Relevant bibliographies by topics / Higher order aberration

Academic literature on the topic 'Higher order aberration'

Author: Grafiati
Published: 4 June 2021
Last updated: 20 February 2023

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Journal articles on the topic "Higher order aberration"

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Sapkota, Kishor, Jessica Gomes, and Sandra Franco. "Effect of Accommodation on Peripheral Higher Order Aberrations." Photonics 9, no. 2 (January 26, 2022): 64. http://dx.doi.org/10.3390/photonics9020064.

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Knowledge of the effect of accommodation on image quality of peripheral retina is crucial for better understanding of the visual system, but only a few studies have been carried out in this area. This study was designed to evaluate the effect of accommodation on higher order aberrations from third to sixth Zernike polynomials in central and peripheral retina up to 23° off-axis. We used a Hartmann–Shack aberrometer to measure Zernike coefficients with both accommodated and non-accommodated eyes of 15 healthy subjects. Each Zernike coefficient, total higher order aberrations, spherical aberrations and astigmatism were compared between accommodated and non-accommodated status. Additionally, aberrations in the central retina were compared with the peripheral retina. Accommodation induced significant changes in the Zernike coefficients of vertical pentafoil C5−5 and secondary vertical tetrafoil C6−4 in central retina, secondary vertical astigmatism C4−2 on 23° of temporal retina, secondary vertical tetrafoil C6−4 and tertiary vertical astigmatism C6−2 on 10° of nasal retina, secondary vertical trefoil C5−3 and secondary vertical tetrafoil C6−4 on 23° of nasal retina, and horizontal tetrafoil C44, and secondary horizontal tetrafoil C64 on 23° of inferior retina (p < 0.05). Total higher order aberration was lower in each retinal area examined with accommodation, but it was statistically significant only on 23° temporal retina and 11.5° and 23° of superior retina (p < 0.05). Spherical aberration decreased with accommodation on 23° temporal retina (p = 0.036). Astigmatism was similar in non-accommodated and accommodated eyes. Overall, accommodation affected higher order aberration (HOA) asymmetrically in different peripheral retinal areas.
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Ximen, Jiye. "Canonical aberration theory for calculating higher‐order chromatic aberrations." Journal of Applied Physics 69, no. 4 (February 15, 1991): 1962–67. http://dx.doi.org/10.1063/1.348768.

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Lupini, Andrew R., and Stephen J. Pennycook. "Tuning Fifth-Order Aberrations in a Quadrupole-Octupole Corrector." Microscopy and Microanalysis 18, no. 4 (July 30, 2012): 699–704. http://dx.doi.org/10.1017/s1431927612001237.

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AbstractThe resolution of conventional electron microscopes is usually limited by spherical aberration. Microscopes equipped with aberration correctors are then primarily limited by higher order, chromatic, and misalignment aberrations. In particular the Nion third-order aberration correctors installed on machines with a low energy spread and possessing sophisticated alignment software were limited by the uncorrected fifth-order aberrations. Here we show how the Nion fifth-order aberration corrector can be used to adjust and reduce some of the fourth- and fifth-order aberrations in a probe-corrected scanning transmission electron microscope.
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Yu, Ying, Wenwen Zhang, Xinliang Cheng, Jianru Cai, and Hui Chen. "Impact of Treatment Decentration on Higher-Order Aberrations after SMILE." Journal of Ophthalmology 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/9575723.

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Purpose. To evaluate decentration following femtosecond laser small incision lenticule extraction (SMILE) and sub-Bowman keratomileusis (SBK) and its impact on higher-order aberrations (HOAs). Methods. Prospective, nonrandom, and comparison study. There were 96 eyes of 52 patients who received SMILE and 96 eyes of 49 patients who received SBK in this study. Decentration was calculated 6 months after surgery with Pentacam. HOAs and visual acuity after the surgery were examined for patients in both groups before and 6 months after surgery. Results. The mean decentration displacement in SMILE group was significantly less than SBK group (P=0.020). 89 eyes were decentered within 0.50 mm after SMILE and SBK. The association between vertical decentration and the induced spherical aberration was insignificant in SMILE group (P=0.035). There was an association between decentration and safety index, efficacy index, vertical coma, spherical aberration, and HOAs in root mean square (RMS, μm) after SBK (all P<0.05). No difference was found in uncorrected and corrected distance visual acuity, safety index, efficacy index, and wavefront aberrations between the two subgroups at any delimited value after SMILE (all P>0.05). Decentration exceeding 0.37 mm affected vertical coma and RMSh of SBK eyes (P=0.002, 0.005). Conclusion. SMILE surgery achieved more accurate centration than SBK surgery. Vertical decentration is associated with the induced spherical aberration in SMILE.
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Batomunkuev, Yu Ts, and A. A. Dianova. "CALCULATION OF THE HIGHER-ORDER AXIAL SPHERICAL ABERRATIONS OF A HIGH-APERTURE FOCUSING HOLOGRAPHIC OPTICAL ELEMENT WITH THE CORRECTED THIRD-ORDER SPHERICAL ABERRATION." Computer Optics 42, no. 1 (March 30, 2018): 44–53. http://dx.doi.org/10.18287/2412-6179-2018-42-1-44-53.

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Results of calculating the radius of higher-order spherical aberrations (fifth, seventh and ninth orders) of a high-aperture focusing holographic optical element (HOE) with corrected third-order spherical aberration in the operating spectral range are discussed. As examples, high-aperture axial HOEs with relative apertures close to 1:1 in specified spectral ranges are considered. Coordinates of the point sources of a divergent reference wave and a convergent object wave of the HOE are given. It is shown that when imaging a point source emitting in the 0.250-0.281-µm and 0.500- 0.563-µm spectral ranges, the use of an HOE in the first and second diffraction orders makes it is possible to correct the third-order spherical aberration on two wavelengths and the fifth- and seventh-order spherical aberrations on one wavelength. Note that these visible-spectrum wavelengths are different from the HOE's recording wavelength of 0.532 µm.
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Haigh, Sarah J., Hidetaka Sawada, Kunio Takayanagi, and Angus I. Kirkland. "Exceeding Conventional Resolution Limits in High-Resolution Transmission Electron Microscopy Using Tilted Illumination and Exit-Wave Restoration." Microscopy and Microanalysis 16, no. 4 (July 6, 2010): 409–15. http://dx.doi.org/10.1017/s1431927610093359.

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AbstractTilted illumination exit-wave restoration is compared for two aberration-corrected instruments at different accelerating voltages. The experimental progress of this technique is also reviewed and the significance of off-axial aberrations examined. Finally, the importance of higher order aberration compensation combined with careful correction of the lower order aberrations is highlighted.
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Zhao, Peng-Fei, Yue Wang, Cai-Yun Fu, Jing Zhang, and Chang-Bin Zhai. "Comparison of correcting myopia and astigmatism with SMILE or FS-LASIK and postoperative higher-order aberrations." International Journal of Ophthalmology 14, no. 4 (April 18, 2021): 523–28. http://dx.doi.org/10.18240/ijo.2021.04.07.

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AIM: To compare the effect of myopia and astigmatism correction and postoperative change in higher-order aberration as results of receiving small-incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). METHODS: A prospective and non-randomized controlled study was conducted. The subjects are divided into two groups according to different operations received: 229 eyes of 116 patients in the SMILE group and 168 eyes of 86 patients in the FS-LASIK group. All subjects were followed up for 3mo by monitoring their uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalent, higher-order aberrations, and the preoperative and postoperative complications. RESULTS: At 1wk, 1, and 3mo post-surgery, 224 eyes (97.8%), 227 eyes (99.1%) and 229 eyes (100%) had UCVA≥20/20 in the SMILE group, while 165 eyes (98.2%), 167 eyes (99.4%) and 167 eyes (99.4%) had UCVA≥20/20 in the FS-LASIK group, respectively (χ2=0.146, 2.135, and 1.124; all P&#x0026;#x003E;0.05). BCVA reduction was not observed in both groups at 1 and 3mo of post-surgery (χ2=0.734 and 1.898, P&#x0026;#x003E;0.05). There was no statistically significant difference in the spherical equivalent between the two groups at 1 and 3mo post-surgery, though the percentage of the spherical equivalent within ±0.50 D at 3mo post-surgery was 98% in the SMILE group, which was higher than that of the FS-LASIK group (92%, χ2=1.872, P&#x0026;#x003E;0.05). The root mean square (RMS) values of total high-order aberration, coma, and spherical aberration of the two groups increased significantly in the early postoperative period and decreased after 3mo, but the values were still higher than the preoperative levels (P&#x0026;#x003C;0.05); there was no significant difference between the two groups in the RMS values of total higher-order aberrations and specific higher-order aberrations (P&#x0026;#x003E;0.05). The incidence of complications in the SMILE group was lower than that in the FS-LASIK group (χ2=14.52, P&#x0026;#x003C;0.05). CONCLUSION: SMILE and FS-LASIK can effectively treat myopia, significantly improve visual acuity, and increase the total high-order aberration, spherical aberration, and coma. The incidence of complications after SMILE is relatively low.
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Anbar, Mohamed, Engy Mohamed Mostafa, Ashraf Mostafa Elhawary, Islam Awny, Mahmoud Mohamed Farouk, and Amr Mounir. "Evaluation of Corneal Higher-Order Aberrations by Scheimpflug–Placido Topography in Patients with Different Refractive Errors: A Retrospective Observational Study." Journal of Ophthalmology 2019 (June 2, 2019): 1–5. http://dx.doi.org/10.1155/2019/5640356.

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Purpose. To report the characteristics of anterior and posterior corneal high-order aberrations in patients with different refractive errors.Setting. This study was conducted at Sohag Refractive Center, Sohag, Egypt.Design. This is a retrospective observational study.Methods. This study evaluated 750 patients (750 eyes) who were seeking refractive surgery. The eyes were stratified into five groups (150 eyes/group) based on refractive error: mild-to-moderate myopia, high myopia, hyperopia, simple myopic astigmatism, and simple hypermetropic astigmatism. All patients were subjected to comprehensive ophthalmological examination including corneal topography and corneal aberrometry using the Scheimpflug–Placido topography (Sirius, CSO, Italy).Results. Coma aberration was statistically significant when compared in all five groups (P=0.01). It was highest in the hypermetropia group (0.26 ± 0.12 μm) but lower in the moderate myopia, high myopia, myopic astigmatism, and hypermetropic astigmatism groups. Spherical aberration was lowest in the hypermetropia group and significantly different from that in the other groups. Trefoil was statistically insignificant when all groups were compared (P=0.062) but was highest in the myopic astigmatism group (0.24 ± 0.25 μm). Total RMS peaked in the hypermetropia group (0.99 ± 0.70).Conclusions. In normal corneas and regular refractive errors, the cornea-induced high-order aberration was minimal, and all types of refractive errors were associated with certain types of high-order aberrations, with a significant increase in spherical aberration in the hypermetropia group.
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Brenner, Luis F. "Corneal higher-order aberrations and higher-order Strehl ratio after aberration-free ablation profile to treat compound myopic astigmatism." Journal of Cataract & Refractive Surgery 41, no. 12 (December 2015): 2672–82. http://dx.doi.org/10.1016/j.jcrs.2015.06.035.

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Erdem, Uzeyir, Fatih C. Gundogan, Umut Aslı Dinc, Umit Yolcu, Abdullah Ilhan, and Salih Altun. "Acute Effect of Cigarette Smoking on Pupil Size and Ocular Aberrations: A Pre- and Postsmoking Study." Journal of Ophthalmology 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/625470.

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Aim.To evaluate the acute effects of cigarette smoking on photopic and mesopic pupil sizes and wavefront aberrations.Methods.Cigarette smoker volunteers were recruited in the study. Photopic and mesopic pupil sizes and total ocular aberrations were measured before smoking and immediately after smoking. All volunteers were asked to smoke a single cigarette containing 1.0 mg nicotine. Pupil sizes and total ocular aberrations were assessed by optical path difference scanning system (OPD-Scan II ARK-10000, NIDEK). Only the right eyes were considered for statistical analysis. The changes of pupil size and total ocular aberrations after smoking were tested for significance by Wilcoxon signed ranks test.Results.Mean photopic pupil size decreased from 3.52 ± 0.73 mm to 3.29 ± 0.58 mm(P=0.001)after smoking. Mean mesopic pupil size was also decreased from 6.42 ± 0.75 mm to 6.14 ± 0.75 mm after smoking(P=0.001). There was a decrease in all the measured components of aberrations (total wavefront aberration, higher-order aberration, total coma, total trefoil, total tetrafoil, total spherical aberration and total higher-order aberration) after smoking; however the differences were insignificant for all(P>0.05).Conclusion.Our results indicate that pupil constricts after smoking. On the other hand, smoking does not alter ocular aberrations.
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Dissertations / Theses on the topic "Higher order aberration"

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Yi, Fan. "Wavefront aberrations and the depth of focus of the human eye." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/40939/1/Fan_Yi_Thesis.pdf.

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The depth of focus (DOF) can be defined as the variation in image distance of a lens or an optical system which can be tolerated without incurring an objectionable lack of sharpness of focus. The DOF of the human eye serves a mechanism of blur tolerance. As long as the target image remains within the depth of focus in the image space, the eye will still perceive the image as being clear. A large DOF is especially important for presbyopic patients with partial or complete loss of accommodation (presbyopia), since this helps them to obtain an acceptable retinal image when viewing a target moving through a range of near to intermediate distances. The aim of this research was to investigate the DOF of the human eye and its association with the natural wavefront aberrations, and how higher order aberrations (HOAs) can be used to expand the DOF, in particular by inducing spherical aberrations ( 0 4 Z and 0 6 Z ). The depth of focus of the human eye can be measured using a variety of subjective and objective methods. Subjective measurements based on a Badal optical system have been widely adopted, through which the retinal image size can be kept constant. In such measurements, the subject.s tested eye is normally cyclopleged. Objective methods without the need of cycloplegia are also used, where the eye.s accommodative response is continuously monitored. Generally, the DOF measured by subjective methods are slightly larger than those measured objectively. In recent years, methods have also been developed to estimate DOF from retinal image quality metrics (IQMs) derived from the ocular wavefront aberrations. In such methods, the DOF is defined as the range of defocus error that degrades the retinal image quality calculated from the IQMs to a certain level of the possible maximum value. In this study, the effect of different amounts of HOAs on the DOF was theoretically evaluated by modelling and comparing the DOF of subjects from four different clinical groups, including young emmetropes (20 subjects), young myopes (19 subjects), presbyopes (32 subjects) and keratoconics (35 subjects). A novel IQM-based through-focus algorithm was developed to theoretically predict the DOF of subjects with their natural HOAs. Additional primary spherical aberration ( 0 4 Z ) was also induced in the wavefronts of myopes and presbyopes to simulate the effect of myopic refractive correction (e.g. LASIK) and presbyopic correction (e.g. progressive power IOL) on the subject.s DOF. Larger amounts of HOAs were found to lead to greater values of predicted DOF. The introduction of primary spherical aberration was found to provide moderate increase of DOF while slightly deteriorating the image quality at the same time. The predicted DOF was also affected by the IQMs and the threshold level adopted. We then investigated the influence of the chosen threshold level of the IQMs on the predicted DOF, and how it relates to the subjectively measured DOF. The subjective DOF was measured in a group of 17 normal subjects, and we used through-focus visual Strehl ratio based on optical transfer function (VSOTF) derived from their wavefront aberrations as the IQM to estimate the DOF. The results allowed comparison of the subjective DOF with the estimated DOF and determination of a threshold level for DOF estimation. Significant correlation was found between the subject.s estimated threshold level for the estimated DOF and HOA RMS (Pearson.s r=0.88, p<0.001). The linear correlation can be used to estimate the threshold level for each individual subject, subsequently leading to a method for estimating individual.s DOF from a single measurement of their wavefront aberrations. A subsequent study was conducted to investigate the DOF of keratoconic subjects. Significant increases of the level of HOAs, including spherical aberration, coma and trefoil, can be observed in keratoconic eyes. This population of subjects provides an opportunity to study the influence of these HOAs on DOF. It was also expected that the asymmetric aberrations (coma and trefoil) in the keratoconic eye could interact with defocus to cause regional blur of the target. A dual-Badal-channel optical system with a star-pattern target was used to measure the subjective DOF in 10 keratoconic eyes and compared to those from a group of 10 normal subjects. The DOF measured in keratoconic eyes was significantly larger than that in normal eyes. However there was not a strong correlation between the large amount of HOA RMS and DOF in keratoconic eyes. Among all HOA terms, spherical aberration was found to be the only HOA that helped to significantly increase the DOF in the studied keratoconic subjects. Through the first three studies, a comprehensive understanding of DOF and its association to the HOAs in the human eye had been achieved. An adaptive optics system was then designed and constructed. The system was capable of measuring and altering the wavefront aberrations in the subject.s eye and measuring the resulting DOF under the influence of different combination of HOAs. Using the AO system, we investigated the concept of extending the DOF through optimized combinations of 0 4 Z and 0 6 Z . Systematic introduction of a targeted amount of both 0 4 Z and 0 6 Z was found to significantly improve the DOF of healthy subjects. The use of wavefront combinations of 0 4 Z and 0 6 Z with opposite signs can further expand the DOF, rather than using 0 4 Z or 0 6 Z alone. The optimal wavefront combinations to expand the DOF were estimated using the ratio of increase in DOF and loss of retinal image quality defined by VSOTF. In the experiment, the optimal combinations of 0 4 Z and 0 6 Z were found to provide a better balance of DOF expansion and relatively smaller decreases in VA. Therefore, the optimal combinations of 0 4 Z and 0 6 Z provides a more efficient method to expand the DOF rather than 0 4 Z or 0 6 Z alone. This PhD research has shown that there is a positive correlation between the DOF and the eye.s wavefront aberrations. More aberrated eyes generally have a larger DOF. The association of DOF and the natural HOAs in normal subjects can be quantified, which allows the estimation of DOF directly from the ocular wavefront aberration. Among the Zernike HOA terms, spherical aberrations ( 0 4 Z and 0 6 Z ) were found to improve the DOF. Certain combinations of 0 4 Z and 0 6 Z provide a more effective method to expand DOF than using 0 4 Z or 0 6 Z alone, and this could be useful in the optimal design of presbyopic optical corrections such as multifocal contact lenses, intraocular lenses and laser corneal surgeries.
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Yi, Fan, and n/a. "Optimal Algorithmic Techniques of LASIK Procedures." Griffith University. School of Engineering, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070216.152339.

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Clinical wavefront-guided corneal ablation has been now the most technologically advanced method to reduce the dependence of glasses and contact lenses. It has the potential not only to eliminate spherocylindrical errors but also to reduce higher-order aberrations (HOA). Recent statistics show that more than 96% of the patients who received laser in situ keratomileusis (LASIK) treatment reported their satisfaction about the improvement on vision, six months after the surgery. However, there are still patients complaining that their vision performance did not achieve the expectation or was even worse than before surgery. The reasons causing the unexpected post-surgical outcome include undercorrection, overcorrection, induced HOA, and other postoperative diseases, most of which are caused by inaccurate ablation besides other pathological factors. Therefore, to find out the method to optimize the LASIK procedures and provide a higher surgical precision has become increasingly important. A proper method to calculate ablation profile and an effective way to control the laser beam size and shape are key aspects in this research to resolve the problem. Here in this Master of Philosophy degree thesis, the author has performed a meticulous study on the existing methods of ablation profile calculation and investigated the efficiency of wavefront only ablation by a computer simulation applying real patient data. Finally, the concept of a refractive surgery system with dynamical beam shaping function is sketched, which can theoretically overcome the disadvantages of traditional procedures with a finite laser beam size.
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Yi, Fan. "Optimal Algorithmic Techniques of LASIK Procedures." Thesis, Griffith University, 2006. http://hdl.handle.net/10072/368097.

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Clinical wavefront-guided corneal ablation has been now the most technologically advanced method to reduce the dependence of glasses and contact lenses. It has the potential not only to eliminate spherocylindrical errors but also to reduce higher-order aberrations (HOA). Recent statistics show that more than 96% of the patients who received laser in situ keratomileusis (LASIK) treatment reported their satisfaction about the improvement on vision, six months after the surgery. However, there are still patients complaining that their vision performance did not achieve the expectation or was even worse than before surgery. The reasons causing the unexpected post-surgical outcome include undercorrection, overcorrection, induced HOA, and other postoperative diseases, most of which are caused by inaccurate ablation besides other pathological factors. Therefore, to find out the method to optimize the LASIK procedures and provide a higher surgical precision has become increasingly important. A proper method to calculate ablation profile and an effective way to control the laser beam size and shape are key aspects in this research to resolve the problem. Here in this Master of Philosophy degree thesis, the author has performed a meticulous study on the existing methods of ablation profile calculation and investigated the efficiency of wavefront only ablation by a computer simulation applying real patient data. Finally, the concept of a refractive surgery system with dynamical beam shaping function is sketched, which can theoretically overcome the disadvantages of traditional procedures with a finite laser beam size.
Thesis (Masters)
Master of Philosophy (MPhil)
School of Engineering
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Jinabhai, Amit. "Higher-order aberrations in keratoconus." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/higherorder-aberrations-in-keratoconus(32fcb499-fd7a-4764-b723-f58ef1a22633).html.

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The reduction in visual performance typically found in keratoconic patients is believed to be associated with large magnitudes of uncorrected irregular astigmatism and higher-order aberrations (HOAs). Previous studies indicate that correcting HOAs in keratoconus patients may result in an improvement in visual performance. This thesis explores the correction of HOAs using standard sphero-cylindrical and customised aberration-controlling soft contact lenses in 22 patients with keratoconus. The findings of this work may be useful from a clinical perspective, as some keratoconic patients cannot tolerate rigid gas-permeable (RGP) contact lenses and have few alternatives, excluding surgical intervention, for vision correction. This thesis firstly describes a series of preliminary studies conducted to improve our current understanding of the HOAs manifested in keratoconus. The results of these investigations suggested that alterations in aberrations, due to changes in accommodation or variations in the pre-corneal tear film post-blink, were unlikely to hinder the correction of HOAs for keratoconic patients. Equally, it was ascertained that subjective refraction data provided significantly better visual acuity compared to objective, aberrometry-derived refractions for patients with keratoconus. The findings also show that both lower-order aberrations (LOAs) and HOAs displayed a larger degree of variability in keratoconic eyes compared to those previously reported for visually-normal subjects. Furthermore, significant increases in 3rd-order coma root mean square aberrations were found after temporarily suspending RGP contact lens wear for 16 keratoconic patients. The results of two clinical studies suggested that standard sphero-cylindrical soft lenses can, to some extent, mask HOAs in keratoconic patients; however, the visual performances achieved were found to be poorer compared to RGP lenses. Equally, the results showed that RGP lenses provide superior visual performances compared to customised, aberration-controlling lenses, in spite of the customised lenses providing comparable reductions in uncorrected HOAs. The inducement of superfluous HOAs and LOAs, through customised contact lens translations and rotations, were modelled using MatLab (version 7.6.0.324; The Mathworks, Natick, MA, US). The results confirmed that minimising the decentration of aberration-controlling contact lenses, to less than 5 degrees of rotation and less than 0.50 mm of translation, will help to achieve an optimal correction of HOAs. However, more stringent criteria were required for LOAs, where rotational displacements should be reduced to less than 3 degrees and translational displacements should be limited to less than 0.10 mm. In conclusion, the correction of HOAs for patients with keratoconus is possible using customised, aberration-controlling soft contact lenses; however, several factors will govern their success, including the repeatability and accuracy of HOA measurements for these irregular corneas, and the stability of the customised lenses on-eye.
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Young, Laura Kate. "Ocular higher-order aberrations and visual performance." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/3282/.

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Since adaptive optics was first used to correct the monochromatic aberrations of the eye over a decade ago there has been considerable interest in correcting the ocular aberrations beyond defocus and astigmatism. In order to understand the prospective benefits of correcting these higher-order aberrations it is important to study their effect on visual performance. From a clinical perspective it is important to know how different types of aberration can affect visual performance so that wavefront measurements can be better understood. Visual performance is determined by a combination of optical and neural factors. It is important to consider how degradations in the optical quality of the eye can impact the neural processes involved in visual tasks such as object recognition. In this thesis we present a study of the effects of three types of aberration, defocus, coma and secondary astigmatism, on letter recognition and reading performance. In the course of this work we also characterise the repeatability of the Zywave aberrometer, which we used to measure our subjects' ocular wavefronts. We use stimuli that have these aberrations applied in their rendering to examine the differences between these aberrations and how they differ with respect to the visual task. We find that secondary astigmatism causes the largest impairment to both letter recognition and reading performance, followed by defocus. Coma causes comparatively smaller degradations to performance but its effect is different depending on the visual task. We can predict the reduction in performance based on a simple cross-correlation model of letter confusability. The relationship between these predictions and the experimental results are the same for all three aberrations, in the case of single letter recognition. In reading however, the relationship is different for coma. We suggest that coma causes lateral masking effects and may additionally disrupt the planning of eye movements. Coma slows reading, but does not specifically impair word identification whereas defocus and secondary astigmatism do. We attribute disruptions in word identification to the dramatic effects defocus and secondary astigmatism have on the form of a letter.
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Tahir, Humza. "The impact of higher-order aberrations on orientation selectivity." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493940.

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This thesis describes a set of experiments investigating the impact of the higher-order aberrations of the eye on contrast sensitivity. The principal aim is to investigate if asymmetric blur induced by the aberrations of the eye can produce orientation selective effects. Orientation in contrast sensitivity testing has been largely ignored as it has been thought that the oblique effect, the preference for vertical and horizontal stimuli over obliques, was entirely neural in origin. Studies measuring the oblique effect were conducted using diffraction-limited pupils yet in larger pupils the higher order aberrations have an increasing impact on visual performance. These aberrations can be circularly asymmetric and so this raises the possibility that they may influence orientation selectivity when the pupil is large. The second aim of the study is to investigate orientation selective contrast sensitivity in refractive surgery patients.
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McCullough, Sara. "Higher order ocular aberrations in children with Down's syndrome." Thesis, University of Ulster, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589518.

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Background Down's syndrome CDS) is the most common cause of learning disability in humans. Studies have described deficits in visual performance in DS that cannot be explained by ocular pathology, refractive errors, attentional or behavioural factors. Structural differences in the optics of the DS eye have been reported. It has also been previously reported that visual performance in DS is significantly improved when the optics of the eye are by-passed, suggesting an underlying optical defect. This thesis investigates whether optical quality is reduced in children with DS and how an optical deficit might influence their visual function. Methods Forty-four children with DS and 211 age-matched typically developing children participated in the main study. Optical quality was quantified by the measurement of higher order aberrations. Ocular structure and shape were also assessed to explore their influence on higher order aberrations and optical quality. Higher order aberrations were compared with visual performance measures of high and low contrast recognition acuity, grating resolution acuity and accommodative function. Higher order aberrations were also analysed for a large group of typically developing white Northern Irish children to explore the influences of age and refractive error on these measurements. Results & Conclusions The data demonstrated that: • Children with DS have greater levels of higher order aberrations and poorer optical quality than typically developing children. These differences were not attributable to greater levels of ametropia or premature aging in DS. • The data suggest multiple limitations of visual function in children with DS including optical and neural factors. • Neural adaptation and compensation of retinal image blur may be lacking or less efficient in DS resulting in poorer visual performance. • Negative spherical aberration found in the children with DS may indicate that differences in crystalline lens shape may restrict accommodative ability.
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Mishor, Gabriel. "Higher order aberrations and age-related cataract : a pre- and post- operative study." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/39687/.

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The outcome of higher order aberrations (HOAs) prior to, and following, age-related cataract extraction and intra-ocular lens (IOL) implantation was explored using placido disc skiaoscopy aberrometry. Ninety-nine individuals (median age 73.0, IQR 67.0, 80.5) underwent comprehensive ophthalmic examination including contrast sensitivity, endothelial cell imaging and aberrometry (Nidek OPD ARK-10000) at approximately 4 weeks pre-operatively (median 3.9, IQR 2.9, 4.8) 10 weeks (median 7.1, IQR 5.64, 11.71) (67 individuals) and 80 weeks (median 85.1, IQR 80.0, 89.6) (41 individuals) post-operatively. Linear relationships between thirteen demographical, functional and structural variables and each of three components, Total (TC), Corneal (CC) and Internal (IC), for each of eight HOAs, were separately explored, using Analysis of Variance, for each examination and for the pre- and post-operative differences, respectively. The TC and IC of all HOAs decreased post-operatively (p≤68%). Preoperatively, the TC and IC of the Total HOA decreased as the spherical equivalent (SE) became less negative (both p<0.001, R2=0.56 and 0.53). Both components of the Total HOA also decreased as the difference in SE between baseline and each follow-up became less negative (all p≤0.008, R2=0.45-0.61); the magnitude of the reduction varied between IOL type (p≤0.008). The IC of the Tilt, T.Sph and HiAstig HOAs increased with increase in severity of posterior subcapsular (p=0.018), of cortical (p=0.013) and of combined nuclear colour and cortical cataract (p=0.003), respectively. The relationship between cataract type and severity and reduction in post-operative HOA was not statistically significant at either follow-up examination. Slight associations, presumably due to post-operative corneal oedema, were present between increase in CCs of five HOAs and decreasing endothelial cell density at the first follow-up, only, (all p≤0.030, R2=0.09-0.14). Pre-operative TCs and ICs were larger, respectively, than those of 22 individuals with ‘less severe’ cataract and post-operatively than those of 49 individuals with clear media, obtained from retrospective data.
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Esser, Gregor. "Derivation of analytical refraction, propagation and reflection equations for higher order aberrations of wavefronts." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/125065.

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Derivation of analytical refraction, propagation and reflection equations for Higher Order Aberrations of wavefronts From literature the analytical calculation of Lower Order Aberrations (LOA) of a wavefront after refraction, propagation and reflection is well-known, it is for local Power and Astigmatism performed by the Coddington equation for refraction and reflection and the classical vertex correction formula for propagation. However, equivalent analytical equations for Higher Order aberrations (HOA) do not exist. Since HOA play an increasingly important role in many fields of optics, e.g. ophthalmic optics, it is the purpose of this study to extend the analytical Generalized Coddington Equation and the analytical Transfer Equation, which deals with second order aberration, to the case of HOA (e.g. Coma and Spherical Aberration). This is achieved by local power series expansions. The purpose of this PhD was to extend the analytical Generalized Coddington Equation and the analytical Transfer Equation, which deals with Lower Order Aberrations (power and astigmatism), to the case of Higher Order Aberrations (e.g. Coma and Spherical Aberration). In summary, with the novel results presented here, it is now possible to calculate analytically the aberrations of an outgoing wavefront directly from the aberrations of the incoming wavefront and the refractive or reflective surface and the aberrations of a propagated wavefront directly from the aberrations of the original wavefront containing both low-order and high-order aberrations.
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Hampson, Karen Mary. "The higher-order aberrations of the human eye : connection with the pulse and effect on vision." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415452.

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Books on the topic "Higher order aberration"

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Cleary, Georgia, Allon Barsam, and Eric Donnenfeld. Refractive surgery. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199672516.003.0004.

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In a perfect optical system, a point source of light is focused onto a single point on the image plane; in the eye, light is focused on the retina. Optical aberrations are caused by imaging system imperfections which cause deviations in the transmission of light, preventing the convergence of light to a single point of focus. In recent years an increased understanding of higher-order wavefront aberrations has allowed improvements in both the measurement and treatment of refractive error. This chapter discusses refractive surgery. It details refractive error, aberrations, and presbyopia, along with preoperative evaluation for refractive surgery, laser refractive surgery, other corneal refractive procedures, refractive lens surgery, intraocular lenses, phakic intraocular lenses, and presbyopia correction.
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Mundale, Jennifer, and Shaun Gallagher. Delusional Experience. Edited by John Bickle. Oxford University Press, 2009. http://dx.doi.org/10.1093/oxfordhb/9780195304787.003.0021.

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This article presents a model of delusional experience which provides an integrated approach in which aberrations at the neurological level are directly related to a disorder of experience. It argues that higher order cognitive effects are not the proper locus for the explanation of the delusional experience itself. Through following out the neurological and phenomenological underpinnings of misattribution, this article provides a bottom-up account of the genesis of schizophrenic delusions, particularly those involving the misattributions of agency.
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Book chapters on the topic "Higher order aberration"

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Thapa, Damber, William R. Bobier, Kaamran Raahemifar, and Vasudevan Lakshminarayanan. "Is Higher Order Aberration Associated with Reduced Visual Acuity in Children?" In Springer Proceedings in Physics, 81–88. New Delhi: Springer India, 2015. http://dx.doi.org/10.1007/978-81-322-2367-2_11.

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Romano, Antonio, and Roberto Cavaliere. "About Higher Order Aberrations." In Geometric Optics, 91–105. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-43732-3_4.

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Bühren, Jens. "Higher-Order Aberrations, Refractive Surgery." In Encyclopedia of Ophthalmology, 1–2. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-642-35951-4_434-5.

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Bühren, Jens. "Higher-Order Aberrations, Refractive Surgery." In Encyclopedia of Ophthalmology, 871–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2018. http://dx.doi.org/10.1007/978-3-540-69000-9_434.

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Hazra, Lakshminarayan. "Higher Order Aberrations in Practice." In Foundations of Optical System Analysis and Design, 417–27. New York: CRC Press, 2022. http://dx.doi.org/10.1201/9780429154812-13.

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Prakash, Gaurav. "Higher Order Aberrations: Differences Among Populations from Various Demographics." In Essentials in Ophthalmology, 321–27. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-9184-6_23.

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Katsanevaki, Vikentia J., Veronica Vargas Fragoso, and Jorge L. Alio. "Causes of Higher-Order Aberrations Induction in Excimer Laser Surgery." In Management of Complications in Refractive Surgery, 155–61. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-60561-6_20.

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Velázquez, Jose Sebastián, Francisco Cavas, Jose Miguel Bolarín, and Jorge Alió. "Comparison of Corneal Morphologic Parameters and High Order Aberrations in Keratoconus and Normal Eyes." In Bioinformatics and Biomedical Engineering, 87–97. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45385-5_8.

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Yang, Fan, Jianqi Cai, Ya Guo, Qianxiang Zhou, and Zhongqi Liu. "Based on High Order Aberration Analysis of Influence Index of Vision Fatigue by Watching 3D TV." In Design, User Experience, and Usability: Novel User Experiences, 663–69. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-40355-7_64.

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Alonso, Miguel, Armando Barreto, Malek Adjouadi, and Julie A. Jacko. "HOWARD: High-Order Wavefront Aberration Regularized Deconvolution for Enhancing Graphic Displays for Visually Impaired Computer Users." In Lecture Notes in Computer Science, 1163–70. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11788713_168.

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Conference papers on the topic "Higher order aberration"

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Shafer, David R. "Six-element lens corrected for all third-and fifth-order aberrations." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/oam.1993.tht.4.

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In a well-corrected complex lens system, with a fairly fast aperture and wide field of view, the image aberrations which limit performance are usually sagittal oblique spherical aberration and higher-order Petzval curvature. Because of aberration balancing in any well-optimized design, it may not be apparent that these two 5th-order aberrations are in fact the limiting aberrations. It is not generally recognized that it is possible to correct all the 3rd and 5th-order monochromatic aberrations to zero in relatively simple designs, without aspherics. Several years ago I found an 8-element solution and more recently several 7-element designs. Now I have found two different 6-element solutions. One has no thick lenses or strong meniscus shapes and can also be corrected for axial and lateral color with no additional elements. I suspect there may be a five-lens solution, without color correction, that would involve some thick lenses.
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Shafer, David. "Distortion: the culprit exposed." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.mt5.

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Jan Hoogland has shown that fifth-order Petzval curvature is often the limiting aberration of a high-performance design, although this fact is often masked by higher-order astigmatism. I have shown that this fifth-order Petzval curvature is usually caused by pupil aberrations—mainly coma of the chief ray—within the lens. This same pupil aberration is intimately connected to the third-order distortion of the system, which is also a chief ray aberration.
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Tang, Ziyao, and Herbert Gross. "Higher-order aberration analysis in symmetry-free optical systems." In Optical Design and Engineering VIII, edited by James Babington, Ulrike Fuchs, and Laurent Mazuray. SPIE, 2021. http://dx.doi.org/10.1117/12.2596127.

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Yoon, Geun-Young, and David R. Williams. "Visual benefit of correcting the higher order monochromatic aberrations and the chromatic aberration in the eye." In Vision Science and its Applications. Washington, D.C.: OSA, 2000. http://dx.doi.org/10.1364/vsia.2000.pd5.

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Herloski, Robert. "Comprehensive Theory of Primary and Secondary Color Correction of Arbitrary Optical Systems." In International Optical Design Conference. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/iodc.1994.atpm.125.

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A method of calculating and correcting primary and higher order chromatic aberrations of arbitrary optical systems is discussed. This method uses Buchdahl’s chromatic aberration theory [1] to calculate the exact chromatic aberration coefficients (axial and lateral color of any order) of a given optical system, with no restriction on element thickness or spacing. This theory is rewritten so that the color correction problem is approximated by a series of homogeneous linear equations, which can be solved by graphical or linear algebraic techniques. This formulation gives a lens designer the ability to easily and systematically choose glasses that can potentially correct the chromatic aberrations of a complex lens system. Several design examples are given that illustrate the application of this method to lens systems with finite element thicknesses and separations. It is shown that this method can directly accommodate diffractive optical elements (DOE’s) and that DOE’s can be used to correct higher order chromatic aberrations of lens systems that could not otherwise be corrected.
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Nishi, Hisami. "Aberration analysis of a gradient-index lens with unit magnification." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.tuu22.

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The radial gradient-index rod lens array with unit magnification called SLA has been widely utilized in copy machines, LED printers, image scanners, and facsimiles as an imaging lens system of unit magnification, but the theoretical resolution limit analysis of SLA has not been defined. A theoretical resolution limit analysis of a radial gradient-index lens element has now been studied. Results of the first-order analysis are as follows: (1) an SLA with higher view angle had a higher resolution limit, (2) the meridional spot size increased in the peripheral zone of an image field because of vignetting. (3) A third-order aberration analysis has been done. In this analysis, not numerical but analytical aberration coefficient polynomials have been successfully obtained based on Moore and Sands.1 Using these polynomials, the ray intercept curve was calculated without ray tracing through the lens medium. Results of the third-order analysis were as follows: (1) all aberrations were proportional to the square of the view angle; (2) spherical aberration and Petzval curvature were dominant; (3) astigmatism had a small effect for ray error; and (4) by optimizing high-order index coefficients, blur of the peripheral zone of the image field was improved.
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Rosete-Aguilar, M. "Aspheric achromatic corrector plates for the correction of higher order chromatic aberration." In 16th Congress of the International Commission for Optics: Optics as a Key to High Technology. SPIE, 1993. http://dx.doi.org/10.1117/12.2308488.

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Nomura, Hiroshi, Kazuo Tawarayama, and Takuya Kohno. "Higher-order aberration measurement with printed patterns under extremely reduced sigma illumination." In Microlithography '99, edited by Luc Van den Hove. SPIE, 1999. http://dx.doi.org/10.1117/12.354348.

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Maxwell, Jonathan. "Aberration Calculation Methods and Aberration Correction Strategies for the Design of Apochromatic Optical Systems." In International Optical Design Conference. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/iodc.1994.atpm.144.

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The correction of higher order chromatic aberrations in high performance wide spectral band optical systems is the main barrier to achieving improved performance. These higher order chromatic aberrations appear in the form of longitudinal secondary spectrum, transverse secondary spectrum and chromatic variations of the monochromatic aberrations. The origins of some of the chromatic variation aberrations are discussed and some analysis methods for these aberrations are reviewed, with some suggestions for simple extensions to the methods that can be used for their calculation.
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Cheng, Xuemin, Yongtian Wang, and Qun Hao. "Optimization of high-numerical-aperture objectives by splitting a singlet with control of higher-order aberration." In ICO20:Optical Design and Fabrication, edited by James Breckinridge and Yongtian Wang. SPIE, 2006. http://dx.doi.org/10.1117/12.668149.

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