Order Wavefront Research Articles

Visual quality evaluation on changes of MTF and wavefront aberration after laser in situ keratomileusis

To investigate the changes of the Modulation Transfer Function (MTF) and its effect on visual and optical quality with or without low and higher order wavefront aberration after conventional and wavefront guild laser in situ keratomileusis. It was a comparative case series. An aberrometer with Hartmann-shark sensor was used to measure the monochromatic aberration of eyes. One hundred and two cases entered the study; 38 cases were randomized to LASIK and 64 were randomized to WFG-LASIK. MTFs of optical system were calculated at various pupil size (3, 4, 5 and 6 mm) respectively and compared pre and 3 month postoperatively between conventional and wavefront guide ablation with or without higher order aberration. There was a significant increase in MTF positively compared with preoperative values at all spatial frequency (5-60 cycles per degree, c/d ), P < 0.05. MTF values got more improvement without spherical aberration than without coma aberration after LASIK surgery and there was significant different at a spatial frequency of 5 c/d. Higher MTFs were showed in the WFG-LASIK group although there were no significant difference between conventional LASIK group and WFG-LASIK group. However, there were apparently changed without high order aberration as compared to that with high order aberration at all spatial frequency (5-60 c/d. ) in WFG-LASIK group and higher MTFs were showed in the WFG-LASIK group compared with conventional LASIK group and there were significant different (P < 0.05) by calculation and evaluation. Spherical aberration have more negative role on visual quality than coma aberration after LASIK surgery. With the optical benefits expected from correcting higher aberration, wavefront guide ablation have shown a great benefit for low and high order aberration but it still leave a small amount of high order aberration and need further investigation. MTF is a sensitive and extensive in demonstrating the optical quality in refractive surgery.

Dynamic wavefront aberrations and visual acuity in normal and dry eyes

Purpose: The aim was to study the dynamic properties of wavefront aberrations and visual acuity in normal and dry eyes.Methods: Thirty dry‐eye patients and 27 normal subjects participated in this study. Multi‐file mode of a Hartmann‐Shack wavefront sensor was used to measure dynamic wavefront aberrations for a period of 45 seconds. Dynamic measurements of visual acuity (VA) were made for 150 seconds using a multi‐functional VA tester. Standard deviation of the measurements (RMS or VA) over the testing period was used to estimate instability of the dynamic wavefront aberration and VA.Results: For most subjects, both wavefront aberration and VA changed over time and the instability varied substantially among individuals. Blink‐dependent fluctuation in wavefront aberration or VA was observed for some dry‐eye subjects. On average, the dry‐eye group had greater instability than the normal group in either the higher order wavefront aberrations (t = 2.09, p = 0.03, for OD; t = 3.76, p = 0.001, for OS) or the VA (t = 2.09, p = 0.02, for OD; t = 204, p = 0.03, for OS). Instability of VA in the dry‐eye group was significantly correlated with blink rate (r = 0.28, p = 0.02).Conclusion: Dynamic changes in wavefront aberrations and VA are highly individual dependent, while the dry eye tends to be less stable than the normal eye. The results suggest that tear‐film fluctuation might play a role in determining dynamic wavefront aberration and VA, however, contributions from other factors should not be overlooked. For dry eye, dynamic change in VA depends on blink rate.

CORONAGRAPHIC LOW-ORDER WAVE-FRONT SENSOR: PRINCIPLE AND APPLICATION TO A PHASE-INDUCED AMPLITUDE CORONAGRAPH

High contrast coronagraphic imaging of the immediate surrounding of stars requires exquisite control of low-order wavefront aberrations, such as tip-tilt (pointing) and focus. We propose an accurate, efficient and easy to implement technique to measure such aberrations in coronagraphs which use a focal plane mask to block starlight. The Coronagraphic Low Order Wavefront Sensor (CLOWFS) produces a defocused image of a reflective focal plane ring to measure low order aberrations. Even for small levels of wavefront aberration, the proposed scheme produces large intensity signals which can be easily measured, and therefore does not require highly accurate calibration of either the detector or optical elements. The CLOWFS achieves nearly optimal sensitivity and is immune from non-common path errors. This technique is especially well suited for high performance low inner working angle (IWA) coronagraphs. On phase-induced amplitude apodization (PIAA) type coronagraphs, it can unambiguously recover aberrations which originate from either side of the beam shaping introduced by the PIAA optics. We show that the proposed CLOWFS can measure sub-milliarcsecond telescope pointing errors several orders of magnitude faster than would be possible in the coronagraphic science focal plane alone, and can also accurately calibrate residual coronagraphic leaks due to residual low order aberrations. We have demonstrated 1e-3 lambda/D pointing stability in a laboratory demonstration of the CLOWFS on a PIAA type coronagraph.

Variability of Higher Order Wavefront Aberrations After Blinks

To investigate the rapid alterations in value and fluctuation of ocular wavefront aberrations during the interblink interval. Forty-two volunteers were examined with a WASCA Wavefront Analyzer (Carl Zeiss Meditec AG) using modified software. For each subject, 150 images (about 6 frames/second) were registered during an interblink period. The outcome measures were spherical and cylindrical refraction and root-mean-square (RMS) values for spherical, coma, and total higher order aberrations. Fifth order polynomials were fitted to the data and the fluctuation trends of the parameters were determined. We calculated the prevalence of the trends with an early local minimum (type 1). The tear production status (Schirmer test) and tear film break-up time (BUT) were also measured. Fluctuation trends with an early minimum (type 1) were significantly more frequent than trends with an early local maximum (type 2) for total higher order aberrations RMS (P=.036). The incidence of type 1 fluctuation trends was significantly greater for coma and total higher order aberrations RMS (P=.041 and P=.003, respectively) in subjects with normal results in the BUT or Schirmer test than in those with abnormal results. In the normal subjects, the first minimum of type 1 RMS fluctuation trends occurred, on average, between 3.8 and 5.1 seconds after blink. We suggest that wavefront aberrations can be measured most accurately at the time after blink when they exhibit a decreased degree of dispersion. We recommend that a snapshot of wavefront measurements be made 3 to 5 seconds after blink.

Wavefront analysis of acrylic spherical and aspherical intraocular lenses

To compare higher order wavefront aberrations in eyes implanted with acrylic aspherical intraocular lenses (IOLs) with a modified prolate anterior surface with conventional acrylic spherical IOLs by using the optical path difference method. In a nonrandomized parallel cohort investigation, 36 eyes of 31 patients implanted with aspherical IOLs (Tecnis ZA9003) and 37 eyes of 23 age-matched patients implanted with spherical IOLs (SENSOR AR40e) were evaluated with a wavefront analyzer (OPD-Scan II) preoperatively and 1 month after surgery. The higher order aberrations for a 4.0-mm pupil diameter were expanded into Zernike's polynomial expression. Coma aberration, spherical aberration, and total higher order aberrations were evaluated as root mean square values. Postoperatively, coma and total higher order aberrations of spherical and aspherical IOLs significantly improved in both eyes. Spherical aberration improved in eyes with aspherical IOLs only (P < 0.01). After implantation of acrylic aspherical IOLs, postoperative higher order aberrations were not necessarily lower than after implantation of acrylic spherical IOLs, but compared with levels following implantation of acrylic spherical IOLs, a significant reduction in spherical aberration was achieved.

Effect of Flap Thickness on Higher Order Wavefront Aberrations Induced by LASIK: A Bilateral Study

To investigate the effect of flap thickness on wavefront aberrations induced by LASIK. LASIK was performed on 56 eyes of 28 patients with refraction errors that were well matched between the right and left eyes. For each patient, a planned 160-microm flap was created for one randomly selected eye using the Moria M2 microkeratome (130-microm head; thick flap group), and a 110-microm flap was created for the contralateral eye with the same microkeratome (90-microm head; thin flap group). Flap thickness was measured using ultrasonic pachymetry. Wavefront aberrations were measured in the anterior cornea using the Orbscan II (Bausch & Lomb) and in the whole eye using the Wavefront Supported Custom Ablation (WASCA) aberrometer (Carl Zeiss Meditec) preoperatively and at 1 month and 1 year postoperatively. Mean flap thickness was 155 +/- 13 microm in the thick flap group and 112 +/- 11 microm in the thin flap group. Mean root-mean-square of higher order wavefront aberrations were changed for the different test times in the cornea (F = 29.9, P < .0001) and the whole eye (F = 48.0, P < .0001). There was no significant difference between the two flap groups for the cornea (F = 0.76) or for the whole eye (F = 0.07). Similar results were observed for higher order Zernike aberrations such as spherical aberration and comas. The results suggest higher order wavefront aberrations induced by LASIK are independent of flap thickness. Complications in visual outcome for patients with different flap thickness should be attributed to factors other than aberrations.

High order wavefront correction for a 1 joule class Nd:YLF rod amplifier by phase conjugate plate

Wavefront correction until Zernike polynomial of degree three by a phase conjugate plate has been demonstrated in a high-energy Nd:YLF amplifier system. 108, amplification of 380 mJ has been achieved with a near-diffraction-limited beam quality.

Influence of Age on Ocular Wavefront Aberration Changes With Accommodation

To perform a quantitative analysis of high order wavefront aberrations of the entire optical system of the eye that accompanies accommodation demands in the healthy and emmetropic eye. Fifty-six healthy emmetropic eyes of 30 patients were separated into three groups according to age: group 1, 20 to 29 years; group 2, 30 to 39 years; and group 3, 40 to 49 years. Using iTrace ray-tracing technology, pupil diameter, objective refraction, and wavefront aberrations at accommodation demands of 0 to 4.00 diopters (D) in five 1.00-D increments were determined. In analyzing higher order aberrations in the central 4-mm diameter zone of the pupil, Zernike polynomials were used to study the changes associated with accommodation in the magnitude of total higher order aberrations, third order aberrations (coma-like aberrations), fourth order aberrations (spherical-like aberrations), and the spherical aberration component (C4(0)) of the fourth order aberrations. Pupil diameter decreased significantly (P < .05) with accommodation demand in each group. Total higher order aberrations in group 1 increased significantly (P < .05). No significant change was seen in third order aberrations in any group, but fourth order aberrations increased significantly (P < .05) in group 1. Spherical aberration (C4(0)) showed phase shifts from positive to negative in all groups, but the shift in group 3 was minimal, remaining positive even for a 4.00-D accommodation demand. Among higher order aberrations accompanying accommodation demands, spherical aberration (C4(0)) in particular showed characteristic changes; however, these changes showed age-related disparities. The changes were probably due to the effects of reduction in accommodation resulting from age-related changes in the crystalline lens.

Wavefront-Versus Topography-guided Customized Ablations With the NIDEK EC-5000 CX II in Surface Ablation Treatment: Refractive and Aberrometric Outcomes

To compare the long-term refractive outcomes and changes in higher order wavefront aberrations in patients undergoing photorefractive keratectomy (PRK) with topography-guided (CATz) or wavefront-guided (OPDCAT) ablation algorithm using the NIDEK Advanced Vision Excimer Laser System (NAVEX). A retrospective 12-month follow-up study was conducted of 226 eyes undergoing PRK. The NIDEK EC-5000 CX II excimer laser and Final Fit 1.11 treatment planning software were used. Sixty-eight eyes underwent OPDCAT ablation and 158 eyes underwent CATz ablation. Mean preoperative manifest refractive spherical equivalent (MRSE) was -5.73 +/- 2.03 diopters (D) (range: -11.25 to -2.50 D) in the OPDCAT group and -3.77 +/- 3.78 D (range: -12.50 to -5.75 D) in the CATz group. At 12 months postoperatively, mean MRSE was 0.05 D for the OPDCAT group and plano for the CATz group. Stability was similar in both groups as were visual outcomes. No eyes lost 2 or more lines of BSCVA at 6 months postoperatively or later. Mean ocular wavefront higher order aberrations at 3 months postoperatively were 0.44 +/- 0.17 microm for the OPDCAT group and 0.55 +/- 0.27 microm for the CATz group. Refractive outcomes were equivalent between eyes that underwent PRK with wavefront-guided ablation and those that underwent topography-guided ablation.

Higher Order Wavefront Aberrations and Topography in Early and Suspected Keratoconus

To determine whether higher order wavefront aberrations or a combination of topography and wavefront variables distinguishes between early and suspected keratoconus. This prospective comparative study evaluated 70 eyes using videokeratography (Tomey TMS-1) and aberrometry (Alcon LADARWave). Videokeratography and clinical evaluation were used to divide the eyes into three groups: 50 normal eyes, 10 eyes with early keratoconus, and 10 eyes with suspected keratoconus. Data were analyzed to determine whether higher order aberrations could separate eyes with early and suspected keratoconus from normal eyes. The product of the Inferior-Superior (I-S) topographic value in combination with the wavefront vertical coma also was evaluated to determine whether this could distinguish normal eyes from eyes with early and suspected keratoconus. Differences in vertical coma, root-mean-square coma, and secondary astigmatism for the three groups were statistically significant. Vertical coma was -0.03 +/- 0.28 for normal eyes, -0.525 +/- 0.253 for eyes with suspected keratoconus, and -1.949 +/- 1.416 for eyes with early keratoconus. Root-mean-square coma was 0.229 +/- 0.149 for normal eyes, 0.639 +/- 0.250 for eyes with suspected keratoconus, and 2.034 +/- 1.532 for eyes with early keratoconus. The product of vertical coma and the topographic I-S value separated the three groups better than aberrometry alone (P < .0001). Although both vertical coma and the I-S topographic value were useful for distinguishing among the three study groups, a combination of wavefront aberrometry and videokeratography appears to be the most sensitive way for distinguishing among normal eyes, eyes with suspected keratoconus, and eyes with early keratoconus.

Uncorrected Wavefront Error and Visual Performance During RGP Wear in Keratoconus

To examine the relationship between uncorrected residual wavefront error and visual performance (VP) in rigid gas permeable (RGP) contact lens-wearing keratoconic eyes. Seven eyes from six subjects (six moderate, one severe) were studied (mean +/- SD age: 42.71 +/- 11.38 years). Significant corneal scarring was an exclusion criterion. Measurements were taken with RGP lenses in place. After pupil dilation, the VP measures of high contrast logMAR visual acuity (VA) and Pelli-Robson contrast sensitivity (PRCS) were measured through a 5-mm artificial pupil. Wavefront error was measured using a Shack-Hartmann wavefront sensor and calculated over 5 mm. For both VP and wavefront error, comparisons were made to previously collected normal values by calculating the interval encompassing 95% of normals, then reporting how many of the seven keratoconic eyes fell outside the normal interval. Additionally, second to sixth order aberrations were processed into four previously reported image quality metrics: root mean square of the wavefront (RMSw), root mean square of the slope (RMSs), average blur strength (Bave) and diameter containing 50% light energy (D50) and regressed against VP measures. Five of seven keratoconic eyes fell outside the normal interval (-0.23 to 0.09) for VA and two of seven fell outside the normal interval (1.59 to 2.03) for PRCS. Five of seven keratoconic eyes fell outside the normal interval (0.07 to 0.35 microm) for total higher order RMS. Linear regressions demonstrated relationships between both VA and PRCS and the image quality metrics RMSw, D50, RMSs, and Bave with R values for VA = 0.30, 0.30, 0.47, 0.62, and PRCS = 0.21, 0.15, 0.45, 0.75 respectively. VP in RGP-wearing keratoconic eyes is reduced and higher order wavefront aberrations are elevated compared to normals. Metrics of retinal image quality demonstrate a relationship between keratoconic VP and residual wavefront aberrations. This relationship suggests developing corrections that more completely correct aberrations may improve visual performance in keratoconus.

Corneal Wavefront-guided Ablation With the Schwind ESIRIS Laser for Myopia

To evaluate the outcome of corneal wavefront-guided LASIK for the treatment of myopia and myopic astigmatism. This study included 56 myopic virgin eyes of 28 patients with a mean spherical equivalent refraction of -4.40 +/- 1.83 diopters (D) (range: -1.25 to -9.75 D) and astigmatism < 2.50 D. The corneal wavefront aberrations were analyzed using a corneal topography system. The preoperative corneal wavefront aberration data obtained from the above analyses combined with manifest refraction were used to generate a customized ablation profile. The safety, efficacy, and predictability of the correction, contrast sensitivity, and corneal higher order wavefront aberrations were evaluated. At 1-year follow-up, the mean residual spherical equivalent refractive error was -0.15 +/- 0.3 D (range: 0 to -1.25 D) and mean cylinder was -0.54 +/- 0.34 D (range: 0 to -1.50 D). Ninety-five percent of eyes were in the residual refractive error range of +/- 0.50 D and uncorrected visual acuity improved by 1.00 D or better in 94% of eyes. The safety index and efficacy index were 1.13 and 0.92, respectively. After treatment, corneal higher order wavefront aberrations with a 6-mm pupil diameter increased significantly (paired sample t test, P < .01), and contrast sensitivity with glare had small reductions at high spatial frequencies. Changes in spherical-like aberration (R = 0.708, P < .001) and higher order wavefront aberration (R = 0.449, P = .001), except for coma-like aberration (P = .238), were positively correlated with the amount of achieved correction. Evaluation of clinical results showed that corneal wavefront-guided LASIK for the correction of myopia and myopic astigmatism was safe and effective. There was an increase in all higher order aberrations postoperatively.

Age-Related changes in ocular aberrations with accommodation

This study investigates the changes in aberrations with monocular accommodation as a function of age. Second-order and higher order wavefront aberrations and pupil size were measured as a function of accommodation demand over the range of 0-4 D in the right eyes of 47 normal subjects with ages between 17 and 56 years. Higher order ocular Zernike aberrations were analyzed for the natural pupil size in terms of their equivalent defocus and were also determined for fixed pupil diameters of 4.5 mm in the unaccommodated eyes and 2.5 mm in the accommodating eyes. With relaxed accommodation (0 D accommodation stimulus), the major change with age was in the value of C4(0), which increased in positive value over the age range studied, although the total higher order RMS wavefront aberration did not increase. When the data were analyzed for natural pupils, spherical aberration was again found to change systematically in the positive direction with age. The equivalent defocus of total higher order RMS error for natural pupils showed no significant correlation with age (p > .05). With active accommodation, spherical aberration was found to decrease and become negative as the accommodative response increased in the younger subjects (<40 years). Near-zero spherical aberration was found at accommodation levels of about 0.50 D in the youngest subjects (<20 years) and at around 2-3 D in subjects between 20 and 39 years. In the older subjects (>40 years), the spherical aberration showed only small changes, some of which were positive, within the limited amplitude of accommodation available. Other higher order aberrations and the RMS of higher order aberrations did not appear to change systematically with accommodation, except in the oldest subjects. The change with age in the relationship between aberration and accommodation is interpreted in terms of the changing gradients of refractive index and surface curvatures of the crystalline lens.

503 Comparaison des aberrations optiques de haut degré entre implants phaques

Aim To evaluate higher order aberrations and contrast sensitivity after implantation of the Artisan/Verisyse® and the Icare phakic® intraocular lens (IOL). Aim and Methods In a prospective non randomized case series, Artisan/Verisyse® phakic IOL was implanted in 9 eyes and Icare phakic® IOL was implanted in 9 other eyes. Ocular wavefront aberrations were mesured 1 month postoperatively in all eyes using an IRX3 aberrometer. Zernike expansions were computed up to the 6th order and normalized to a 4 mm pupil diameter. The wavefront performance of the two IOLs were compared using non parametric statistics. Results The analysis revealed a difference in the distribution of spherical refraction between the two groups: this distribution was roughly centered on zero (emmetropia) with the Artisan/Verisyse® lens while it was shifted towards hyperopia, by less than 1 diopter, with the Icare® lens. No statistical difference in higher order RMS was found between the two IOLs. The average higher order RMS, as well as vertical coma, were slightly higher with the Verisyse® lens. Discussion Both IOLs present with very low high order aberrations. The slight difference observed in the vertical coma between the two may be due to the specific iris-claw design of the Artisan/Verisyse®. Conclusion Both IOLs has similar higher order wavefront performance. Spherical refraction was slightly hyperopic in average with the Icare lens: this may likely be improved using refined power calculations.

Laser Epithelial Keratomileusis for the Correction of Hyperopia Using a 7.0-mm Optical Zone With the Schwind ESIRIS Laser

To investigate the efficacy of laser epithelial keratomileusis (LASEK) for the correction of hyperopia using a 7.0-mm optical zone and a 9.0-mm total ablation zone diameter with the Schwind ESIRIS flying-spot laser. Forty-seven patients (70 eyes) were treated with a mean preoperative spherical equivalent refraction of +2.32 diopters (D) (range: 0 to +5.00 D). All eyes underwent LASEK using 15% alcohol with a 20-second application. An intact epithelial flap was obtained in 66 (94%) eyes. In 70 eyes at 12 months, the mean spherical equivalent refraction was +0.09 D (range: -0.75 to +1.00 D) with all (100%) eyes within +/- 1.00 D of the intended correction and 60 (86%) eyes within +/- 0.50 D. In 40 eyes with 24-month follow-up, the refractive correction remained stable after 6 months. Hyperopic cylindrical corrections were attempted in 49 eyes (range: +0.25 to +5.00 D) with vector analysis demonstrating a mean 102% correction at 12 to 24 months. In 60 non-amblyopic eyes, uncorrected visual acuity was > or = 20/20 in 47 (78%) eyes. Thirty-three (47%) eyes gained 1 to 2 lines of Snellen decimal equivalent best spectacle-corrected visual acuity, 30 (43%) eyes showed no change, and 7 (10%) eyes lost 1 line. Eight (11%) eyes at 12 to 24 months had grade +/- 1 of paracentral corneal haze and 57 (81%) had no haze. At 12 months (n = 70), the safety index was 1.06 with an efficacy index of 0.95. Analysis of higher order wavefront aberrations showed no significant changes in root-mean-square values post-operatively, except for a significant reduction of fourth order spherical aberration (P < .05). Laser epithelial keratomileusis for hyperopia up to +5.00 D using a 7.0-mm optical zone with the Schwind ESIRIS laser provides excellent refractive and visual outcomes with minimal complications. In eyes followed for 24 months, the refractive correction remained stable after 6 months.

Optical Factors in Increased Best Spectacle-corrected Visual Acuity After LASIK

To study the factors that correlate with improved best spectacle-corrected visual acuity (BSCVA) after LASIK. This was a nonrandomized, prospective clinical trial of 850 eyes from 480 patients undergoing LASIK for myopia, hyperopia, and mixed astigmatism. The mean preoperative spherical equivalent refraction was -3.75+/-4.82 diopters (D) (range: -13.88 to 6.00 D). From this population, 72 eyes (including 22 amblyopic eyes) from 43 patients were found to have improved BSCVA 6 months after LASIK. All patients underwent LASIK with the NAVEX platform. These eyes were analyzed to evaluate factors that correlated with improved BSCVA. Pre- and postoperative BSCVA, refraction, pupil diameter, corneal topography, asphericity (Q value), total aberrations, and higher order wavefront aberrations were analyzed. All wavefront aberrations were measured using the NIDEK Optical Path Difference Scan aberrometer (OPD-Scan) preoperatively and at 6 months postoperatively. Postoperatively, the mean sphere was -0.44 1.30 D (range: -4.50 to +2.50 D). The mean increase in BSCVA was 0.15+/-0.09 logMAR. A statistically significant negative correlation was observed between the increase in BSCVA and the preoperative BSCVA (P<.01). Mixed astigmatic and highly myopic eyes are more likely to gain BSCVA after LASIK than moderately myopic (P<.05) and hyperopic eyes (P<.001). In patients with myopia, the amount of BSCVA improvement correlated with the magnitude of the correction (P<.05). The induction of spherical aberration negatively correlated with the increase in BSCVA (P<.05). There were no significant differences between normal eyes and amblyopic eyes with respect to postoperative improvement in BSCVA (P>.05). Decreased preoperative BSCVA, lower total spherical aberration induction, and preoperative mixed astigmatism and high myopia correlate with an increase in BSCVA after LASIK.

Wavefront Analysis in Asian-Brazilians

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. 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. 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. 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.

Optical Quality Analysis After Surface Excimer Laser Ablation: The Relationship Between Wavefront Aberration and Subepithelial Haze

To investigate the relationship between mild and moderate corneal haze and the distribution of higher order wavefront aberrations after photorefractive keratectomy (PRK). Thirty-six eyes from 18 patients who underwent PRK were divided into two groups: 10 eyes with corneal haze and 26 eyes without corneal haze (control). All eyes were evaluated up to 6 months after PRK. Wavefront aberrations were measured using a psychophysical wavefront sensor and the NIDEK OPD-Scan. Topography, point spread function, and modulation transfer function maps were obtained from the OPD-Scan. The mean total higher order aberration was slightly higher in the corneal haze group than in the control group. This difference was not statistically significant. The mean third order coma aberrations were higher and mean fourth order spherical aberrations were lower in the haze group compared with the control group, although neither difference attained statistical significance. The t test values were 1.05, -0.38, -1.10, -0.08, and -0.23, when comparing the mean third, fourth, fifth, sixth, and seventh order aberrations, respectively. None of these differences attained statistical significance. In terms of Zernike coefficients, Z-1 and Z1 showed greater mean root-mean-square (RMS) in the haze group (0.33 and 0.35 microm, respectively) than those for the control group (0.26 and 0.23 microm, respectively) (t=0.71 and P=.49; t=0.84 and P=.43, respectively). However, ZO had lower RMS in the haze group (0.18 microm) than in the control group (0.28 microm). This difference also was not statistically significant. In this study comparing the optical aberrations of eyes with and without corneal haze after PRK, corneal haze did not affect the magnitude and distribution of higher order aberrations in a predictable manner.

Wavefront Analysis and Contrast Sensitivity of Aspheric and Spherical Intraocular Lenses: A Randomized Prospective Study

To compare visual performance, total and high order wavefront aberrations (coma, spherical aberration, and other terms), and contrast sensitivity in 120 eyes implanted with one monofocal aspheric intraocular lens (IOL) and two spherical IOLs. Randomized prospective study. Sixty patients were randomized to receive three IOL types: Alcon AcrySofIQ (40 eyes), AcrySofNatural (40 eyes), and advanced medical optic (AMO)Sensar (40 eyes). Complete ophthalmologic examination including uncorrected visual acuity (UCVA), best-spectacle corrected visual acuity (BSCVA), corneal topography, and wavefront analysis were performed preoperatively, 30 days, and 90 days postoperatively. Pelli-Robson chart test and functional acuity contrast testing (FACT-Optec6500) were performed approximately 50 days after surgery. Statistical analyses were performed using analysis chi(2), analysis of variance (ANOVA), and multiple comparisons Tukey test. After 90 days, all eyes had postoperative BSCVA > or =20/32. The AcrySofIQ IOL showed statistically significant less induction of spherical aberration (P < .001) when compared with the AMOSensar and the AcrySofNatural IOLs. The AMOSensar presented significantly less spherical aberration then the AcrySofNatural (P < .05). The AcrySofIQ also had lower values of total and high-order aberration (HOA) (P < .05) when compared with the AMOSensar and the AcrySofNatural. The mean values of trefoil 9, coma, and HOA root mean square (RMS) decreased between one and three months (P < .001, P < .001, P = .023, P < .001, respectively) in all groups. Mean Pelli-Robson contrast sensitivity values in photopic condition were similar between the groups. The AcrySofIQ showed better results in 3cpd spatial frequency in mesopic condition using FACT-Optec 6500 (P = .008), although there were no statistical differences in photopic and mesopic with glare conditions.

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

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. 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. Three months after LASIK, the predictability (10.5 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. 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.