF curve with 4.5-, 5.0-, and 6.0-mm pupils were measured with a NIDEK OPD-Scan dynamic retinoscopy aberrometer 3 months after surgery. Uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively) were also measured. RESULTS: No statistically significant difference was noted between eyes in postoperative UDVA and CDVA at 1 month. At 3 months, the Akreos AO IOL group obtained statistically significant lower values of higher order and spherical aberrations with 4.5-, 5.0-, and 6.0-mm pupil diameters than the Akreos Fit IOL group (P<.05). The value of Strehl ratio was statistically significantly higher in eyes with the Akreos AO IOL for 4.5- and 6.0-mm pupils (P<.05). The MTF curve was better in the Akreos AO IOL group in 4.5-, 5.0-, and 6.0-mm pupils (P<.05). CONCLUSIONS: The aspheric Akreos AO IOL induced significantly less spherical aberration than the Akreos Fit IOL for 4.5-, 5.0-, and 6.0-mm pupils. Modulation transfer function and Strehl ratio were also better in eyes implanted with the Akreos AO IOL than the Akreos Fit.

Intraocular straylight and contrast sensitivity after contralateral wavefront-guided LASIK and wavefront-guided PRK for myopia.

PURPOSE: To compare intraocular straylight measurements and contrast sensitivity after wavefront-guided LASIK (WFG LASIK) in one eye and wavefront-guided photorefractive keratectomy (WFG PRK) in the fellow eye for myopia and myopic astigmatism correction. METHODS: A prospective, randomized study of 22 eyes of 11 patients who underwent simultaneous WFG LASIK and WFG PRK (contralateral eye). Both groups were treated with the NIDEK Advanced Vision Excimer Laser System, and a microkeratome was used for flap creation in the WFG LASIK group. High and low contrast visual acuity, wavefront analysis, contrast sensitivity, and retinal straylight measurements were performed preoperatively and at 3, 6, and 12 months postoperatively. A third-generation straylight meter, C-Quant (Oculus Optikgeräte GmbH), was used for measuring intraocular straylight. RESULTS: Twelve months postoperatively, mean uncorrected distance visual acuity was -0.06 +/- 0.07 logMAR in the WFG LASIK group and -0.10 +/- 0.10 logMAR in the WFG PRK group. Mean preoperative intraocular straylight was 0.94 +/- 0.12 logs for the WFG LASIK group and 0.96 +/- 0.11 logs for the WFG PRK group. After 12 months, the mean straylight value was 1.01 +/- 0.1 log s for the WFG LASIK group and 0.97 +/- 0.12 log s for the WFG PRK group. No difference was found between techniques after 12 months (P = .306). No significant difference in photopic and mesopic contrast sensitivity between groups was noted. CONCLUSIONS: Intraocular straylight showed no statistically significant increase 1 year after WFG LASIK and WFG PRK. Higher order aberrations increased significantly after surgery for both groups. Nevertheless, WFG LASIK and WFG PRK yielded excellent visual acuity and contrast sensitivity performance without significant differences between techniques.

Topography-guided (NIDEK customized aspheric treatment zone) photorefractive keratectomy with mitomycin C after penetrating keratoplasty for keratoconus: case report.

PURPOSE: To report topography-guided photorefractive keratectomy (PRK) with mitomycin C (MMC) after penetrating keratoplasty for keratoconus. METHODS: A 34-year-old woman with irregular astigmatism after penetrating keratoplasty in the right eye underwent PRK. Topography-guided surface ablation using the customized aspheric treatment zone ablation (CATz) was programmed for a 5.00-mm optical zone and an 8.50-mm transition zone. Mitomycin C was applied to corneal stroma for 20 seconds immediately after excimer laser ablation. RESULTS: Two months after surgery, the patient was very satisfied with the refractive outcome. Best spectacle-corrected visual acuity was 20/20 with a manifest refraction of -0.50 diopters. No haze formation was detected at 6-month follow-up. A significant improvement in the central 3 mm of the axial topography was noted. CONCLUSIONS: Topography-guided ablation using MMC may be a reasonable alternative for the management of refractive error after penetrating keratoplasty.

Slit-scanning topography in vernal keratoconjunctivitis.

PURPOSE: To determine slit-scanning topographic (SST) pattern of eyes with vernal keratoconjunctivitis (VKC) and to detect the incidence of keratoconus in this population when compared with a healthy control group. DESIGN: Cross-sectional study. METHODS: A total of 104 patients, 50 eyes with VKC and 54 normal eyes, were included in this study. A comparison was performed between the two groups on the basis of SST data. Distribution curves were established for anterior and posterior elevation peaks, and for the pachymetric index. RESULTS: Anterior and posterior elevation peaks, elevation color patterns, central curvature, thinnest pachymetry, and pachymetric index differed significantly between VKC and control group (P < .05). Distribution curves have also shown abnormal patterns in VKC. Significant correlations were found between elevation peaks and pachymetric index (P < .001), and exponential curves were plotted. A higher frequency of keratoconus was found in the VKC group (P < .01). CONCLUSIONS: Patients with VKC have more abnormal corneal SST patterns than controls. SST abnormal findings may alert us for the risk of keratoconus in this population.

Precision of higher order aberration repeatability with NIDEK OPD-scan retinoscopic aberrometry.

PURPOSE: To evaluate repeatability of the total high order aberrations with a retinoscopic wavefront sensor. METHODS: This prospective case series analyzed 12 eyes from 6 patients who underwent wavefront measurement using retinoscopic aberrometry with the NIDEK Optical Path Difference Scan (OPD-Scan). Four consecutive wavefront measurements of each eye were taken by two trained examiners for 5.8+/-0.8-mm and 8.2+/-0.6-mm pupils (P=.002, Wilcoxon test). Total high order aberrations out to the eighth order were assessed including third order coma, third order trefoil, fourth order quadrafoil, fourth order secondary astigmatism, and fourth order spherical aberrations. Differences between measurements of all of the variables were analyzed. A P value <.05 was considered statistically significant. RESULTS: Repeatability analysis of the root-mean-square of total higher order aberrations, coma, trefoil, quadrafoil, secondary astigmatism, and spherical aberrations for both dilated and nondilated pupils did not show a statistically significant difference among all repeated measurements, except for trefoil and secondary astigmatism (analysis of variance and the Friedman test). The repeatability of total higher order aberrations was 0.15 microm for nondilated pupils and 0.18 microm for dilated pupils. Except for trefoil measurements, all high order aberrations showed reproducibility >0.15 microm when Zernike coefficients were analyzed individually. CONCLUSIONS: The NIDEK OPD-Scan aberrometer measures total higher order astigmatism and most individual aberrations with acceptable repeatability. However, measurement of trefoil with this instrument is less repeatable.

Dynamic contour tonometry and goldman applanation tonometry in eyes with keratoconus.

PURPOSE: The dynamic contour tonometer is a nonapplanation contact tonometer designed to be largely independent of the structural properties of the cornea. Theoretically, it may measure intraocular pressure most accurately in abnormally thinner corneas. This study compares intraocular pressure measurements by dynamic contour tonometry with Goldman applanation tonometry in eyes with normal corneas and eyes with advanced keratoconus. METHODS: A comparative case series. Subjects underwent intraocular pressure measurements by dynamic contour tonometry, Goldman applanation tonometry, ultrasonic pachymetry, and slit scanning topography. EXCLUSION CRITERIA: any ocular pathology other than keratoconus, previous corneal or refractive surgery, stromal scarring due to acute hydrops, or any other corneal opacities. RESULTS: Ten patients with keratoconus were included in Group A, and 12 normal patients composed Group B according to the pre-established criteria. The mean Goldman tonometry measurement in group A was 10.3 +/- 1.8 mm Hg and group B was 14.3 +/- 0.75 mm Hg. (P = 0.024). In group A, the mean measurement with the dynamic contour tonometer was 14.6 +/- 2.09 mm Hg, and in group B, it was 17.4 +/- 3.1 mm Hg (P = 0.026). The difference between both methods of measurement in group A was statistically significant (P < 0.0002). CONCLUSION: Intraocular pressure readings with dynamic contour tonometry in the keratoconus group were significantly higher than Goldman measurements and lower when compared to the control group. As there are no published manometric studies in eyes with keratoconus, these lower intra-ocular readings with the dynamic contour tonometry could be related to the discrepancy between the radius of corneal curvature and its tip, the significant thinning of the cornea, or other corneal biomechanical abnormalities related to advanced keratoconus.

Wavefront analysis and modulation transfer function of three multifocal intraocular lenses.

PURPOSE: To evaluate wavefront performance and modulation transfer function (MTF) in the human eye after the implantation of diffractive or refractive multifocal intraocular lenses (IOLs). MATERIALS AND METHODS: This was a prospective, interventional, comparative, nonrandomized clinical study. Uncorrected distance and near visual acuity, and wavefront analysis including MTF curves (iTrace aberrometer, Tracey Technologies, Houston, TX, USA) were measured in 60 patients after bilateral IOL implantation with 6 months of follow-up. Forty eyes received the diffractive ReSTOR (Alcon), 40 eyes received the refractive ReZoom (Advanced Medical Optics) and 40 eyes, the Tecnis ZM900 (Advanced Medical Optics). The comparison of MTF and aberration between the intraocular lenses was performed using analysis of variance (ANOVA), followed by the Dunn test when necessary. RESULTS: The mean uncorrected distance visual acuity was similar in all three groups of multifocal IOLs. The ReSTOR group provided better uncorrected near visual acuity than the ReZoom group (P<0.001), but similar to the Tecnis group. Spherical aberration was significantly higher in the ReZoom group (P=0.007). Similar MTF curves were found for the aspheric multifocal IOL Tecnis and the spheric multifocal IOL ReSTOR, and both performed better than the multifocal IOL ReZoom in a 5 mm pupil (P<0.001 at all spatial frequencies). CONCLUSIONS: Diffractive IOLs studied presented similar MTF curves for a 5 mm pupil diameter. Both diffractive IOLs showed similar spherical aberration, which was significantly better with the full-diffractive IOL Tecnis than with the refractive IOL ReZoom.

Wavefront analysis, contrast sensitivity, and depth of focus after cataract surgery with aspherical intraocular lens implantation.

PURPOSE: To determine whether implantation of an aspherical intraocular lens (IOL) results in reduced ocular aberrations and improved contrast sensitivity after cataract surgery without critical reduction of depth of focus. DESIGN: Double-blinded, randomized, prospective study. METHODS: In an intraindividual study of 25 patients with bilateral cataract, an aspherical IOL (Akreos Advanced Optic [AO]; Bausch & Lomb, Inc., Rochester, New York, USA) was implanted in one eye and a spherical IOL (Akreos Fit; Bausch & Lomb, Inc) in the fellow eye. Higher-order aberrations with a 5- and 6-mm pupil were measured with a dynamic retinoscopy aberrometer at 1 and 3 months after surgery. Uncorrected and best-corrected visual acuity and contrast sensitivity under mesopic and photopic conditions also were measured. Distance-corrected near and intermediate visual acuity were studied as a measurement of depth of focus. RESULTS: There was no statistically significant difference between eyes in uncorrected and best-corrected visual acuity at 1 and 3 months after surgery. There was a statistically significant between-group difference in contrast sensitivity under photopic conditions at 12 cycles per degree and under mesopic conditions at all spatial frequencies. The Akreos AO group obtained statistically significant lower values of higher-order aberrations and spherical aberration with 5- and 6-mm pupils compared with the Akreos Fit group (P < .05). There was no significant difference in distance-corrected near and intermediate visual acuity between both groups. CONCLUSIONS: Aspherical aberration-free Akreos AO IOL induced significantly less higher-order aberrations and spherical aberration than the Akreos Fit. Contrast sensitivity was better under mesopic conditions with the Akreos AO with similar results of depth of focus.

A contralateral eye study comparing apodized diffractive and full diffractive lenses: wavefront analysis and distance and near uncorrected visual acuity.

PURPOSE: To evaluate intraindividual visual acuity, wavefront errors and modulation transfer functions in patients implanted with two diffractive multifocal intraocular lenses. METHODS: This prospective study examined 40 eyes of 20 cataract patients who underwent phacoemulsification and implantation of a spherical multifocal ReSTOR intraocular lens in one eye and an aspheric Tecnis ZM900 multifocal intraocular lens in the other eye. The main outcome measures, over a 3-month follow-up period, were the uncorrected photopic distance and near visual acuity and the defocus curve. The visual acuity was converted to logMAR for statistical analysis and is presented in decimal scale. The wavefront error and modulation transfer function were also evaluated in both groups. RESULTS: At the 3-month postoperative visit, the mean photopic distance uncorrected visual acuity (UCVA) was 0.74 +/- 0.20 in the ReSTOR group and 0.76 +/- 0.22 in the Tecnis group (p=0.286). The mean near UCVA was 0.96 +/- 0.10 in the ReSTOR group and 0.93 +/- 0.14 in the Tecnis group (p=0.963). The binocular defocus curve showed measurements between the peaks better than 0.2 logMAR. The total aberration, higher-order aberration and coma aberration were not significantly different between the groups. The spherical aberration was significantly lower in the Tecnis group than in the ReSTOR group. (p=0.004). Both groups performed similarly for the modulation transfer function. CONCLUSION: The ReSTOR SN60D3 and Tecnis ZM 900 intraocular lenses provided similar photopic visual acuity at distance and near. The diffractive intraocular lenses studied provided a low value of coma and spherical aberrations, with the Tecnis intraocular lens having a statistically lower spherical aberration compared to the ReSTOR intraocular lens. In the 5 mm pupil diameter analyses, both intraocular lens groups showed similar modulation transfer functions.

[Evaluation of optical performance of soft contact lenses in myopic correction]. / Avaliação da qualidade óptica de lentes de contato gelatinosas na correção de miopia.

PURPOSE: To evaluate the optical performance of eyes fitted with two different soft contact lenses: Acuvue 2 (Vistacon J&J Vision Care Inc., USA) and World Vision Disposable Asférica Wave Front (World Vision Ophthalmic, Brazil). METHODS: An interventional prospective clinical trial studied a sample of 40 myopic patients (-0.75D to -4.50D, with or without astigmatism up to -0.75D). Each patient had one eye randomized to visual performance evaluation including high and low contrast visual acuities, wavefront analysis and contrast sensitivity. RESULTS: The Nidek OPD Scan detected a residual refraction (hypercorrection) for both contact lenses. High contrast visual acuity was significantly higher for World Vision soft contact lenses. Low contrast visual acuity was similar for both soft contact lenses. Contrast sensitivity improved significantly at 1.5; 3; 6 e 18 spatial frequencies for both soft contact lenses, but no difference was found between them. Regarding wavefront analysis, no difference was found between both soft contact lenses. There were not significantly differences in the Strehl indices and MTF for both soft contact lenses. CONCLUSION: World Vision Disposable Asférica Wave Front soft contact lenses had a better performance regarding high contrast visual acuity. However, low contrast visual acuity, wavefront analysis and contrast sensitivity were similar for both soft contact lenses.