Wavefront Aberrations In Eyes Research Articles

Comparison of wavefront aberrations in eyes with multifocal and monofocal iols before and after Nd:YAG laser capsulotomy for posterior capsule opacification.

The aim of this study was to compare wavefront aberrations before and after Nd:YAG capsulotomy in multifocal intraocular lens (MfIOL) and monofocal (MoIOL) pseudophakic eyes with posterior capsule opacification (PCO). Wavefront aberrations were measured using a ARK-10000 topographer before and after Nd:YAG capsulotomy in eyes that underwent MfIOL or MoIOL implantation and developed PCO. Total and higher-order aberrations (HOAs) values were evaluated as root mean square (RMS). The study included 64 eyes with MfIOLs (64 patients) and 72 with MoIOLs (72 patients) that developed PCO. Total RMS values before and 1month after Nd:YAG capsulotomy were 0.863 ± 0.27 and 0.504 ± 0.24 in the MFIOL group and 0.862 ± 0.31 and 0.466 ± 0.26 in the MoIOL group, respectively. Total RMS values did not differ significantly between the groups before (p = 0.914) or 1month after Nd:YAG laser capsulotomy (p = 0.357), but decreased significantly after Nd:YAG capsulotomy compared to baseline in both the MfIOL (p = 0.027) and MoIOL (p = 0.012) groups. HOA values before and 1month after Nd:YAG capsulotomy were 0.546 ± 0.23 and 0.364 ± 0.19 in the MfIOL group and 0.500 ± 0.21 and 0.346 ± 0.18 in the MoIOL group, respectively. HOA values did not differ significantly before (p = 0.828) or after Nd:YAG capsulotomy (p = 0.111), while both groups showed significant reduction in HOAs after Nd:YAG capsulotomy (MfIOL: p = 0.021, MoIOL: p = 0.027). Nd:YAG capsulotomy reduces total and HOAs to the same extent in eyes with both MfIOLs and MoIOLs, with no significant impact of the IOL design.

Image system analysis of human eye wave-front aberration on the basis of HSS

Hartmann–Shack sensor (HSS) has been used in objective measurement of human eye wave-front aberration, but the research on the effects of sampling point size on the accuracy of the result has not been reported. In this paper, point spread function (PSF) of the whole system mathematical model was obtained via measuring the optical imaging system structure of human eye wave-front aberration measurement. The impact of Airy spot size on the accuracy of system was analyzed. Statistics study show that the geometry of Airy spot size of the ideal light source sent from eye retina formed on the surface of HSS is far smaller than the size of the HSS sample point image used in the experiment. Therefore, the effect of Airy spot on the precision of the system can be ignored. This study theoretically and experimentally justifies the reliability and accuracy of human eye wave-front aberration measurement based on HSS.

Evaluation of the True Wavefront Aberrations in Eyes Implanted With a Rotationally Asymmetric Multifocal Intraocular Lens.

Standard evaluation of aberrations from wavefront slope measurements in patients implanted with a rotationally asymmetric multifocal intraocular lens (IOL), the Lentis Mplus (Oculentis GmbH, Berlin, Germany), results in large magnitude primary vertical coma, which is attributed to the intrinsic IOL design. The new proposed method analyzes aberrometry data, allowing disentangling the IOL power pupillary distribution from the true higher order aberrations of the eye. The new method of wavefront reconstruction uses retinal spots obtained at both the near and far foci. The method was tested using ray tracing optical simulations in a computer eye model virtually implanted with the Lentis Mplus IOL, with a generic cornea or with anterior segment geometry obtained from custom quantitative spectral-domain optical coherence tomography in a real patient. The method was applied to laser ray tracing aberrometry data at near and far fixation obtained in a patient implanted with the Lentis Mplus IOL. Higher order aberrations evaluated from simulated and real retinal spot diagrams following the new reconstruction approach matched the nominal aberrations (approximately 98%). Previously reported primary vertical coma in patients implanted with this IOL lost significance with the application of the proposed reconstruction. Custom analysis of ray tracing-based retinal spot diagrams allowed decoupling of the true higher order aberrations of the patient's eye from the power pupillary distribution of a rotationally asymmetric multifocal IOL, therefore providing the appropriate phase map to accurately evaluate through-focus optical quality. [J Refract Surg. 2017;33(4):257-265.].

From corneal shape to ocular wavefront in eyes with aspheric IOLs: the feasibility of IOL customisation.

To determine if it is possible to predict the ocular wavefront aberrations of eyes with an aspheric IOL from the corneal shape and other readily available eye characteristics. A reliable prediction is a prerequisite for future IOL customisation. Sixty pseudophakic eyes with aspheric IOLs of 60 patients were included. The corneal shape and the ocular wavefront aberrations were measured postoperatively with a Scheimpflug camera and an aberrometer, respectively. The elevation data of the anterior corneal surface were fitted by Zernike polynomials. Linear regression models for the Zernike coefficients describing the ocular wavefront aberrations up till the fourth order were determined, with as independent variables the Zernike coefficients describing the corneal shape, the eye (right/left), IOL power, and axial length. Linear regression equations with an explained variance (adjusted R-square) above 0.50 were found for five Zernike aberration terms: defocus (z(2,0); adjusted R-square 0.90), the astigmatism terms (0.81 for oblique astigmatism [z(2,-2)] and 0.88 for regular astigmatism [z(2,2)]), vertical coma (z(3,-1); 0.52), and spherical aberration (z(4,0); 0.71). The defocus, astigmatism, vertical coma, and spherical aberration terms of the ocular wavefront are strongly associated with the corneal shape in pseudophakic eyes and may thus be predicted from the corneal shape and other eye characteristics.

High Resolution Retinal Imaging Based on Ocular Aberration Measurement and Compensation

Ocular retinal imaging is a major diagnostic modality for retinal disease, and can play a critical role for diagnosing systemic diseases such as diabetes and eye-specific diseases such as macular degeneration and diabetic retinopathy, the leading causes of blindness. In order to get high-resolution retinal imaging and develop the low-cost and compact retinal imaging system, we employ micro adaptive optics, which is consisted of wavefront sensor, wavefront corrector and control system. In this paper, the theory, design and testing of the ocular retinal microscopy is detailed, with an emphasis on the eye wavefront aberration describing, aberration detecting method with Hartmann-Shack wavefront sensing and close-loop aberration compensating by micromachined membrane deformable mirrors(MMDM).The ocular retinal microscopy experimental setup is built, the retinal cell imaging had been snapped. It is showed in this work that the ocular retinal microscopy based on adaptive optics system can enable diffraction-limited imaging of micro-scale features of the retina, through real-time compensation of aberrations introduced by the eye.

High-resolution retinal imaging with micro adaptive optics system

Based on the dynamic characteristics of human eye aberration, a microadaptive optics retina imaging system set is established for real-time wavefront measurement and correction. This paper analyzes the working principles of a 127-unit Hartmann-Shack wavefront sensor and a 37-channel micromachine membrane deformable mirror adopted in the system. The proposed system achieves wavefront reconstruction through the adaptive centroid detection method and the mode reconstruction algorithm of Zernike polynomials, so that human eye aberration can be measured accurately. Meanwhile, according to the adaptive optics aberration correction control model, a closed-loop iterative aberration correction algorithm based on Smith control is presented to realize efficient and real-time correction of human eye aberration with different characteristics, and characteristics of the time domain of the system are also optimized. According to the experiment results tested on a USAF 1951 standard resolution target and a living human retina (subject ZHY), the resolution of the system can reach 3.6 LP/mm, and the human eye wavefront aberration of 0.728λ (λ=785 nm) can be corrected to 0.081λ in root mean square (RMS) so as to achieve the diffraction limit (Strehl ratio is 0.866), then high-resolution retina images are obtained.

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.

Wave aberration of human eyes and new descriptors of image optical quality and visual performance

The expansion of wavefront-sensing techniques redefined the meaning of refractive error in clinical ophthalmology. Clinical aberrometers provide detailed measurements of the eye's wavefront aberration. The distribution and contribution of each higher-order aberration to the overall wavefront aberration in the individual eye can now be accurately determined and predicted. Using corneal or ocular wavefront sensors, studies have measured the interindividual and age-related changes in the wavefront aberration in the normal population with the goal of optimizing refractive surgery outcomes for the individual. New objective optical-quality metrics would lead to better use and interpretation of newly available information on aberrations in the eye. However, the first metrics introduced, based on sets of Zernike polynomials, is not completely suitable to depict visual quality because they do not directly relate to the quality of the retinal image. Thus, several approaches to describe the real, complex optical performance of human eyes have been implemented. These include objective metrics that quantify the quality of the optical wavefront in the plane of the pupil (ie, pupil-plane metrics) and others that quantify the quality of the retinal image (ie, image-plane metrics). These metrics are derived by wavefront aberration information from the individual eye. This paper reviews the more recent knowledge of the wavefront aberration in human eyes and discusses the image-quality and optical-quality metrics and predictors that are now routinely calculated by wavefront-sensor software to describe the optical and image quality in the individual eye.

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.

The Role of Cardiopulmonary Signals in the Dynamics of the Eye’s Wavefront Aberrations

The role of cardiopulmonary signals in the dynamics of wavefront aberrations in the eye has been examined. Synchronous measurement of the eye's wavefront aberrations, cardiac function, blood pulse, and respiration signals were taken for a group of young, healthy subjects. Two focusing stimuli, three breathing patterns, as well as natural and cycloplegic eye conditions were examined. A set of tools, including time-frequency coherence and its metrics, has been proposed to acquire a detailed picture of the interactions of the cardiopulmonary system with the eye's wavefront aberrations. The results showed that the coherence of the blood pulse and its harmonics with the eye's aberrations was, on average, weak ( 0.4+/-0.15), while the coherence of the respiration signal with eye's aberrations was, on average, moderate ( 0.53+/-0.14). It was also revealed that there were significant intervals during which high coherence occurred. On average, the coherence was high ( > 0.75) during 16% of the recorded time, for the blood pulse, and 34% of the time for the respiration signal. A statistically significant decrease in average coherence was noted for the eye's aberrations with respiration in the case of fast controlled breathing (0.5 Hz). The coherence between the blood pulse and the defocus was significantly larger for the far target than for the near target condition. After cycloplegia, the coherence of defocus with the blood pulse significantly decreased, while this was not the case for the other aberrations. There was also a noticeable, but not statistically significant, increase in the coherence of the comatic term and respiration in that case. By using nonstationary measures of signal coherence, a more detailed picture of interactions between the cardiopulmonary signals and eye's wavefront aberrations has emerged.

Mesopic Contrast Sensitivity and Ocular Higher-Order Aberrations in Eyes With Conventional Spherical Intraocular Lenses

To investigate relationship between mesopic contrast sensitivity (CS) function and ocular higher-order aberrations in eyes implanted with conventional spherical intraocular lenses (IOL). Prospective, nonrandomized case series. Sixty-eight eyes of 48 patients who attained best spectacle-corrected visual acuity (BSCVA) of 20/20 or better after phacoemulsification and spherical IOL implantation were included in the study. At 2 months postoperatively, mesopic CS was measured with the Mesotest II (Oculus; Wetsler, Germany), and ocular higher-order aberrations for a 4-mm pupil were measured with the Hartmann-Shack aberrometer. CS and letter CS under photopic conditions were recorded with the CSV-1000 charts (Vector Vision Co, Greenville, Ohio, USA). There was significant correlation between mesopic CS and ocular fourth-order root mean square (RMS) of wavefront aberration (Spearman r(s) = -0.293; P = .017), but no correlation was found between mesopic CS and ocular third-order RMS (r(s) = 0.196; P = .189). Ocular third- and fourth-order RMS did not correlate with other parameters, including BSCVA, and CS and letter CS under photopic conditions. Mesopic CS is significantly associated with ocular fourth-order RMS of wavefront aberrations in eyes implanted with conventional spherical IOLs.

Wavefront aberrations in eyes with decentered ablations

To compare the refractive and functional outcomes and wavefront profiles in eyes with decentered ablations and eyes with well-centered ablations. Medical Research Foundation, Chennai, Tamil Nadu, India. This retrospective analysis comprised eyes with topographically diagnosed decentered ablations after laser in situ keratomileusis (LASIK). Refraction, contrast sensitivity, and ocular wavefront aberrations were measured preoperatively and 1 month postoperatively. The induced aberrations in these eyes were compared with those in eyes with well-centered ablations. Forty-six eyes (38 patients) had decentered ablations and 60 eyes (32 patients), well-centered ablations. The mean decentration in the study group was 0.86 mm +/- 0.29 (SD) (range 0.35 to 1.61 mm). There was no significant correlation between decentration and attempted refractive correction. There was, however, a statistically significant (P<.05) linear correlation between the distance of decentration and the magnitude of induced tilt (r = -0.31), coma (r = -0.41), and secondary astigmatism (r = 0.36). The induced changes in tilt, oblique astigmatism, vertical coma, and spherical aberration were statistically significantly higher in eyes with decentered ablations than in eyes with well-centered ablations. A statistically significantly higher percentage of eyes (87%) with well-centered ablations than eyes with decentered ablations (70%) had a postoperative uncorrected visual acuity (UCVA) of 20/20 or better. There was no significant difference in contrast sensitivity between groups. Eyes with decentered ablations had a significantly higher magnitude of induced aberrations and lower UCVA than eyes with well-centered ablations.

Comparison of contrast sensitivity, depth of field and ocular wavefront aberrations in eyes with an IOL with zero versus positive spherical aberration

To compare the clinical performance of the zero spherical aberration (SA) SofPort LI61AO (AO, Bausch & Lomb) intraocular lens (IOL) to the AcrySof SA60AT (AT, Alcon), which has positive spherical aberration. Patients underwent uneventful phacoemulsification with implantation of either an aspheric (AO, n = 19) or spherical (AT, n = 20) IOL. Postoperatively, a 5 mm artificial pupil was positioned in trial frames with the cycloplegic refraction during monocular, mesopic contrast sensitivity (CSF) and low-contrast visual acuity (LCVA) testing with glare. Ocular and corneal wavefront error was determined at 5 mm diameters. Mean CSF scores were better at all frequencies tested for the AO than for the AT group, and achieved statistical significance at 1.5 cpd (p = 0.038) and 6 cpd (p = 0.017). With glare, AO eyes read 30.9 +/- 5.0 low-contrast letters versus 25.2 +/- 6.8 for AT eyes (p = 0.005) (mean DeltaLogMAR = -0.10), while high-contrast acuity and refraction were similar. Eyes implanted with the SA60AT had 43% greater positive spherical aberration at a 5 mm wavefront diameter, with no significant difference in corneal SA between groups. A through-focus analysis demonstrated a similar depth of field, yet a comparatively higher visual Strehl ratio for the aspheric IOL at emmetropia (p = 0.038). Eyes with the SofPort Advance Optics neutral aberration IOL demonstrated less spherical aberration and better low-contrast acuity compared to eyes with a spherical IOL, without sacrificing tolerance to defocus. The aspheric IOL showed superior optical and clinical performance, which is most likely due to its surface design.

Higher-Order Wavefront Aberrations for Populations of Young Emmetropes and Myopes

Purpose To test the hypothesis that human eyes have a central tendency to be free of higher-order aberrations by analyzing wavefront aberrations for two young populations of respectively emmetropic and myopic subjects. Methods Both right and left eyes of 75 emmetropes and 196 myopes were measured for corneal wavefront aberration using a Humphrey corneal topographer and for the whole eye wavefront aberration using a WASCA wavefront sensor without pupil dilation. 35 Zernike aberration coefficients over a 6.0 mm pupil diameter were derived, and statistics of the higher-order terms (3 rd to 5 th orders) were tested. Results When signed Zernike aberrations of the right and left eyes were averaged together for the emmetropes, three higher-order modes (j=6, 12 and 13) were significantly different from zero in both the cornea and the whole eye ( P<0.0005), and three additional terms (j=14, 15 and 17) were statistically non-zero for the whole eye. As the signs of y-axis asymmetrical terms in the left eye were flipped, three more terms in either the cornea (j=8, 18 and 19) or the whole eye (j=8, 10 and 20) became statistically non-zero. For the myopes, 8 corneal terms and 5 whole-eye terms were statistically non-zero when the two eyes were averaged together. As the signs flipped, the majority of the Zernike aberration terms were statistically different from zero. Conclusions Human eyes have systematical higher order aberrations in population, and factors that cause bilateral symmetry of wavefront aberrations between the right and left eyes made important contribution to the systematical aberrations.

Wavefront analysis of acrylic spherical and aspherical intraocular lenses

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

Effect of Hormone Replacement Therapy in Women on Ocular Refractive Status and Aberrations

To evaluate the effects of hormone replacement therapy (HRT) on refractive status, corneal topography, and aberrations of the eye in postmenopausal women. Thirty-six healthy postmenopausal women (72 eyes) were included in the study. All patients received HRT that consisted of 0.625 mg/day conjugated estrogen and 5 mg/day medroxyprogesterone acetate in a continuous combined regimen. Schirmer II test and tear film break-up time (BUT) were performed on all patients at the time of enrollment and 6 months after initiation of HRT. Refractive status, corneal topography, and wavefront aberrations were evaluated with the NIDEK Optical Path Difference-Scan before and 6 months after HRT was initiated. Mean patient age was 50.8 +/- 2.6 years (range: 47 to 57 years). The mean duration of menopause was 2.7 +/- 0.8 years (range: 1.4 to 3.5 years). The Schirmer II test and tear film BUT measurements were significantly lower after HRT (P < .05). Before HRT, the mean spherical equivalent refraction was -0.19 +/- 1.79 diopters (D) (range: -4.38 to +3.00 D). After HRT, the mean spherical equivalent refraction was -0.22 +/- 1.81 D (range: -4.63 to +/- 2.63 D). No significant differences were noted between refractive status, corneal topography, and wavefront aberrations of eyes of patients before and 6 months after HRT (P > .05). Hormone replacement therapy in postmenopausal women does not significantly affect refractive status, corneal topography, and wavefront aberrations of the eye at 6-month follow-up.

Corneal First Surface Wavefront Aberrations Before and After Pterygium Surgery

To determine the higher order aberrations at the corneal first surface before and after surgery for pterygium. Data were drawn from a longitudinal study of patients undergoing pterygium excision at Royal Victoria Infirmary, Newcastle upon Tyne, England between September 1998 and May 2004. Corneal topography was taken with the TMS-2 Topographic Modeling System (Computed Anatomy Corp) prior to and 6 months after surgery, exported to VOLPro software v7.08 (Sarver & Associates), and wavefront aberrations were derived for a 5.0-mm pupil using a 10th order Zernike polynomial expansion. Pre- to postoperative changes were assessed for significance using analyses of variance, and the relative risk of significant postoperative aberrations by pterygium size was determined. Satisfactory corneal topography was available on 67 eyes (mean age 53.8 +/- 16.7 years [range: 25-86 years]). The root-mean-square (RMS) fit error in preoperative eyes was 0.15 +/- 0.10 microm. Preoperatively, the total higher order RMS wavefront aberration was 0.94 +/- 0.83 microm. All Zernike modes were elevated, with trefoil being the major contributor 0.52 +/- 0.50 microm. Pterygium excision significantly reduced wavefront aberrations across all modes and orders (F(1, 129) = 6.7 to 22.6, P < .01): total higher order RMSpostop 0.45 +/- 0.35 microm. Cases with visually significant postoperative aberrations occurred and were more likely with larger pterygia: relative risk compared to pterygia 1.0 to 1.9 mm was 1.3 for 2.0 to 2.9 mm, 8.5 for 3.0 to 3.9 mm, 13.3 for 4.0 to 4.9 mm, and 10.2 for 5.0 to 5.9 mm. Zernike polynomial fitting well describes wavefront aberrations in eyes with pterygia. Pterygia are associated with wavefront aberrations, especially trefoil, but these were largely eliminated by surgery. Earlier excision of pterygia reduces the likelihood of significant residual aberrations.

A Comparison of Wavefront Aberrations in Eyes Wearing Different Types of Soft Contact Lenses

The purpose of this study is to investigate the optical quality of eyes wearing different types of soft contact lenses (sCLs) using wavefront aberrometry. A psychophysical aberrometer (WFA1000B; BriteEye, SuZhou, China) was used to measure wavefront aberrations for 56 eyes of 28 subjects under four conditions: 1) without contact lenses (non-CL), 2) with lathe-cut contact lenses (lathe-cut CL; Shuliang, Weicon Optics, Shanghai, China), 3) with cast-molded contact lenses (cast-molded CL; Vistavue, J&J Vision Care, U.S.), and 4) with spun-cast contact lenses (spun-cast CL; Lanfenzhiji, Justcome Optics, Beijing, China). The three types of sCLs were made from different materials and lens design. The root mean square (RMS) values of the wavefront aberrations and individual Zernike aberrations were calculated and compared among the CL-wearing conditions. Astigmatism was not significantly changed by any of the three soft contact lenses when compared with the non-CL condition. However, a significant difference in the RMS values of higher-order aberrations was observed between the lens types (F=8.29, p<0.0001). Induced higher-order aberrations were found for both the cast-molded CL and the spun-cast CL conditions. There were significant differences in the aberrations in each of the higher orders between the CL conditions (F=3.77, p=0.011 for third order; F=5.31, p=0.002 for fourth order; F=13.86, p<0.0001 for fifth and higher orders). More higher-order Zernike aberrations such as coma and spherical aberration were induced by cast-molded CLs and/or the spun-cast CLs. Wavefront aberrations in the eyes with soft contact lenses vary from one individual lens type to another. Although the variation in wavefront aberrations could be attributed to the differences in the methods of manufacture, influences from other factors such as the lens material and lens design could not be excluded and deserve further investigation.

Wavefront Aberrations in Eyes With Acrysof Monofocal Intraocular Lenses

To characterize and measure the ocular aberrations in eyes implanted with monofocal intraocular lenses (IOLs) and to study any correlation between postoperative aberrations and surgical factors. A Tscherning aberroscope was used to measure the wavefront aberrations of 62 eyes that had undergone phacoemulsification with the implantation of foldable monofocal Acrysof MA60BM IOLs (Alcon Laboratories Inc, Ft Worth, Tex). The Zernike coefficients, measured with a pupil diameter of 6 mm, were compared with those of a normal dataset of 82 eyes of healthy young myopes. Spherical aberration (Z(0)4) was the most predominant higher order aberration, with a mean value of 0.37 +/- 0.16 microm. A statistically significant linear relationship was noted between the magnitude of postoperative spherical aberration and the dioptric power of the IOL. The mean spherical aberration was 33 times more in the pseudophakic group than in normal young myopic eyes. The other major higher order aberrations were trefoil (Z(-3)3) with a mean of -0.13 +/- 0.22 microm and vertical coma (Z(-1)3) with a mean value of -0.11 +/- 0.23 microm. On average, the root-mean-square of higher order aberrations in pseudophakic eyes was 2.1 times that in a normal population of young myopic eyes. Eyes that undergo cataract surgery with monofocal IOL implantation suffer from significant higher order aberrations. The optical design of the IOL is most likely responsible for the increase in spherical aberration, the magnitude of which is a function of the dioptric power of the IOL.

Individual eye model based on wavefront aberration

Based on the widely used Gullstrand-Le Grand eye model, the individual human eye model has been established here, which has individual corneal data, anterior chamber depth and the eyeball depth. Furthermore, the foremost thing is that the wavefront aberration calculated from the individual eye model is equal to the eye's wavefront aberration measured with the Hartmann-shack wavefront sensor. There are four main steps to build the model. Firstly, the corneal topography instrument was used to measure the corneal surfaces and depth. And in order to input cornea into the optical model, high-order aspheric surface-Zernike Fringe Sag surface was chosen to fit the corneal surfaces. Secondly, the Hartmann-shack wavefront sensor, which can offer the Zernike polynomials to describe the wavefront aberration, was built to measure the wavefront aberration of the eye. Thirdly, the eye's axial lengths among every part were measured with A-ultrasonic technology. Then the data were input into the optical design software–ZEMAX and the crystalline lens's shapes were optimized with the aberration as the merit function. The individual eye model, which has the same wavefront aberrations with the real eye, is established.