Aberrations Of Eye Research Articles

Long eye relief fundus camera and fixation target with partial correction of ocular longitudinal chromatic aberration.

A combined 32° full field of view refractive fundus camera and fixation target with a -20 to +10 diopter sphere correction range is described and demonstrated. The optical setup partially corrects the average longitudinal chromatic aberration and spherical aberration of the human eye, while providing a long eye relief to allow integration with reflective adaptive optics ophthalmoscopes, as a viewfinder. The fundus camera operates with 940 nm light, using a maximum 2.9 mm diameter imaging pupil at the eye. The fixation target uses a light projector capable of delivering red, green and/or blue spatially and temporally modulated stimuli to the retina. The design and performance of each sub-system are discussed, and retinal imaging at various wavelengths is demonstrated.

Role of the smallish gene during Drosophila eye development

Smallish (Smash), the Drosophila homologue of human LIM domain only 7 (LMO7), is a key regulator of Drosophila embryogenesis associated with planner cell polarity and actomyosin contractility at the zonula adherence. Although smash mRNA is expressed in several tissues during Drosophila development, only Smash function at the adherence junction in the embryonic epithelial cells has been reported. We herein demonstrated that the knockdown of smash in eye imaginal discs induced morphological aberrations in adult compound eyes that were associated with increased apoptosis. Furthermore, immunohistochemical analyses revealed that Smash localized to the nucleus in several tissues, including eye imaginal discs. The knockdown of smash in eye imaginal discs down-regulated the expression of the ote and bocks genes as well as the Drosophila homologue of the emerin gene, which is a target of LMO7. Collectively, these results indicate that Smash functions in proper Drosophila eye development mediated by the regulation of ote and bocks gene expression.

Creating correct blur and its effect on accommodation.

Blur occurs naturally when the eye is focused at one distance and an object is presented at another distance. Computer-graphics engineers and vision scientists often wish to create display images that reproduce such depth-dependent blur, but their methods are incorrect for that purpose. They take into account the scene geometry, pupil size, and focal distances, but do not properly take into account the optical aberrations of the human eye. We developed a method that, by incorporating the viewer's optics, yields displayed images that produce retinal images close to the ones that occur in natural viewing. We concentrated on the effects of defocus, chromatic aberration, astigmatism, and spherical aberration and evaluated their effectiveness by conducting experiments in which we attempted to drive the eye's focusing response (accommodation) through the rendering of these aberrations. We found that accommodation is not driven at all by conventional rendering methods, but that it is driven surprisingly quickly and accurately by our method with defocus and chromatic aberration incorporated. We found some effect of astigmatism but none of spherical aberration. We discuss how the rendering approach can be used in vision science experiments and in the development of ophthalmic/optometric devices and augmented- and virtual-reality displays.

Neural mechanisms of long-term adaptation to the eye's habitual aberration

Neural mechanisms of long-term adaptation to the eye's habitual aberration

Analytical method for the transformation of Zernike polynomial coefficients for scaled, rotated, and translated pupils.

Zernike polynomials provide an excellent metric basis for characterizing the wavefront aberrations of human eyes and optical systems. Since the Zernike expansion is dependent on the size, position, and orientation of the pupil in which the function is defined, it is often necessary to transform the Zernike coefficients between different pupils. An analytic method of transforming the Zernike coefficients for scaled, rotated, and translated pupils is proposed in this paper. The normalized coordinate transformation functions between the polar coordinates of the transformed pupil and the Cartesian coordinates of the original pupil are given. Based on the Cartesian and polar representations of Zernike polynomials, the coefficients' transformation matrix can be derived directly and conveniently. The first 36 terms of standard Zernike polynomials are used to validate the proposed method. For different types of transformation, transformation rules of individual Zernike terms are systematically analyzed, revealing how individual terms of the original pupil transform into terms of the transformed pupil. Numerical examples are presented to demonstrate the validity of the proposed method. Further application of the proposed method to the alignment of pupil-decentered off-axis optical systems is discussed.

Flexible retinal image formation by holographic Maxwellian-view display.

The Maxwellian-view display can provide visual information to people with low vision because retinal images can be formed independently of the refractive power of an eye by using rays converging on its pupil. This study presents the holographic Maxwellian-view display, which generates a wavefront converging on the pupil and forming images on the retina. The beam convergent point can be moved electrically in accordance with the pupil movement, and the beam width in the pupil can be changed electrically to control the depth of field of the eye. A compact optical system configuration for the holographic Maxwellian-view display is also proposed. The prototype system was constructed and experimentally tested. Because this holographic technique allows the phase modulation in the pupil, eye aberrations can be corrected; thus, retinal images can be formed for eyes with astigmatism.

Distribution of posterior corneal astigmatism and aberration before cataract surgery in Chinese patients

To study the prevalence of posterior corneal astigmatism (PCA) and aberration in Chinese eyes before cataract surgery. A cross-sectional study was conducted in Eye and ENT Hospital of Fudan University, Shanghai. In all, we enrolled 1976 eligible eyes of 1976 cataract patients. The astigmatism and aberrations of anterior and posterior cornea were measured by the rotating Scheimpflug System (Pentacam HR, Oculus). Cataract was diagnosed using slit-lamp examination. The mean age of patients was 61.82 ± 13.67 years old. Mean PCA was 0.28 ± 0.16 (range 0-1.0) D and 87.04% eyes had PCA values <0.5 D. WTR astigmatism predominated the anterior cornea astigmatism (43.1%), while ATR astigmatism predominated posterior (85.4%) and total corneal astigmatism (47.2%). We found a shift tendency of WTR to ATR with aging in anterior corneal astigmatism, while PCA remains ATR. A positive correlation between the magnitude of anterior and posterior corneal astigmatism (r2 = 0.089, P < 0.001) was found, especially in WTR anterior cornea astigmatism eyes (r2 = 0.298, P < 0.001). Compared with total corneal astigmatism, anterior corneal measurements overestimated WTR astigmatism by a mean of 0.24 ± 0.13 (D), and underestimated ATR astigmatism and oblique astigmatism in most eyes. Furthermore, anterior corneal aberrations measurements overestimated the total corneal aberration in most eyes. About 12.96% of eyes had PCA ≥0.5 D. The posterior surface remained ATR astigmatism in most cases with aging. Neglecting the posterior cornea would result in overestimation in WTR anterior corneal eyes and underestimation in ATR and oblique anterior corneal eyes. Also, the posterior corneal aberration was also essential in clinics.

Spherical aberration of camera-like eyes

The longitudinal and transverse spherical aberrations are estimated for the reduced camera-like eyes of gastropod mollusks and humans, and by comparing the latter with the diffraction limit, its effect on the resolving power in the center of the retina is analyzed. It is shown that these two types of aberration remain unchanged in the mollusk because of the constant diameter of the pupil and it increases in the human eye with an increase in the pupil diameter. Furthermore, the longitudinal aberration is always greater than the transverse value, and the difference between them decreases with increasing pupil diameter. The magnitude of the spherical aberration is comparable to the value of the diffraction limit of resolution of the mollusk’s eye and begins to exceed the value of the diffraction limit of the resolving power of the human eye with a pupil diameter of more than 4.6 mm.

Changes of ocular wave aberration in keratoconus eyes wearing mini-scleral contact lens

Purpose: to determine changes in ocular wave aberration (WA) when keratoconus eyes are fitted with mini scleral contact lens (msCL).

How do different visual rehabilitation methods affect aberrations in keratoconus?

Purpose: To evaluate and compare the aberrations of keratoconic eyes with different visual rehabilitations (glasses, RGPs and keratoplasty)to healthy eyes.

In vivo blind-deconvolution photoacoustic ophthalmoscopy with total variation regularization.

Photoacoustic ophthalmoscopy (PAOM) is capable of noninvasively imaging anatomic and functional information of the retina in living rodents. However, the strong ocular aberration in rodent eyes and limited ultrasonic detection sensitivity affect PAOM's spatial resolution and signal-to-noise ratio (SNR) in in vivo eyes. In this work, we report a computational approach to combine blind deconvolution (BD) algorithm with a regularizing constraint based on total variation (BDTV) for PAOM imaging restoration. We tested the algorithm in retinal and choroidal microvascular images in albino rat eyes. The algorithm improved PAOM's lateral resolution by around 2-fold. Moreover, it enabled the improvement in imaging SNR for both major vessels and capillaries, and realized the well-preserved blood vessels' edges simultaneously, which surpasses conventional Richardson-Lucy BD algorithm. The reported results indicate that the BDTV algorithm potentially facilitate PAOM in extracting retinal pathophysiological information by enhancing in vivo imaging quality without physically modifying PAOM's optical configuration.

Evaluation of Optical Quality: Ocular Scattering and Aberrations in Eyes Implanted with Diffractive Multifocal or Monofocal Intraocular Lenses

ABSTRACTPurpose: To compare objective optical quality, ocular scattering and aberrations of eyes implanted with an aspheric monofocal intraocular lens (IOL) or an aspheric apodized diffractive multifocal IOL three months after surgery.Methods: Prospective consecutive nonrandomized comparative cohort study. A total of 80 eyes from 57 cataract patients were bilaterally or unilaterally implanted with monofocal (AcrySof IQ SN60WF) or multifocal (AcrySof IQ ReSTOR SN6AD1) IOLs. Respectively, 40 eyes of 27 patients were implanted with monofocal IOLs, and 40 eyes of 30 patients were implanted with multifocal IOLs. Ocular high-order aberration (HOA) values were obtained using Hartmann–Shack aberrometer; objective scatter index (OSI), modulation transfer function (MTF) cutoff, Strehl ratio (SR), and contrast visual acuity OV at 100%, 20%, and 9% were measured using Objective Quality Analysis System II (OQAS II).Results: Ocular aberrations performed similar in both groups (p > 0.05). However, significantly higher values of OSI and lower values of MTF cutoff, SR and OV were found in the SN6AD1 group (p < 0.05).Conclusions: Both ocular scattering and wave-front aberrations play essential role in retinal image quality, which may be overestimated when only aberrations were taken into account. Combining the effect of ocular scattering with HOA will result in a more accurate assessment of the visual and optical quality.

Ultrahigh resolution retinal imaging by visible light OCT with longitudinal achromatization.

Chromatic aberrations are an important design consideration in high resolution, high bandwidth, refractive imaging systems that use visible light. Here, we present a fiber-based spectral/Fourier domain, visible light OCT ophthalmoscope corrected for the average longitudinal chromatic aberration (LCA) of the human eye. Analysis of complex speckles from in vivo retinal images showed that achromatization resulted in a speckle autocorrelation function that was ~20% narrower in the axial direction, but unchanged in the transverse direction. In images from the improved, achromatized system, the separation between Bruch's membrane (BM), the retinal pigment epithelium (RPE), and the outer segment tips clearly emerged across the entire 6.5 mm field-of-view, enabling segmentation and morphometry of BM and the RPE in a human subject. Finally, cross-sectional images depicted distinct inner retinal layers with high resolution. Thus, with chromatic aberration compensation, visible light OCT can achieve volume resolutions and retinal image quality that matches or exceeds ultrahigh resolution near-infrared OCT systems with no monochromatic aberration compensation.

Controlled elevation of intraocular pressure and its impact on ocular aberrations in healthy eyes

Controlled elevation of intraocular pressure and its impact on ocular aberrations in healthy eyes

Peripheral Monochromatic Aberrations in Young Adult Caucasian and East Asian Eyes.

Myopia prevalence rates differ between racial groups. If the growth of the eye is sensitive to differences in optical input, the difference in spherical aberration between East Asian and Caucasian eyes found in this study may be important in understanding myopia development. The aim of this study was to determine differences in peripheral wavefront aberrations between two racial groups. Wavefront aberrations were measured using a COAS-HD aberrometer across the 42 × 32° central visual field on 37 right eyes of young adults (18 Caucasians, 19 East Asians; mean age 21.5 ± 2.4 years). The mean spherical equivalent refraction was -1.94 ± 1.63 diopters (D) with a range of -5.87 to +0.16 D. Effect of race and visual field position on refractions, individual Zernike aberration coefficients up to the fourth order, higher-order root-mean-square aberration, and total root-mean-square aberration were assessed by repeated-measures analysis of covariance. Caucasians and East Asians had similar relative peripheral myopia across the visual field. All higher-order aberration coefficients were affected by visual field position. Race had no significant effect on any higher-order Zernike coefficient, but the difference in mean vertical coma coefficient (Equation is included in full-text article.)across the visual field (i.e., average of 38 field locations) approached significance, being less positive in Caucasians than in East Asians (P = .08). When correction was made for the Caucasian group being slightly less myopic than the East Asian group, spherical aberration coefficient (Equation is included in full-text article.)was less positive in Caucasians than in East Asians by 0.04 μm (P = .001). The rates of change of coma coefficients across the field were not affected by race. Caucasians and East Asians had similar relative peripheral myopia, but with less positive spherical aberration coefficient in Caucasians than in East Asians. It remains to be determined whether aberrations have a role in the difference of myopia prevalence rates in different countries.

Higher-Order Aberrations After Cyclopentolate, Tropicamide, and Artificial Tear Drops Application in Normal Eyes.

To determine the effect of cyclopentolate, tropicamide, and artificial tear drops on higher-order aberrations (HOAs) in normal eyes with OPD-Scan III (Nidek Inc., Tokyo, Japan). In this study, 189 eyes of individuals aged 20 to 35 years were selected as samples. Inclusion criteria were a corrected visual acuity of 20/20 or better, a minimum size of about 5 mm for the pupil in the dark, hyperopia and myopia less than 5 D, and astigmatism less than 2 D. Moreover, participants with pathological eye problems, a history of intraocular surgery, and ocular diseases affecting the accommodation, pupil size, and corneal surface were excluded. Higher-order aberrations of the participants were assessed by the OPD-Scan III before and after cyclopentolate (Colircuss), tropicamide (Mydrax 0.5%), and artificial tears (Tearlose) drop instillation. After instilling cyclopentolate drops, the mean of the total root mean square (RMS) increased from 4.580 to 6.335 D, total spherical aberration increased from 0.155 to 0.381 D, and total coma increased from 0.195 to 0.369 D; the increases were significant for total RMS and total spherical aberration, but a significant relationship was not seen with total coma. After tropicamide, the mean aberrations of total RMS increased from 4.301 to 4.568 D, total spherical aberration increased from 0.146 to 0.160 D, and total coma increased from 0.213 to 0.230 D; the increase was only significant for total coma. On the other hand, after artificial tears, the average of all aberrations decreased in a nonsignificant manner. Most changes of mean aberrations were related to cyclopentolate drops. Tropicamide and artificial tears had the second and third rank according to their effect on mean errors. As a result, it seems that ocular accommodation is the most important impact on HOA than pupil size. However, the pupil size is the second factor for HOAs.

Cornea and anterior eye assessment with placido-disc keratoscopy, slit scanning evaluation topography and scheimpflug imaging tomography.

Current corneal assessment technologies make the process of corneal evaluation extremely fast and simple and several devices and technologies allow to explore and to manage patients. The purpose of this special issue is to present and also to update in the evaluation of cornea and ocular surface and this second part, reviews a description of the corneal topography and tomography techniques, providing updated information of the clinical recommendations of these techniques in eye care practice. Placido-based topographers started an exciting anterior corneal surface analysis that allows the development of current corneal tomographers that provide a full three-dimensional reconstruction of the cornea including elevation, curvature, and pachymetry data of anterior and posterior corneal surfaces. Although, there is not an accepted reference standard technology for corneal topography description and it is not possible to determine which device produces the most accurate topographic measurements, placido-based topographers are a valuable technology to be used in primary eye care and corneal tomograhers expanding the possibilities to explore cornea and anterior eye facilitating diagnosis and follow-up in several situations, raising patient follow-up, and improving the knowledge regarding to the corneal anatomy. Main disadvantages of placido-based topographers include the absence of information about the posterior corneal surface and limited corneal surface coverage without data from the para-central and/or peripheral corneal surface. However, corneal tomographers show repeatable anterior and posterior corneal surfaces measurements, providing full corneal thickness data improving cornea, and anterior surface assessment. However, differences between devices suggest that they are not interchangeable in clinical practice.

A New Decomposition Basis for The Classification of Aberrations of The Human Eye

The optical defects of the human eye are analyzed and classified by studying the corre-sponding ocular wavefront. After presenting the orthogonal basis, called the Zernike basis, which is currently used for the wavefront analysis, a new mathematical decomposition basis is built. In this new basis, the phase errors due to the low degree aberrations terms are totally separated from the high order terms, in order to improve the relevance of the clinical interpretation through a better appreciation of the low vs high aberration wavefront components. Various clinical examples (myopia, keratoconus) clearly show the interest of this new basis compared to a diagnosis based on the Zernike decomposition.

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.

The effect of spherical aberration on visual performance and refractive state for stimuli and tasks typical of night viewing

PurposeThe aim of this work was to examine the impact of Seidel spherical aberration (SA) on optimum refractive state for detecting and discriminating small bright lights on a dark background. MethodsAn adaptive-optics system was used to correct ocular aberrations of cyclopleged eyes and then systematically introduce five levels of Seidel SA for a 7-mm diameter pupil: 0,±0.18, and±0.36diopters (D)mm−2. For each level of SA, subjects were required to detect one or resolve two points of light (0.54 arc min diameter) on a dark background. Refractive error was measured by adjusting stimulus vergence to minimize detection and resolution thresholds. Two other novel focusing tasks for single points of light required maximizing the perceived intensity of a bright point's core and minimizing its overall perceived size (i.e. minimize starburst artifacts). Except for the detection task, luminance of the point of light was 1000cdm−2 on a black background lower than 0.5cdm−2. ResultsPositive SA introduced myopic shifts relative to the best subjective focus for dark letters on a bright background when there was no SA, whereas negative SA introduced hyperopic shifts in optimal focus. The changes in optimal focus were −1.7, −2.4, −2.0, and −9.2D of focus per Dmm−2 of SA for the detection task, resolution task, and maximization of core's intensity and minimization of size, respectively. ConclusionOcular SA can be a significant contributor to changes in refractive state when viewing high-contrast point sources typically encountered in nighttime environments.