Higher-order Wavefront Aberrations Research Articles

Современные подходы к хирургии катаракт с высокой остротой зрения на основании анализа волнового фронта

Relevance. Until recently, visual acuity was the main criterion for determining the timing of surgery, but already in the early stages of cataract development, patients may suffer from reduced image quality, which affects the quality of life (“night” myopia, light scattering, blurring). Deterioration in visual function in these patients may be explained by refractive errors. Analysis of internal higher-order aberrations resulting from slight opacification of the lens is important for determining the effect of media opacity on wavefront aberrations (WF) and for determining the indications and timing of surgical treatment, especially in patients with high visual acuity. Purpose. Evaluate the optical system of the eye with initial cataracts and high visual acuity. Evaluate the wavefront and its aberrations, contrast sensitivity and Shtrel coefficient. Material and methods. The study included 111 eyes with cataracts and 42 eyes without signs of cataracts (control group). Patients aged on average 57±5.3 years. Wavefront analysis was performed using an iTrace ray tracing aberrometer (Tracey Tech., USA) in a dark room under maximum drug-induced mydriasis. In each group, total, corneal, and internal wavefront aberrations were measured at a pupil diameter of 6.0 mm. Higher order aberrations were analyzed using Zernike polynomials (3rd to 5th order). The modulation transfer function (MTF) at different spatial frequencies (0–30 c/deg) and the Strehl coefficient in patients in the study groups were also assessed. Results. Total and internal higher-order wavefront aberrations were significant in different cataract groups compared with control patients, while higher-order corneal aberrations were not statistically different. We noted a higher level of total and internal aberrations in the group of patients with posterior subcapsular cataract. In this regard, patients with posterior subcapsular cataract require surgical treatment at an earlier stage, despite high visual acuity. Conclusion. We recommend assessing the optical quality of vision and wavefront aberrations when observing early cataracts in order to decide whether to perform surgery at an earlier date. Key words: initial cataract, quality of vision, higher order aberrations, internal wavefront aberrations

Two-Dimensional Peripheral Refraction and Higher-Order Wavefront Aberrations Induced by Orthokeratology Lenses Decentration.

The purpose of this study was to explore two-dimensional peripheral refraction and higher-order aberrations (HOAs) induced by orthokeratology lens decentration. Two-dimensional peripheral refraction and HOAs in a rectangular field (horizontally 60 degrees and vertically 36 degrees) were obtained using an open-view Hartmann-Shack wavefront sensor. The peripheral field was divided into 8 regions according to a combination of superior (UZ) or inferior (LZ) and a value, 1 (T25 to T30), 2 (T20 to T25), 3 (N20 to N25), or 4 (N25 to N30). The decentration of the lens was evaluated based on the change of power in the front of the tangential corneal map. All measurements were taken at the baseline and 1 month after lens fitting. In total, 134 myopic children (age = 12.47 ± 1.70 years, SER = -2.44 ± 1.10 diopters [D]) were recruited. In general, horizontally asymmetrical change was observed in relative peripheral refraction (RPR), spherical aberration (SA), and horizontal coma. The root-mean square of higher order aberration (RMSHOA) and vertical coma demonstrated radial symmetrical change and vertically asymmetric change, respectively. Relative peripheral myopia was significantly increased after the treatment, with more myopic refraction in the temporal side. RPR changes in UZ2, UZ3, UZ4, LZ1, and LZ2 were related to the amount of lens decentration (r ≈ 0.4, P<0.05). All HOAs increased after lens fitting (around 0.03 um, 0.02 um, 0.04 um, and 0.41 um for SA, horizontal COMA, vertical COMA, and RMSHOA in the periphery region). RPR and HOAs are related to lens decentration, which might contribute to the efficacy of orthokeratology. The study found a decentration-related optical feature after 1 month of lens wear, which is a suggested protective factor in myopia treatment. The findings might provide new insights for customized contact lens myopia treatment based on optics.

Comparative Analysis of the Effect of Cutting Piezoelectric Ceramics on Optically Oriented Compensation Capability

In a photoelectric tracking system, a deformable mirror can be used to adjust the transmission path of a light beam to achieve accurate measurement and tracking of the target position. The single-piezoelectric-sheet deformable mirror is a commonly used wavefront correction device with outstanding advantages, such as its simple structure, low cost, and easy preparation. However, it usually has a large cross-linking value and a weak ability to correct higher-order wavefront aberrations. To solve this problem, a novel single-piezoelectric-sheet deformable mirror driving structure is proposed in this paper, in which the coupling between the driving units is weakened by laser cutting the piezoelectric ceramics along the electrode gaps to reduce the cross-linking value of the deformable mirror. In order to verify the effectiveness of this driving structure, this paper takes the 85-unit single-piezoelectric-sheet deformable mirror as an example and simulates the influence function for different cutting depth conditions. The simulation results show that the cross-linking value between neighboring drive units decreases significantly as the piezoelectric-ceramic-laser cutting depth of the drive electrode gap increases. When the piezoelectric ceramic was laser cut to a depth of half of the overall thickness, the cross-linking value decreased by 6.8%.

Современные подходы к хирургии катаракты на основании анализа волнового фронта

Relevance. Cataract is the leading cause of visual impairment worldwide. Even in the early stages of cataract development, when the maximum visual acuity often remains high, patients complain of a decrease in image quality (light scattering, diplopia), which is expressed in the difficulty of performing daily and professional activities. The cause of this condition in most cases is internal aberrations of a higher order. One of the topical issues of modern ophthalmology is the definition of indications for surgery of primary cataracts with high visual acuity. Purpose. The purpose of this literature review was to describe the current state of the problem of wavefront changes in patients with various types of initial lens opacity. Material and methods. A systematic analysis of scientific publications of domestic and foreign authors on the resources PubMed, Medline from 2000 to 2022, devoted to the currently existing methods for assessing the quality of vision of patients with initial opacification of the lens, was carried out. Results. Our literature review showed the great importance of assessing wavefront aberrations in patients with initial cataracts and high visual acuity. With the advent of modern diagnostic systems – aberrometers with the possibility of an isolated assessment of internal aberrations, doctors have the opportunity to interpret data on the effect of lens changes on the quality of vision. Conclusion. Visual acuity in patients with initial cataract is not a unique evaluation criterion for determining the timing of surgical intervention. Analysis of wavefront aberrations to a greater extent describe visual impairments and can be used as objective criteria for prescribing surgical treatment. The study of aberrations of the human eye makes it possible to give an objective and quantitative assessment of the optical functions of the eye, which expands the possibilities for diagnosis and for the formation of surgical approaches for initial lens opacities in patients with high visual acuity. Key words: higher-order wavefront aberrations, cataract

Fast estimation method of optimal modal gain for adaptive optical system

In an adaptive optical system, the optimal modal control method refers to applying proportional integral control of different bandwidths to the wavefront aberrations after modal decomposition to achieve better closed-loop results than the unified bandwidth modal control. The optimal modal gain usually needs to be obtained by ergodic solution based on the transfer function model of the adaptive optical system, the measured disturbance power spectral density, and the noise power spectral density, which usually takes a long time. Owing to the time-varying statistical characteristics of atmospheric turbulence, it is difficult to ensure the timeliness of the optimal modal gain. Therefore, we propose a method of fast estimating optimal modal gain based on quadratic polynomial fitting. In the method, it is only necessary to choose three reasonable gain coefficients and calculate their corresponding closed-loop residual errors respectively in order to estimate the optimal gain of single mode. The simulated slope data used in this work are cited from Lijiang 1.8 m adaptive telescope system, which consists of a 241-unit deformable secondary mirror and a Shaker-Hartmann wavefront sensor with 192 sub-apertures, with the first 135-order modes corrected by modal method. Our experiment is to test directly on-line on this system. The results show that under the same atmospheric environment, the proposed method can accurately estimate the optimal modal gain in a very short time and effectively suppress the high-order wavefront aberration. At the same time, owing to the reduced time complexity of the algorithm, the improved optimal modal gain estimation method takes only 0.33 s. Comparatively, it will take 7.08 s to obtain the optimal modal gain coefficient by using the parameter traversal method. Therefore the time spent on obtaining the optimal modal gain is shortened by about 95.3%, which is easier to meet the real-time requirements of the telescope, and beneficial to the adaptive optics system with more high-order modes. For the future adaptive optics system with more than one-thousand units, the proposed method can update the optimal gain to the second level, while the traversal method can only reach the minute level.

Changes of the effective optical zone after small-incision lenticule extraction and a correlation analysis.

The objective of the study is to observe the changes in the effective optical zone (EOZ) after small incision lenticule extraction (SMILE) and explore possible correlations with some influencing factors. In total, 133 eyes after SMILE were divided into the mild to moderate myopia group (- 1.75 D to - 5.75 D, 70 eyes) and the high myopia group (- 6.00 D to - 9.50 D, 63 eyes). The postoperative EOZ was calculated by utilizing the corneal tangential curvature map. Changes in EOZ (△-OZ) were monitored and compared between the two groups. Pearson correlation analysis was conducted to determine the correlation between △-OZ and corneal high-order wavefront aberrations. Multicollinearity analysis and ridge regression analysis were performed to assess the correlation between △-OZ and some corneal parameters. After SMILE, the horizontal EOZ (H-EOZ), vertical EOZ (V-EOZ), and average EOZ (A-EOZ) were significantly smaller than the programmed optical zone (POZ) in both groups (p < 0.05). The difference between V-EOZ and POZ (△V-OZ) and the difference between A-EOZ and POZ (△A-OZ) showed more significant changes in the high myopia group than in the mild to moderate myopia group, and △V-OZ was significantly larger than the difference between H-EOZ and POZ (△H-OZ) in the high myopia group. In both groups, the total high-order aberration (T-HOA) and spherical aberration (SA) both increased after SMILE, and they had a similar significant negative correlation with A-EOZ. Moreover, there was a significant negative correlation between △-OZ and Km (X1), Q-value (X2), spherical equivalent (SE, X3), ablating depth (AD, X4) and △e (X6), and a significant positive correlation between △-OZ and △Q (X5). △H-OZ was expressed as Y1, △V-OZ as Y2, and △A-OZ as Y3. The multiple linear regression equations were as follows: Y1 = 3.683 - 0.065X1, Y2 = 1.549 - 0.469X2 - 0.059X3, Y3 = 4.015 - 0.07X1 - 0.03X3, Y1 = 1.337 - 0.005X4 + 0.413X5, Y2 = 1.265 + 0.469X5, and Y3 = 0.852 - 0.002X4 - 0.398X6. The correlation degree with △A-OZ was ranked as Km > △Q > Q-value > AD > e-value > △e > SE > △Km, as represented by the ridge regression analysis. The EOZ was irregularly reduced after SMILE, which should be taken into consideration in the design of POZ, especially for high myopia. Consideration of the refractive diopter and corneal topography is advised for the design of POZ, the latter of which has greater reference significance.

Implementation of a dark zone maintenance algorithm for speckle drift correction in a high contrast space coronagraph

Due to the limited number of photons, directly imaging planets requires long integration times with a coronagraphic instrument. The wavefront must be stable on the same time scale, which is often difficult in space due to time-varying wavefront errors from thermal gradients and other mechanical instabilities. We discuss a laboratory demonstration of a photon-efficient dark zone maintenance (DZM) algorithm in the presence of representative wavefront error drifts. The DZM algorithm allows for simultaneous estimation and control while obtaining science images and removes the necessity of slewing to a reference star to regenerate the dark zone mid-observation of a target. The experiments are performed on the high-contrast imager for complex aperture telescopes at the Space Telescope Science Institute. The testbed contains an IrisAO segmented primary surrogate, a pair of continuous Boston Micromachine (BMC) kilo deformable mirrors (DMs), and a Lyot coronagraph. Both types of DMs are used to inject synthetic high-order wavefront aberration drifts into the system, possibly similar to those that would occur on telescope optics in a space observatory, which are then corrected by the BMC DMs via the DZM algorithm. In the presence of BMC, IrisAO, and all DM wavefront error drift, we demonstrate maintenance of the dark zone contrast (5.8 − 9.8 λ / Dlyot) at monochromatic levels of 8.5 × 10 − 8, 2.5 × 10 − 8, and 5.9 × 10 − 8, respectively. In addition, we show multiwavelength maintenance at a contrast of 7.0 × 10 − 7 over a 3% band centered at 650 nm (BMC drift). We demonstrate the potential of adaptive wavefront maintenance methods for future exoplanet imaging missions, and our demonstration significantly advances their readiness.

Differences in Image Quality after Three Laser Keratorefractive Procedures for Myopia.

Psychophysical estimates of spatial and depth vision have been shown to be better after bilateral ReLEx small-incision lenticule extraction (SMILE) refractive surgery for myopia, relative to photorefractive keratectomy (PRK) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). The present study provides the optical basis for these findings using computational image quality analysis. This study aimed to compare longitudinal changes in higher-order wavefront aberrations and image quality before and after bilateral PRK, FS-LASIK, and SMILE refractive procedures for correcting myopia. Wavefront aberrations and image quality of both the eyes of 106 subjects (n = 40 for FS-LASIK and SMILE and n = 26 for PRK) were determined pre-operatively and at 1-week, 1-month, 3-month, and 6-month post-operative intervals using computational through-focus analysis for a 6-mm pupil diameter. Image quality was quantified in terms of its peak value and its interocular difference, residual defocus that was needed to achieve peak image quality (best focus), and the depth of focus. The increase in root mean squared deviations of higher-order aberrations post-operatively was lesser after SMILE (1-month visit median [25th to 75th interquartile range], 0.34 μm (0.28 to 0.39 μm]) than after PRK (0.80 μm [0.74 to 0.87 μm]) and FS-LASIK (0.74 μm [0.59 to 0.83 μm]; P ≤ .001), all relative to pre-operative values (0.20 μm [0.15 to 0.30 μm]). The peak image quality dropped and its interocular difference increased, best focus shifted myopically by 0.5 to 0.75 D, and depth of focus widened significantly after PRK and FS-LASIK surgeries, all relative to pre-operative values (P < .001). All these changes were negligible but statistically significant in a minority of instances after SMILE surgery (P ≥ .01). Although all three refractive surgeries correct myopia, the image quality and its similarity between eyes are better and closer to pre-operative values after SMILE, compared with FS-LASIK and PRK. These results can be explained from the underlying increase in higher-order wavefront aberrations experienced by the eye post-operatively.

How Contact Lenses Have Influenced Research Developments in Optics and Vision Science

Initially, contact lenses were developed as the only viable option to provide improved vision for patients suffering from conditions which distortedthe corneal surface in an irregular fashion, rendering spectacle correction an unsatisfactory option. Developments in materials, fitting methods andmanufacturing technologies soon made contact lenses an appealing option for all spectacle wearers, particularly with the development of toricand multifocal lens options. Although the optical challenges of contact lenses appeared to be relatively straightforward in their early years, thedevelopment of improved in-vivo diagnostic and in-vitro metrology instrumentation led to a significantly greater understanding of the nature of theoptical errors (e.g. higher order wavefront aberrations) of the eye and contact lenses and the interactions between them when worn. The featuresof contact lenses having extremely steep curvatures and being aligned closely to the eye’s visual axis in all positions of gaze provide both uniquechallenges and opportunities for improving the visual performance of both physiological and pathological eyes, and have guided the efforts ofsignificant vison science research in more recent times.

Comparison of the optical quality after SMILE and FS-LASIK for high myopia by OQAS and iTrace analyzer: a one-year retrospective study

BackgroundTo compare the correction effect and optical quality after small-incision lenticule extraction (SMILE) and femtosecond laser assisted laser in situ keratomileusis (FS-LASIK) for high myopia.Methods51 high myopia eyes after SMILE and 49 high myopia eyes after FS-LASIK were enrolled and divided into two groups retrospectively. The OQAS and iTrace analyzer were used for optical quality inspection. Between the two groups the spherical equivalent (SE), astigmatism, uncorrected distant visual acuity (UDVA), strehl ratio (SR), modulation transfer function cutoff frequency (MTF cutoff), objective scatter index (OSI) and wavefront aberrations were analyzed and compared before surgery and at 1, 6 and 12 months after surgery.ResultsAfter the operation: (1) SE and astigmatism declined and UDVA increased significantly in both groups, and UDVA was better after SMILE than FS-LASIK. (2) SR and MTF cutoff reduced and OSI increased significantly after SMILE and FS-LASIK. SR and MTF cutoff were significantly higher after SMILE than FS-LASIK. OSI was significantly lower after SMILE than FS-LASIK. (3) The total wavefront aberration, total low-order wavefront aberration, defocus and astigmatism aberration as well as trefoil aberration reduced significantly in both groups. The total high-order wavefront aberration increased significantly after FS-LASIK. The spherical and coma aberration increased significantly in both groups. The total high-order wavefront aberration and coma aberration at 1 month were higher after FS-LASIK than SMILE.ConclusionThe optical quality descended after SMILE and FS-LASIK. SMILE was superior to FS-LASIK at the correction effect and optical quality for high myopia. The combination of OQAS and iTrace analyzer is a valuable complementary measurement in evaluating the optical quality after the refractive surgery.Trial registrationThis is a retrospective study. This research was approved by the ethics committee of Xiangya Hospital and the IRB approval number is 201612074.

Correlation of accommodation and lens location with higher-order aberrations and axial length elongation during orthokeratology lens wear

This study examined the effects of overnight orthokeratology (OK) on higher-order wavefront aberrations (HOA), axial length elongation, and accommodation. Low to moderate myopic subjects with healthy eyes wore OK lenses nightly for 9 months. Corneal topography wavefront aberrations and accommodation were measured approximately monthly. Linear mixed-effects models were used to examine the association between the change in peripheral corneal parameters relative to the central cornea with HOA, and the association of accommodation and axial length elongation with HOA. Thirty-three participants (mean age 19.61 years) were included. Mean baseline refraction was −2.97 D (range, −1.0 to −5.0 D). The level of spherical aberration (SA) was associated with a change in relative superior-central corneal thickness (β = −0.21, SE = 0.10, p < 0.037) and with the increased difference in superior-central corneal curvature (β = 0.34, SE = 0.15, p = 0.026). The change of coma increased with the change in relative superior corneal curvature (β = 0.84, SE = 0.18, p < 0.001). Axial length elongation was associated with both horizontal coma (β = 0.19, SE = 0.07, p = 0.018) and SA (β = 0.20, SE = 0.07, p = 0.003). While accommodation and axial length were correlated with HOA, axial length elongation was not correlated with accommodation in OK lens wearers.

High-order wavefront aberrations due to a laser-induced breakdown spark in still air.

Experimental measurements of the wavefronts of the light from a laser-induced breakdown (LIB) spark in stationary air are presented for the full range of angles between the LIB laser and wavefront sensor up to 90°. The wavefront data are compared to measurements of the spark shape and position acquired from simultaneous photographic images of the spark. The results show that the aberrations from the LIB spark appear primarily as two modes determined from proper orthogonal decomposition, with the amplitude and importance of the modes depending on system parameters and viewing angle. Data are also presented demonstrating the link between the spark wavefront and the spark shape, and conclusions are drawn regarding how to minimize the spark aberrations for optical systems in which the spark is used as a light source to measure optical wavefronts.

Longitudinal Changes in Optical Quality, Spatial Vision, and Depth Vision after Laser Refractive Surgery for Myopia.

Laser refractive surgery procedures are efficacious at correcting myopia, but they result in long-term deterioration of optical quality that affects monocular and binocular visual performance. The study shows that the optical quality of the two eyes needs to be similar to optimize binocular visual performance after surgery. This study aimed to systematically analyze longitudinal changes in optical quality, high- and low-contrast logMAR acuity and random-dot stereoacuity before and after three refractive surgery procedures for correcting myopia. A total of 106 subjects (laser-assisted in situ keratomileusis, 40; photorefractive keratectomy, 26; small-incision lenticule extraction, 40) with myopia and astigmatism ≤1.5 D participated in this prospective cohort-based study. All aforementioned outcome variables were measured in both eyes pre-operatively and 1 week and 1, 3, and 6 months post-operatively. Pre-operative myopic spherical equivalent of refraction (median [25th to 75th interquartile range], -6.4 D [-8.0 to -4.2 D] for laser-assisted in situ keratomileusis, -4.3 D [-5.0 to -3.5 D] for photorefractive keratectomy, -5.5 D [-6.5 to -4.3 D] for small-incision lenticule extraction) was corrected to within ±0.75 D of emmetropia in all cohorts up to 6 months post-operatively (P < .001). Higher-order wavefront aberrations, uncorrected high- and low-contrast logMAR acuity, and stereoacuity all worsened and remained so up to 6 months post-operatively, relative to pre-operative values (P < .001). Stereoacuity worsened with both interocular average and difference in the magnitude of higher-order aberrations, whereas logMAR acuities worsened only with interocular average of these aberrations (r ≥ 0.40; P < .01 for all). Although the refractive surgery procedures tested here correct myopia, they result in a sustained (up to 6 months) loss of optical quality and spatial and depth-related visual functions post-operatively. Both interocular average and difference in the eye's optical quality seem to impair binocular visual functions after refractive surgery for myopia.

Do visual performance and optical quality vary across different contact lens correction modalities in keratoconus?

PurposeWhile several advanced contact lens (CL) designs are commercially available for vision correction in keratoconus, their visual performance and optical quality, relative to each other and controls remains unclear. This prospective, crossover study tested the hypothesis that these CL designs would have a differential impact on visual performance and optical quality in subjects with advanced keratoconus, but not in early to moderate disease states. MethodsSpatial vision (logMAR acuity and contrast sensitivity), depth vision (stereoacuity) and optical quality (higher-order wavefront aberrations) were measured on 28 bilaterally mild to advanced keratoconics (age: 20–28yrs; 15 males), novice to CL wear, and in 10 age-matched controls using well-established psychophysical and aberrometry techniques. All data were collected on keratoconic subjects with their spectacles and with conventional RGP, Kerasoft®, Rose K2® and Scleral RGP® CL’s in randomized order, atleast a week apart from each other. ResultsAll outcome variables deteriorated with keratoconus severity and improved with CL wear, relative to spectacles (p < 0.05). This improvement was smaller for Kerasoft CL (p < 0.05) and higher but comparable for the other three CL designs (p = 0.3), across all disease severity. Visual functions and optical quality outcomes never reached control levels for any correction modality (p < 0.05). ConclusionVisual performance and optical quality in keratoconus does not appear to improve commensurately with the sophistication of CL design across disease severity. Non-visual factors like quality of CL fit, wearing comfort and cost may therefore drive the choice of CL dispensed in keratoconus more than the performance efficacy of these lenses.

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Performance improvement of free-space continuous-variable quantum key distribution with an adaptive optics unit

We propose a method to enhance the performance of the free-space continuous-variable quantum key distribution (FSCVQKD) by utilizing an adaptive optics (AO) unit at the receiver’s side to suppress wavefront distortions caused by high-order wavefront aberrations for fault-tolerant detection. Benefiting from the AO unit, the high-order wavefront aberrations can be corrected and thus effectively improve the mixing efficiency of homodyne detection, which enhances the performance of FSCVQKD. Considering the fact that the closed-loop control bandwidth of AO unit and the atmospheric coherence length have an important effect in performance improvement for FSCVQKD, in this paper, we analyze the performance of our protocol with AO unit under different closed-loop control bandwidths and atmospheric coherence lengths, respectively. The analysis is performed by considering the three specific scenarios of turbulence which are frequent challenges in FSCVQKD protocol, namely beam wandering, randomly blocked and log-normal distribution. In addition, we also study the impact of AO-added noise on our protocol. Simulation results show that all in the beam wandering case, the randomly blocked case and the log-normal distribution, the use of AO unit can enhance the performance of FSCVQKD protocol by adjusting the closed-loop control bandwidth of AO unit and the atmospheric coherence length in appropriate ranges with the case of fixed Greenwood frequency in the presence of AO-added noise.

High-order wavefront aberration measurement method for hyper-NA lithographic projection lens based on a binary target and rotated regression matrix

Abstract A high-order wavefront aberration (HWA) measurement method for a hyper-NA lithographic projection lens based on a binary target with eight directions and rotated regression matrix is proposed. A linear model between the aerial image intensity distribution of the hyper-NA lithographic projection lens and HWAs is built by principal component analysis and regression matrix rotation. Compared to the conventional method using a binary target with six directions, the proposed method improves the efficiency of pupil sampling, increases the modeling speed, extends the measuring range of the wavefront aberrations, and detects the HWAs of the hyper-NA lithographic projection lens accurately. The lithographic simulator PROLITH is used to validate the accuracies of the HWA measurement and analyze the impact of the illumination types of source on the accuracy of the HWA measurement, as well as the polarization rotation of illumination, the sample interval of the aerial images, and the manufacturing error of the test target. The results show that the proposed method retrieves 60 terms of Zernike coefficients ( Z 5 – Z 64 ) with measurement accuracy greater than 1.03 × 10−3 λ .

Comparison of ocular wavefront aberrations in subluxated lenses before and after lens extraction with intraocular lens implantation

To compare the change in ocular higher-order wavefront aberrations (HOAs), visual acuity, and modulation transfer function (MTF) after lens extraction with intraocular lens (IOL) implantation in patients with subluxated lenses. Iladevi Cataract & IOL Research Centre, Ahmedabad, India. Prospective case series. Eyes with subluxated lenses having lens extraction with IOL implantation were included. Capsular bag fixation with in-the-bag IOL implantation or sutured or sutureless scleral fixation of the IOL was performed. Aberrometry was performed preoperatively and 6months postoperatively. The following were compared: root-mean-square (RMS) value for total ocular HOAs, coma aberration, spherical aberration, MTF, and corrected distance visual acuity (CDVA). Of the 39 eyes with subluxated lenses, 26 eyes had Cionni ring fixation, 9 had sutured scleral fixation, and 4 had intrascleral fixation of the IOL. The mean preoperative and postoperative values, respectively, were as follows: RMS HOAs, 10.5μm±9.5 (SD) and 4.73±4.6μm(P<.001); coma aberration, 2.46±2.4μm and 0.11±0.1μm(P=.03); and spherical aberration, 0.37±0.9μm and 0.02±0.06μm(P=.02). The MTF improved significantly in all eyes (mean 0.05±0.02 preoperatively and 0.32±0.16 postoperatively) (P=.005). The CDVA was statistically significant improved 6months postoperatively. Lens extraction with IOL fixation in eyes with subluxated lenses significantly reduced ocular HOAs and improved the MTF.

Corneal functional optical zone under monocular and binocular assessment

BackgroundIn this retrospective randomized case series, we compared bilateral symmetry between OD and OS eyes, intercorneal differences and Functional Optical Zone (FOZ) of the corneal aberrations.MethodsSixty-seven normal subjects (with no ocular pathology) who never had any ocular surgery were bilaterally evaluated at Augenzentrum Recklinghausen (Germany). In all cases, standard examinations and corneal wavefront topography (OPTIKON Scout) were performed. The OD/OS bilateral symmetry was evaluated for corneal wavefront aberrations, and FOZ-values were evaluated from the Root-Mean-Square (RMS) of High-Order Wavefront-Aberration (HOWAb). Moreover, correlations of FOZ, spherical equivalent (SE), astigmatism power, and cardinal and oblique astigmatism for binocular vs. monocular, and binocular vs. intercorneal differences were analyzed.ResultsMean FOZ was 6.56 ± 1.13 mm monocularly, 6.97 ± 1.34 mm binocularly, and 7.64 ± 1.30 mm intercorneal difference, with all strongly positively correlated, showing that the diameter of glare-free vision is larger in binocular than monocular conditions. Mean SE was 0.78 ± 1.30 D, and the mean astigmatism power (magnitude) was 0.46 ± 0.52 D binocularly. The corresponding monocular values for these metrics were 0.78 ± 1.30 D and 0.53 ± 0.53 D respectively. SE, astigmatism magnitude, cardinal astigmatism component, and FOZ showed a strong correlation and even symmetry; and oblique astigmatism component showed odd symmetry indicating Enantiomorphism between the left and right eye.ConclusionsThese results confirm OD-vs.-OS bilateral symmetry (which influences binocular summation) of HOWAb, FOZ, defocus, astigmatism power, and cardinal and oblique astigmatism. Binocular Functional Optical Zone calculated from corneal wavefront aberrations can be used to optimize refractive surgery design.

Wave front aberrations and patient satisfaction of aspheric intraocular lenses

Aim The aim was to study postoperative wave front higher order aberrations of eyes implanted with aspheric intraocular lens (IOL) in comparison with those with standard spherical IOL and to assess the subjective satisfaction in relation to both IOL designs. Patients and methods The study included 40 patients with bilateral cataract. Patients were enrolled in a prospective comparative case series from December 2013 till January 2015. All patients underwent a complete preoperative assessment. Phacoemulsification was done for all patients in both eyes. Aspheric IOL (Acrysof IQ SN60WF) was implanted in the right eye and standard spherical IOL (AcrySof SA60AT) in the left eye. Wave front examination was done at 3 months postoperatively to measure the higher order aberrations. A questionnaire was used to record the patients’ satisfaction regarding the two IOL designs. Results There were no significant differences between the two IOLs regarding the postoperative visual acuity or the mean refractive spherical equivalent. Spherical aberrations were significantly lower in the aspheric IOL group, with only 35% of the patients reported that it was the best eye. There were no significant differences in other aberrations. Conclusion Aspheric IOLs and standard IOLs have the same visual outcome regarding visual acuity. However, aspheric IOLs induced significantly less spherical aberrations. Aspheric IOL gave better qualitative visual functions in some patients especially during night.