Higher-order Wavefront Research Articles

Topical rosiglitazone is an effective anti-scarring agent in the cornea.

Corneal scarring remains a major cause of blindness world-wide, with limited treatment options, all of which have side-effects. Here, we tested the hypothesis that topical application of Rosiglitazone, a Thiazolidinedione and ligand of peroxisome proliferator activated receptor gamma (PPARγ), can effectively block scar formation in a cat model of corneal damage. Adult cats underwent bilateral epithelial debridement followed by excimer laser ablation of the central corneal stroma to a depth of ∼160 µm as a means of experimentally inducing a reproducible wound. Eyes were then left untreated, or received 50 µl of either 10 µM Rosiglitazone in DMSO/Celluvisc, DMSO/Celluvisc vehicle or Celluvisc vehicle twice daily for 2 weeks. Cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and post-mortem immunohistochemistry for alpha smooth muscle actin (αSMA). Impacts of the wound and treatments on optical quality were assessed using wavefront sensing and optical coherence tomography at 2, 4, 8 and 12 weeks post-operatively. In parallel, cat corneal fibroblasts were cultured to assess the effects of Rosiglitazone on TGFβ-induced αSMA expression. Topical application of Rosiglitazone to cat eyes after injury decreased αSMA expression and haze, as well as the induction of lower-order and residual, higher-order wavefront aberrations compared to vehicle-treated eyes. Rosiglitazone also inhibited TGFβ-induced αSMA expression in cultured corneal fibroblasts. In conclusion, Rosiglitazone effectively controlled corneal fibrosis in vivo and in vitro, while restoring corneal thickness and optics. Its topical application may represent an effective, new avenue for the prevention of corneal scarring with distinct advantages for pathologically thin corneas.

Ocular higher-order aberration features 10 years after photorefractive keratectomy

The aim of the present study is to re-evaluate the original cohort of patients who participated in the first photorefractive keratectomy (PRK) trial in the 1990s, especially their optical performance. Forty-four eyes (24 patients) of the original cohort who underwent PRK using the NIDK EC-5000 excimer laser platform returned 10years (range 9-14years) postoperatively to have higher-order aberrations (HOAs) recorded. Wavefront aberrations were measured using Wavescan (VISX, Santa Clara, CA, USA) and calculated for 3- and 6-mm pupil size. The total RMS (the square root of the sum of squared Zernike coefficients) of higher-order wavefront error (3rd-6th radial order) and the Zernike coefficients, as well as the third-order (S 3) and fourth-order (S 4) aberrations, spherical aberrations and coma aberration values were analyzed. An independent sample t test was used for comparisons and a P value<0.05 was considered statistically significant. The mean RMS of higher-order wavefront values showed an increase but no significant difference in postoperative eyes compared to the control-matched normal level with the 6-mm pupil (HOA RMS: control group 0.31±0.12μm; 10-year post-PRK group 0.56±0.15μm; P=0.141). The main contribution was the increase of spherical aberrations (Z 12) and spherical-like aberrations (S 4), which increased by fourfold and 2.5-fold, respectively, in the 10-year post-PRK group (control group Z 12 0.08±0.11μm, S 4 0.14±0.05μm; 10-year post-PRK group Z 12 0.35±0.15μm, S 4 0.37±0.14μm; P=0.010*). Most increases of ocular HOAs induced by corneal refractive surgery are becoming extremely minor at 10years postoperatively, closer to the corresponding preoperative amount. The largest increase was spherical and spherical-like aberrations, especially with a larger pupil size.

Influence of decorative lenses on higher-order wavefront aberrations

To investigate the influence of decorative lenses on ocular wavefront aberrations. A wavefront analyzer was used to measure higher-order aberrations (HOAs) in 20 right eyes of 20 participants while they were wearing Vistacon contact lenses of different designs, namely, clear 1-day Acuvue, ring-design circle 1-day Acuvue Define (Accent style), or spoke-design circle 1-day Acuvue Define (Vivid style). All of these lenses are made of the same materials and have the same lens parameters, except for the tinted design. HOAs induced by each contact lens were measured for 4- and 6-mm pupils. The coma-like, spherical-like, and total HOAs of each lens type were compared. HOAs of well- and poorly fitting lenses were also compared. For a 4-mm pupil, the HOAs of the three lens types did not differ significantly. For the 6-mm pupil, coma-like and total HOAs were significantly larger with decorative lenses than with clear lenses (P < 0.05, Bonferroni test). No significant differences were observed between the two types of decorative lenses. Poorly fitting decorative lenses showed significantly larger HOAs than did well-fitting decorative lenses. Poorly fitting decorative lenses may reduce the quality of vision. Consequently, care should be taken that these lenses are properly centered.

Aero-optical jitter estimation using higher-order wavefronts

Wavefront measurements from wind tunnel or flight testing of an optical system are affected by jitter sources due to the measurement platform, system vibrations, or aero-mechanical buffeting. Depending on the nature of the testing, the wavefront jitter will be a composite of several effects, one of which is the aero-optical jitter; i.e., the wavefront tilt due to random air density fluctuations. To isolate the aero-optical jitter component from recent testing, we have developed an estimation technique that uses only higher-order wavefront measurements to determine the jitter. By analogy with work done previously with free-stream turbulence, we have developed a minimum mean-square error estimator using higher-order wavefront modes to compute the current-frame tilt components through a linear operation. The estimator is determined from computational fluid dynamics evaluation of aero-optical disturbances, but does not depend on the strength of such disturbances. Applying this technique to turret flight test data, we found aero-optical jitter to be 7.7±0.8 μrad and to scale with (ρ/ρ SL )M 2 (∼1 μrad in the actual test cases examined). The half-power point of the aero-optical jitter variance was found to be ∼2u ∞ /D t and to roll off in temporal frequency with a power law between f −11/3 and f −10/3 .

Dual versus single Scheimpflug camera for anterior segment analysis: Precision and agreement

To assess the repeatability, reproducibility, and agreement of the Pentacam HR single-camera and Galilei G2 dual-camera Scheimpflug devices in anterior segment analysis. Begitek Clínica Oftalmológica, San Sebastián, Spain. Prospective randomized observational study. Healthy young individuals had 3 consecutive tests by 2 examiners. Analyzed parameters were anterior and posterior cornea simulated keratometry (K), K flat, K steep, astigmatism magnitude and axis, J(0) and J(45) vectors, asphericity, total corneal higher-order wavefront aberrations (root mean square [RMS], coma, trefoil, spherical aberration), central cornea and thinnest-point thicknesses, and anterior chamber depth. Repeatability and reproducibility were evaluated by calculating the within-subject standard deviation (S(w)), some derived coefficients, and the intraclass correlation coefficient. Agreement was assessed with the Bland-Altman method. The single-camera device reproducibility (S(w)) was simulated K, 0.04 diopter (D); J(0), 0.03D; J(45), 0.04 D; total power, 0.04 D; spherical aberration, 0.02 μm; higher-order aberrations (HOAs), 0.02μm; central corneal thickness (CCT), 3.39 μm. The dual-camera device S(w) was simulated K, 0.07 D; J(0), 0.13 D; J(45), 0.04 D; total power, 0.08 D; spherical aberration, 0.02 μm; HOAs, 0.11 μm; CCT, 1.36 μm. Agreement was good for most parameters except total corneal power (mean difference 1.58 D ± 0.22 (SD) and HOA RMS (mean difference 0.48 ± 0.19 μm) (both P<.00). Repeatability and reproducibility were good for all parameters. The single-camera device was more precise for curvature, astigmatism, and corneal wavefront error measurements and the dual-camera device for pachymetry measurements. Agreement was good with some relevant exceptions. Dr. Aramberri is consultant to Costruzione Strumenti Oftalmici, Firenze, Italy. No other author has a financial or proprietary interest in any material or method mentioned.

Variations in image optical quality of the eye and the sampling limit of resolution of the cone mosaic with axial length in young adults

To evaluate the variation in higher-order ocular wavefront aberrations and the Nyquist limit of resolution of the cone mosaic (N(c)) in a population of young healthy subjects and the relation to axial length (AL). Fondazione G.B. Bietti IRCCS, Rome, Italy. Case series. An adaptive optics retinal camera prototype (rtx1) was used to image the cone mosaic. Cone density and N(c) were calculated at fixed eccentricity between 260 μm and 600 μm from the foveal center. Ocular higher-order wavefront aberrations were measured using the OPD Scan II device. The coefficient of variation (CoV) was used to analyze the variation in optical and retinal parameters. The correlation of optical and retinal parameters with AL was performed using Pearson analysis. Twelve subjects (age 24 to 38 years; AL 22.61 to 26.63 mm) were evaluated. A high interindividual variation in the higher-order wavefront aberrations was found, ranging from 26% for corneal higher-order aberrations (HOAs) to 41% for intraocular HOAs. The CoV of cone density and N(c) were 16% and 5%, respectively. The decline in cone density and N(c) with AL was statistically significant at all retinal eccentricities (R(2) > 0.44, P<.001). Although there appeared to be random variation in the eye's optical wavefront aberration from subject to subject, the cone-packing density and N(c) were highly correlated with AL. Although the eye's overall image optical quality in the emmetropic group and the myopic group was comparable, the spatial sampling of the cone mosaic decreased with increasing AL. No author has a financial or proprietary interest in any material or method mentioned.

Impact of near-distance computer work on wavefront aberration in different types of myopia

Background Both accommodative abnormality and higher order wavefront aberrations associated with near work are interrelated with blurry retinal image.It is very important to investigate the higher order wavefront aberrations in stable and progressive myopic eyes before and after near work. Objective The present study was to observe the high order aberration change of myopic eyes before and after computer work upon near work stimulation as well as the relationship of high order aberration changes to types of myopia. Methods The case-controlled design was used in this clinical study.Sixty right eyes of 60 subjects were enrolled,including 30 progressive myopias and 30 stable myopias with matched age and gender.Refractive errors of the subjects were completely corrected by the wearing of spectacles.The subjects remained the work for 1 hour in front of a computer monitor with 40 cm distance under the dark environment and nature pupil size,and the height of the eye and monitor center kept the same level.The changes of wavefront aberration in test eyes were measured with Complete Ophthalmic Analysis System before and after 1 hour of continuous computer work.The influences of computer-work and myopia types on wavefront aberration were analyzed in 3,4,5 mm pupil size.Root-mean-square (RMS) of aberrations was calculated as the index of higher order wavefront aberrations. Results There were no significant differences in the higher order wavefront aberrations before and after computer work for the two types of myopic eyes under the 3,4,5 mm pupil.The RMS of higher order wavefront aberrations were similar between progressive myopia and stable myopia under the 3 mm pupil condition.Total higher order RMS,6th-order,5th-order and 3rd-order RMS were significantly higher in progressive myopic group compared with stable myopic group under the 4 mm pupil size ( RMS3:F =5.985,P =0.016 ; RMS5:F =3.975,p=0.049;RMS6:F=8.130,P=0.005:RMST:F=6.493,P=0.012) and 5mm pupil size(RMS3:F=13.132,P=0.000;RMS5:F =4.032,P=0.047 ; RMS6:F =4.393,P=0.038:RMST:F=10.508,P=0.002 ).The spherical aberrations were higher in progressive myopic group under the 3,4,5 mm pupil conditions in comparison with stable myopic group,but these alterations were insignificant between two types of myopias ( P＞0.05 ). Conclusions Higher order wavefront aberrations of progressive myopic eyes is comparable higher than the stable myopic eyes.Computer reading task dose not significantly impact the higher order wavefront aberrations on myopic eyes. Key words: Myopia/progressive, stable; Wavefront aberration; Computer work

Corneal Wavefront Aberrations in Patients Wearing Multifocal Soft Contact Lenses for Myopia Control

Purpose: The purpose of this study was to evaluate the change in corneal wavefront aberrations in young adults who have been fit with multifocal soft contact lenses for myopia progression control. Findings have been analyzed for statistical significance and clinical relevance and compared to reportedly successful Orthokeratology outcomes. Methods: The dominant eye of 40 participants (27 women, 13 men; mean age 27.3 ± 3.2 years; range 23 to 39 years) was fit with Proclear Multifocal center distance lenses (Coopervision, Pleasanton, USA) having a variety of distance powers and reading additions. Refractive errors were limited to a range of –6.00 D up to +1.00 D of sphere, and no greater than –1.00 D of cylinder. Corneal wavefront measurements were performed over 6 mm diameters with a Zeiss Atlas 9000 corneal topographer (Zeiss Meditec, Dublin, USA) prior to, and following lens fitting. Data were converted into rectangular Fourier optics terms M, J0, J45 and RMS values for each reading addition were statistically analyzed. Following evaluation of statistical significance and clinical relevance, results were compared to published data from successful Orthokeratology treatments. Results: Statistically significant changes in higher order aberrations were detected for lenses of all reading additions. Lens groups with higher Add-powers demonstrated stronger changes with increased significance. Final RMS values relating to 2nd, 3rd and 4th Zernike Orders reached clinical significance with a wavefront error of 0.10 μm, the equivalent of 0.25D. Moreover, as Add-powers increased, 3rd and 4th order aberrations likewise showed an increase. Pre-fitting astigmatism values accounted for the highest recorded aberrations and remained predominantly unchanged. Conclusion: Proclear Multifocal center-distance contact lenses were found to increase higher order wavefront aberrations in a manner dependent on their Add-power. In comparison to successful Orthokeratology outcomes, the amounts of resulting aberrations are notably different.

Sources of straylight in the post-focus imaging instrumentation of the Swedish 1-m Solar Telescope

Recently measured straylight PSFs in Hinode/SOT make granulation contrast in observed data and synthetic MHD data consistent. Data from earthbound telescopes also need accurate correction for straylight and fixed optical aberrations. We aim to develop a method for measuring straylight in the post-focus imaging optics of the SST. We removed any influence from atmospheric turbulence and scattering by using an artificial target. We measured integrated straylight from three different sources in the same data: ghost images caused by reflections in the near-detector optics, PSFs corresponding to wavefront aberrations in the optics by using phase diversity, and extended scattering PSF wings of unknown origin by fitting to a number of different kernels. We performed the analysis separately in the red and blue beams. Wavefront aberrations, which possibly originate in the bimorph mirror of the adaptive optics, are responsible for a wavelength-dependent straylight of 20-30% of the intensity in the form of PSFs with 90% of the energy contained within a radius of 0.6". There are ghost images that contribute at the most a few % of straylight. The fraction of other sources of scattered light from the post-focus instrumentation of the SST is only \sim10^-3 of the recorded intensity. This contribution has wide wings with FWHM \sim16" in the blue and \sim34" in the red. The present method seems to work well for separately estimating wavefront aberrations and the scattering kernel shape and fraction. Ghost images can be expected at the same level for solar observations. The high-order wavefront aberrations possibly caused by the AO bimorph mirror dominate the measured straylight but are likely to change when imaging the Sun. We can therefore make no firm statements about the origin of straylight in SST data, but strongly suspect wavefront aberrations to be the dominant source.

64 Symptoms of glare, halo and blur in a European vision-corrected population

Purpose: To investigate the wavefront aberration of a large population of physiologically normal eyes. Method: Subjects participated in a series of studies to investigate the performance of wavefront correcting and wavefront guided LASIK procedures. During pre-operative biometry measurements, a Zywave wavefront sensor was used to measure the lower and higher aberrations of each eye for a 6mm pupil while the subject fixates at infinity. Results: The combined results for this analysis represent the single largest population of wavefront aberration measurements in normal preoperative eyes performed under identical and controlled conditions, with a total sample size of 1333 eyes (1159 myopic and 174 hyperopic). Population age ranged from 19 to 70 years of age. There were 859 Caucasian eyes and 519 Asian eyes and the distribution between males and females was 533 and 742, respectively. A large variation in wavefront aberration was found for 2nd through 5th order Zernike coefficients. Population variation for each Zernike coefficient was centered around zero for all but primary spherical aberration which demonstrated a slightly under-corrected distribution peak with a mean of 0.18 for the myopic eyes and 0.27 for hyperopic eyes. Conclusions: This large sample population study supports previous reports in regards to trends seen with higher order wavefront aberrations and average spherical aberration. However, this study extends these relationships to a sample that can be subdivided into age, race, gender and aemetropia to study relationships between these variables. Contact lenses designed to correct the spherical aberration in the human eye may benefit from examination of these sub groups.

Customized Photorefractive Keratectomy for the Correction of Regular and Irregular Astigmatism After Penetrating Keratoplasty

To report visual, wavefront, and topographic outcomes in 5 post-penetrating keratoplasty patients who underwent customized aspheric topography-guided photorefractive keratectomy for high astigmatism or severe higher-order aberrations. A chart review was performed for data collection. The custom aspheric transition zone ablation algorithm (CATz) with the CX III excimer was used for all treatments. Ablations were calculated based on corneal elevation data. Phototherapeutic keratectomy was the first step of the procedure. Visual acuity, corneal higher-order wavefront aberrations (Zernike sixth order and 4-mm diameter), corneal topography, and patient satisfaction were evaluated preoperatively and at the last visit postoperatively (range, 3 months to 4.5 years). The paired t test was used for statistical comparison of higher-order aberrations, with P < 0.05 indicating statistical significance. The mean spherical equivalent was -4.50 diopters (D) (range, -9.50 to +3.25 D) preoperatively and -1.00 D (range, -3.25 to +0.25 D) at the final visit. The mean cylinder was -7.00 D (range, -4.75 to -9.00 D) preoperatively and -1.25 D (range, -0.50 to -2.50 D) postoperatively. Postoperative uncorrected distance visual acuity increased in all eyes. No eyes lost corrected distance visual acuity postoperatively. There was a statistically significant decrease in higher-order corneal spherical aberration postoperatively (P = 0.02). Four patients were "very satisfied" or "satisfied" with the postoperative outcome, and 1 patient was "somewhat satisfied". All patients reported reduced symptoms postoperatively. Phototherapeutic keratectomy with CATz was effective as a single-step treatment for severe higher-order aberrations or moderate astigmatism after penetrating keratoplasty.

Experimental investigation of segmented adaptive optics for spatial laser array in an atmospheric turbulence condition

We describe a concept of using segmented adaptive optics (AO) to correct the higher-order wavefront aberrations (HOWAs) in an atmospheric turbulence condition. The effects of piston and tip-tilt corrections are analyzed by numerical simulation. An experiment test-bed is built for verification. Seven spatial beamlets are combined into a hexagonal array by use of a pyramid, and an active segmented mirror is used for phase modulation. The AO control is implemented by stochastic parallel gradient descent (SPGD) algorithm. Experimentally, after segmented AO is enabled, the HOWA in warmed air environment has been effectively corrected and the peak intensity of far-field has been enhanced by 5 times.

Optical Performance of the Cornea Six Years following Photorefractive Keratectomy for Myopia

To investigate the optical quality of the anterior cornea during a 6-year follow-up after photorefractive keratectomy (PRK) for myopia. Forty-nine patients (98 eyes) underwent PRK using an excimer laser platform. Patients were subdivided into three groups according to their preoperative spherical equivalent refraction and amount of cylinder component: the low-myopia, the high-myopia, and the astigmatism group. Preoperative and 1-, 3-, and 6-year postoperative root-mean-square values of coma, spherical aberration (SA), and total high-order aberrations (HOA) were calculated over 3.50- and 6.00-mm pupil diameters. Modulation transfer function (MTF) values and point spread functions were calculated to describe the impact of myopic PRK on the optical performance of the cornea during follow-up. The amount of postoperative SA was higher (P < 0.05) than the preoperative state in both the low- and the high-myopia groups over 3.50- and 6.00-mm pupil sizes. The postoperative increase of coma was statistically significant (P < 0.05) only in the high-myopia group over both pupil sizes. Total-HOA increased (P < 0.05) after PRK in all the study groups over 6.00-mm pupil. A distinct increase in the ratios of MTF was calculated over 6.00-mm pupil, at low and middle spatial frequencies in the range between 5 and 15 cyc/deg, especially after the deepest myopic ablations. The high-order wavefront aberration of the anterior cornea stabilized 1-year after PRK for the treatment of myopia up to -9.00 D. The effect of induced HOA on the image optical quality of the cornea was increased mainly after the correction of high myopia over scotopic pupil.

The Impact of the Boston Ocular Surface Prosthesis on Wavefront Higher-Order Aberrations

To evaluate the effect of the Boston Ocular Surface Prosthesis (Boston Foundation for Sight) on higher-order wavefront aberrations in eyes with keratoconus, eyes that have undergone penetrating keratoplasty, eyes that have undergone refractive surgery, and eyes with ocular surface diseases. Prospective, clinical study. The study evaluated 56 eyes of 39 patients with irregular astigmatism who were treated with the Boston Ocular Surface Prosthesis when conventional treatments failed. Patients were sorted into 4 clinical groups based on the underlying cause of irregular astigmatism, including keratoconus (group 1), post-penetrating keratoplasty (group 2), post-refractive surgery (group 3), and ocular surface diseases (group 4). Another 6 eyes of 5 patients who were treated with rigid gas permeable lenses also were evaluated. Best-corrected visual acuity; topographic refractive indices, including spherical, cylindrical, spherical equivalent values; and higher-order and total wavefront aberration errors were noted at baseline and after fitting the lens. In all groups, higher-order wavefront aberration error was noted to decrease significantly in eyes wearing the Boston Ocular Surface Prosthesis (P<.001, P=.001, P=.002, and P=.001, respectively). By post hoc analysis, significant differences in the level of higher-order aberrations were observed only between groups 1 and 4 (P=.012) and groups 1 and 2 (P=.033). In the overall group, mean correction rate of higher-order aberration error with the Boston Ocular Surface Prosthesis was 72.3%. However, in eyes with rigid gas permeable lenses, 2 eyes demonstrated increased higher-order aberration error, whereas the mean correction rate in other 4 eyes was only 42.5%. With its unique structure, the Boston Ocular Surface Prosthesis was found to be very effective in reducing higher-order wavefront aberrations in patients with irregular astigmatism resulting from a number of corneal and ocular surface conditions who had not responded satisfactorily to conventional methods of optical correction.

Postoperative wavefront analysis and contrast sensitivity of the multifocal RestorTM IOL versus the AcrylisaTM IOL

Abstract Purpose To compare visual acuity, total and high order wavefront aberrations (coma, spherical aberration, and other terms of high order aberration), and contrast sensitivity in eyes implanted with the multifocal Restore IOL versus the multifocal Acrylisa IOL. Methods Patients were divided in two groups: group 1 (8 patients, 16 eyes implanted with Restor) and group 2 (15 patients / 30 eyes implanted with Acrylisa). All eyes were targeted for emmetropia. Complete ophthalmological examination, including uncorrected visual acuity (UCVA), best spectacle‐corrected visual acuity (BSCVA) was performed. Contrast sensitivity evaluation,and wavefront analysis, were performed with the Imagine Eyes IRX3 wavefront aberrometer. Measurements with the IRX3 were performed in triplicate in order to verify the robustness of the data. Results All eyes in all groups had BSCVA &gt; or = 20/20 postoperatively. Measurements with the IRX3 were easily obtained. The triplicate measurements confirmed the robustness of the data. Mean total aberration root‐mean‐square (RMS) values and higher order aberrations (HOA) value were not significantly different between the two groups. Residual spherical aberration values were comparable in both groups and appeared inferior if to the ones previously obtained with non aspheric standard monofocal IOLs. Mean contrast sensitivity values were comparable in both groups. Conclusion The measurement of higher order aberrations in patients implanted with multifocal IOLs is easy and reproducible with the IRX3. There is no statistical difference between the values obtained in the 2 groups regarding RMS and HOA. Contrast sensitivity revealed similar values in both groups.

Progress of research in relationship between high order wavefront aberration and accommodation of human eye

Wavefront aberration technique is an important objective criterion to evaluate the optical quality of human eye. Higher order wavefront aberrations and accommodation affect each other, influencing retinal image quality of the human eye which is a dynamic optic system. Investigation of the interaction between these two factors helps in revealing reasonable explanation for visual symptoms. This paper reviewed higher order aberrations related points such as their clue for accommodation, changes related with accommodation, microfluctuations during accommodative relaxation, and accommodation related higher order aberrations changes in myopia.

Repeatability of corneal power and wavefront aberration measurements with a dual-Scheimpflug Placido corneal topographer

To evaluate the repeatability of the Galilei dual-Scheimpflug analyzer in measuring corneal curvature, wavefront aberrations, pachymetry, and anterior chamber depth (ACD). Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Three consecutive measurements were performed in 1 eye of each subject. The following were evaluated: (1) mean total corneal power at the central, paracentral, and peripheral zones (0.0 to 4.0 mm, 4.0 to 7.0 mm, and 7.0 to 8.0 mm, respectively) and posterior corneal power (K(avg)); (2) corneal higher-order wavefront aberrations (6.0 mm pupil); (3) mean pachymetry at the central, paracentral, and peripheral zones; and (4) ACD. Repeatability was assessed by calculating the within-subject standard deviation (SD), coefficient of variation (COV), and intraclass correlation coefficient (ICC). The study enrolled 20 subjects. The SD was 0.09 diopter (D), 0.05 D, and 0.19 D for central, paracentral, and peripheral total corneal power, respectively, and 0.03 D for posterior K(avg). The COV ranged from 0.10% to 0.35%, and the ICC was 0.996 or more (P<.001). For 3rd-order coma and trefoil, the SD was 0.08 mum and 0.09 mum, respectively. For 4th-order spherical aberration, astigmatism, and tetrafoil, the SDs were lower (0.02 mum, 0.04 mum, and 0.09 mum, respectively). The SD was 1.68 mum, 1.98 mum, and 2.82 mum for central, paracentral, and peripheral pachymetry, respectively, and 0.04 mm for ACD. Dual-Scheimpflug measurements of corneal power, pachymetry, ACD, and corneal aberrations for Zernike terms in the middle of the Zernike tree showed excellent repeatability.

Effects of Amount of Myopic Correction on Long-term Changes in Higher-order Wavefront Aberrations in ASA-PRK

Purpose: To evaluate the effects of the amount of myopic correction on long-term changes in higher-order wavefront aberrations (HOAs) in advanced surface ablation-photorefractive keratectomy (ASA-PRK). Methods: The 193 eyes of 101 patients who underwent ASA-PRK were divided into two groups according to the amount of myopic correction by the median value (Group 1 -4.37D, 97 eyes, mean -3.26 0.77D; Group 2 > -4.37D, 96 eyes, mean -5.77 1.00D). Wavefront aberrometry was performed to measure total HOA, coma, trefoil, and spherical aberration preoperatively and at 1, 3, 6, 12, and 24 months after ASA-PRK. Statistical analysis was performed to compare changes in all HOAs between the two groups. Results: Each magnitude of total HOA, coma, and spherical aberration except trefoil significantly increased at 1, 3, 6, 12, and 24 months postoperatively in each group (p -4.37D). Increases in ASA-PRK-induced HOAs primarily originated from short-term changes in the postoperative one-month period and did not return to the preoperative level during the postoperative two-year period.

Influence of induced decentered orthokeratology lens on ocular higher-order wavefront aberrations and contrast sensitivity function

To quantitatively evaluate the effect of overnight orthokeratology lenses intentionally left decentered after 3 months of wear and assess the influence on clinical outcomes such as ocular higher-order wavefront aberrations and contrast sensitivity function. Department of Ophthalmology, Tsukuba University Hospital, Ibaraki, Japan. This prospective study assessed refraction, visual acuity, corneal topography, wavefront aberration, and contrast sensitivity function before and 3 months after overnight orthokeratology treatment. Decentration of the treatment zone from the center of the entrance pupil was determined using computerized videokeratography (TMS-4) and data-analysis software (MatLab). The relationship between decentration and the clinical parameters was analyzed. The mean age of the 23 patients (46 eyes) was 24.2 years+/-3.3 (SD) and the mean spherical equivalent refraction before treatment, -2.38+/-0.98 diopters. The mean magnitude of decentration (0.85+/-0.51 mm) was statistically significantly correlated with the amount of myopic correction (P<.05), increases in coma-like aberration (P<.01), increases in spherical-like aberration (P<.01), and reductions in contrast sensitivity function (P<.0001). Changes in contrast sensitivity function were also statistically significantly correlated with the amount of myopic correction (P<.05), changes in coma-like aberration (P<.01), and changes in spherical-like aberration (P<.01). Stepwise multiple regression analysis showed that the magnitude of decentration was the only explanatory variable related to contrast sensitivity function (P<.0001). Decentered treatment of orthokeratology resulted in decreased contrast sensitivity after treatment, showing that centration of the procedure is crucial to good outcomes.

OCULAR WAVEFRONT ABERRATIONS IN PATIENTS WITH MACULAR DISEASES

There have been reports that by compensating for ocular aberrations using adaptive optical systems it may be possible to improve the resolution of clinical retinal imaging systems beyond what is now possible. To develop such a system to observe eyes with retinal disease, understanding of ocular wavefront aberrations in individuals with retinal disease is required. Eighty-two eyes of 66 patients with macular disease (epiretinal membrane, macular edema, macular hole, etc.) and 85 eyes of 51 patients without retinal disease were studied. Using a ray-tracing wavefront device, each eye was scanned at both small and large pupil apertures, and Zernike coefficients up to the sixth order were acquired. In phakic eyes, third-order root mean square errors in the macular disease group were statistically greater than in the control group, an average of 12% for 5-mm and 31% for 3-mm scan diameters (P < 0.021). In pseudophakic eyes, there was also an elevation of third-order root mean square, on average 57% for 5-mm and 51% for 3-mm scan diameters (P < 0.031). Higher-order wavefront aberrations in eyes with macular disease were greater than in control eyes without disease. This study suggests that such aberrations may result from irregular or multiple reflecting retinal surfaces. Modifications in wavefront sensor technology will be needed to accurately determine wavefront aberration and allow correction using adaptive optics in eyes with macular irregularities.