Publications by authors named "Arne Ohlendorf"

36 Publications

Application of big-data for epidemiological studies of refractive error.

PLoS One 2021 23;16(4):e0250468. Epub 2021 Apr 23.

Centre for Eye Research Ireland, School of Physics and Clinical and Optometric Sciences, Technological University Dublin, Dublin, Ireland.

Purpose: To examine whether data sourced from electronic medical records (EMR) and a large industrial spectacle lens manufacturing database can estimate refractive error distribution within large populations as an alternative to typical population surveys of refractive error.

Subjects: A total of 555,528 patient visits from 28 Irish primary care optometry practices between the years 1980 and 2019 and 141,547,436 spectacle lens sales records from an international European lens manufacturer between the years 1998 and 2016.

Methods: Anonymized EMR data included demographic, refractive and visual acuity values. Anonymized spectacle lens data included refractive data. Spectacle lens data was separated into lenses containing an addition (ADD) and those without an addition (SV). The proportions of refractive errors from the EMR data and ADD lenses were compared to published results from the European Eye Epidemiology (E3) Consortium and the Gutenberg Health Study (GHS).

Results: Age and gender matched proportions of refractive error were comparable in the E3 data and the EMR data, with no significant difference in the overall refractive error distribution (χ2 = 527, p = 0.29, DoF = 510). EMR data provided a closer match to the E3 refractive error distribution by age than the ADD lens data. The ADD lens data, however, provided a closer approximation to the E3 data for total myopia prevalence than the GHS data, up to age 64.

Conclusions: The prevalence of refractive error within a population can be estimated using EMR data in the absence of population surveys. Industry derived sales data can also provide insights on the epidemiology of refractive errors in a population over certain age ranges. EMR and industrial data may therefore provide a fast and cost-effective surrogate measure of refractive error distribution that can be used for future health service planning purposes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0250468PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8064549PMC
April 2021

Comparison of Methods for Estimating Retinal Shape: Peripheral Refraction vs. Optical Coherence Tomography.

J Clin Med 2021 Jan 6;10(2). Epub 2021 Jan 6.

Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany.

Retinal shape presents a clinical parameter of interest for myopia, and has commonly been inferred indirectly from peripheral refraction (PRX) profiles. Distortion-corrected optical coherence tomography (OCT) scans offer a new and direct possibility for retinal shape estimation. The current study compared retinal curvatures derived from OCT scans vs. PRX measurements in three refractive profiles (0° and 90° meridians, plus spherical equivalent) for 25 participants via Bland-Altman analysis. The radial differences between both procedures were correlated to axial length using Pearson correlation. In general, PRX- and OCT-based retinal radii showed low correlation (all intraclass correlation coefficients < 0.21). PRX found flatter retinal curvatures compared to OCT, with the highest absolute agreement found with the 90° meridian (mean difference +0.08 mm) and lowest in the 0° meridian (mean difference +0.89 mm). Moreover, a negative relation between axial length and the agreement of both methods was detected especially in the 90° meridian (R = -0.38, = 0.06). PRX measurements tend to underestimate the retinal radius with increasing myopia when compared to OCT measurements. Therefore, future conclusions from PRX on retinal shape should be made cautiously. Rather, faster and more clinically feasible OCT imaging should be performed for this purpose.
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http://dx.doi.org/10.3390/jcm10020174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7825350PMC
January 2021

Advancing Digital Workflows for Refractive Error Measurements.

J Clin Med 2020 Jul 12;9(7). Epub 2020 Jul 12.

Institute for Ophthalmic Research, Center for Ophthalmology, Eberhard Karls University of Tuebingen, Elfriede-Aulhorn-Straße 7, 72076 Tuebingen, Germany.

Advancements in clinical measurement of refractive errors should lead to faster and more reliable measurements of such errors. The study investigated different aspects of advancements and the agreement of the spherocylindrical prescriptions obtained with an objective method of measurement ("Aberrometry" (AR)) and two methods of subjective refinements ("Wavefront Refraction" (WR) and "Standard Refraction" (StdR)). One hundred adults aged 20-78 years participated in the course of the study. Bland-Altman analysis of the right eye measurement of the spherocylindrical refractive error (M) identified mean differences (±95% limits of agreement) between the different types of measurements of +0.36 D (±0.76 D) for WR vs. AR (-test: < 0.001), +0.35 D (± 0.84 D) for StdR vs. AR (-test: < 0.001), and 0.0 D (± 0.65 D) for StdR vs. WR (-test: < 0.001). Monocular visual acuity was 0.0 logMAR in 96% of the tested eyes, when refractive errors were corrected with measurements from AR, indicating that only small differences between the different types of prescriptions are present.
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http://dx.doi.org/10.3390/jcm9072205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7408987PMC
July 2020

Myopia induces meridional growth asymmetry of the retina: a pilot study using wide-field swept-source OCT.

Sci Rep 2020 07 2;10(1):10886. Epub 2020 Jul 2.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, 72076, Tübingen, Germany.

Myopic axial eye growth has mechanical implications on ocular structures, such as the retinal and foveal shape integrity or choroidal thickness. The current study investigated myopia-related changes of retinal radius of curvature, foveal width, depth, slope and choroidal thickness. Wide-field swept-source OCT line and volume scans were performed on 40 young adult participants in horizontal and vertical directions. OCT scans were corrected for their scan display distortions before automated extraction of retinal and foveal shape parameters. All findings were correlated to refractive error and axial length. The horizontal retinal radius of curvature and the directional ratio between horizontal and vertical retinal shape correlated significantly with axial length ([Formula: see text] and [Formula: see text]). Vertical retinal shape and foveal pit parameters neither showed any significant correlations with axial length nor refractive error (all [Formula: see text] 0.05). Choroidal thickness correlated significantly with refractive error in all analyzed regions ([Formula: see text]), but less with axial length ([Formula: see text] to - 0.37). Horizontal retinal shape and choroidal thickness, but not foveal pit morphology, were altered by myopic eye growth. Asymmetries in horizontal versus vertical retinal shape with increasing myopia were detected. These parameters could act as promising biomarkers for myopia and its associated complications.
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http://dx.doi.org/10.1038/s41598-020-67940-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7331682PMC
July 2020

To Correct or Not Correct? Actual Evidence, Controversy and the Questions That Remain Open.

J Clin Med 2020 Jun 24;9(6). Epub 2020 Jun 24.

Carl Zeiss Vision International GmbH, ZEISS Group, Turnstrasse 27, 73430 Aalen, Germany.

Clinical studies and basic research have attempted to establish a relationship between myopia progression and single vision spectacle wear, albeit with unclear results. Single vision spectacle lenses are continuously used as the control group in myopia control trials. Hence, it is a matter of high relevance to investigate further whether they yield any shift on the refractive state, which could have been masked by being used as a control. In this review, eye development in relation to eyes fully corrected versus those under-corrected is discussed, and new guidelines are provided for the analysis of structural eye changes due to optical treatments. These guidelines are tested and optimised, while ethical implications are revisited. This newly described methodology can be translated to larger clinical trials, finally exerting the real effect of full correction via single vision spectacle lens wear on eye growth and myopia progression.
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http://dx.doi.org/10.3390/jcm9061975DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356996PMC
June 2020

Accommodation responses following contrast adaptation.

Vision Res 2020 05 24;170:12-17. Epub 2020 Mar 24.

Carl Zeiss Vision International GmbH, Turnstrasse 27, 73430 Aalen, Germany; Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Straße 7, 72076 Tuebingen, Germany.

The current study explored the effects of contrast adaptation on the accommodation response (AR), using low- and high-pass filtered video clips as stimuli. Ten young myopic (mean ± standard deviation: -2.91 ± 1.36D) and 10 near emmetropic subjects (-0.19 ± 0.14D) participated in the study. The AR was monitored under monocular viewing conditions using an eccentric infrared photorefractor. A 2-stage procedure was used: (1) the minimum spatial frequency content necessary to produce a proper individual AR; and (2) the AR was compared before and after adaptation to low-pass (s = -0.5), control (s = 0) and high-pass (s = +0.5) filtered videos. We found that (1) the average threshold Sinc-blur of both myopes and emmetropes necessary to evoke accommodation was (mean ± standard deviation) λ = 7.40 ± 4.05 cpd. Myopes required a higher Sinc blur (average, 10.00 ± 4.05 cpd) compared to emmetropes (average, 4.80 ± 1.60 cpd). (2) Adaptation to low-pass filtered videos increased the AR by 0.41 ± 0.33D in the myopic group and reduced it in the emmetropic group by 0.31 ± 0.25D. Adaptation to high pass-filtered videos induced similar changes in both refractive groups (an increase of 0.41 ± 0.40D and 0.46 ± 0.29D for myopes and emmetropes, respectively). Our measurements show that the human AR can be modified by spatial frequency selective contrast adaptation although these were short-term effects. The perhaps most striking finding was that adaptation to low pass filtered videos had opposite effects on the AR in emmetropes and myopes. It remains to be studied whether these differences were a consequence of myopia or a contributing factor in myopia development.
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http://dx.doi.org/10.1016/j.visres.2020.03.003DOI Listing
May 2020

A metrological approach to the analysis of choroidal thickness by optical coherence tomography 3D scans in myopia research.

Sci Rep 2019 12 30;9(1):20322. Epub 2019 Dec 30.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Tuebingen, 72076, Germany.

In myopia research, changes of choroidal thickness in response to optically induced signals serve as predictor for changes in axial length that might be correlated with myopia progression. Optical coherence tomography (OCT) provides a tool for imaging the choroid, however, with certain difficulties because of a limited visibility of the scleral-choroidal interface. Considering the previously reported effect sizes of thickness change in human myopia research, this study investigated the repeatability of automated 3D choroidal segmentation across the macular area of 6 × 6 mm. Fifteen subjects underwent nine volume scans in two OCT devices with analysis of the 95% interval of repeatability, intersubject and intrasubject variations, as well as interdevice agreement. Repeatability generally improved with increasing eccentricity from the fovea. The nasal perifoveal region exhibited the best repeatability with ±19 and ±21 μm in both OCT devices, whereas the subfovea showed a repeatability of ±57 and ±44 μm, respectively. High inter- and intrasubject variations were observed, together with a negative bias in the device agreement. Although there is still limited data on thickness changes of the nasal choroid, future studies could focus more on measuring the effect size in the nasal perifoveal area to account for metrological issues in choroidal segmentation.
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http://dx.doi.org/10.1038/s41598-019-56915-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6937308PMC
December 2019

2-D Peripheral image quality metrics with different types of multifocal contact lenses.

Sci Rep 2019 12 6;9(1):18487. Epub 2019 Dec 6.

Eberhard Karls University Tuebingen, Institute for Ophthalmic Research, Tuebingen, 72076, Germany.

To evaluate the impact of multifocal contact lens wear on the image quality metrics across the visual field in the context of eye growth and myopia control. Two-dimensional cross-correlation coefficients were estimated by comparing a reference image against the computed retinal images for every location. Retinal images were simulated based on the measured optical aberrations of the naked eye and a set of multifocal contact lenses (centre-near and centre-distance designs), and images were spatially filtered to match the resolution limit at each eccentricity. Value maps showing the reduction in the quality of the image through each optical condition were obtained by subtracting the optical image quality from the theoretical physiological limits. Results indicate that multifocal contact lenses degrade the image quality independently from their optical design, though this result depends on the type of analysis conducted. Analysis of the image quality across the visual field should not be oversimplified to a single number but split into regional and groups because it provides more insightful information and can avoid misinterpretation of the results. The decay of the image quality caused by the multifocal contacts alone, cannot explain the translation of peripheral defocus towards protection on myopia progression, and a different explanation needs to be found.
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http://dx.doi.org/10.1038/s41598-019-54783-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6898319PMC
December 2019

Agreement and Repeatability of Noncycloplegic and Cycloplegic Wavefront-based Autorefraction in Children.

Optom Vis Sci 2019 11;96(11):879-889

Department of Mathematics and Natural Sciences, University of Applied Sciences, Darmstadt, Germany.

Significance: Increasing prevalence of refractive error requires assessment of ametropia as a screening tool in children. If cycloplegia is not an option, knowledge about the increase in uncertainty for wavefront-based autorefraction is needed. The cycloplegic agent as the principal variant presents cross-reference and allows for extraction of the influence of accommodation.

Purpose: The purpose of this study was to determine the repeatability, agreement, and propensity to accommodate of cycloplegic (ARc) and noncycloplegic (ARnc) wavefront-based autorefraction (ZEISS i.Profiler plus; Carl Zeiss Vision, Aalen, Germany) in children aged 2 to 15 years.

Methods: In a clinical setting, three consecutive measurements were feasible for 145 eyes (OD) under both conditions. Data are described by spherical equivalent (M), horizontal or vertical astigmatic component (J0), and oblique astigmatic component (J45). In the case of M, the most positive value of the three measurements was chosen, whereas the mean was applied for astigmatic components.

Results: Regarding agreement, differences for ARc minus ARnc were statistically significant: for M, 0.55 (0.55 D; mean [SD]; P < .001), that is, more hyperopic in cycloplegia; for J0, -0.03 (0.11 D; P = .002); and for J45, -0.03 D (SD, 0.09 D; P < .001). Regarding repeatability, astigmatic components showed excellent repeatability: SD < 0.11 D (ARnc) and SD < 0.09 D (ARc). The repeatability of M was SD = 0.57 D with a 95% interval of 1.49 D (ARnc). Under cycloplegia, this decreased to SD = 0.17 D (ARc) with a 95% interval of 0.50 D. The mean propensity to accommodate was 0.44 D from repeated measurements; in cycloplegia, this was reduced to 0.19 D.

Conclusions: Wavefront-based refraction measurement results are highly repeatable and precise for astigmatic components. Noncycloplegic measurements of M show a systematic bias of 0.55 D. Cycloplegia reduces the propensity to accommodate by a factor of 2.4; for noncycloplegic repeated measurements, accommodation is controlled to a total interval of 1.49 D (95%). Without cycloplegia, results improve drastically when measurements are repeated.
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http://dx.doi.org/10.1097/OPX.0000000000001444DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6855388PMC
November 2019

Effect of spatial filtering on accommodation.

Vision Res 2019 11 3;164:62-68. Epub 2019 Oct 3.

Carl Zeiss Vision International GmbH, Turnstrasse 27, 73430 Aalen, Germany; Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Straße 7, 72076 Tuebingen, Germany.

The purpose of this study was to develop and test a new method that uses natural images to investigate the influence of their spatial frequency content on the accommodation response (AR). Furthermore, the minimum spatial frequency content was determined that was necessary to induce an AR. Blur of the images was manipulated digitally in the Fourier domain by filtering with a Sinc function. Fourteen young subjects participated in the experiment. A 2-step procedure was used: (1) verifying that a high amount of Sinc-blur does not evoke accommodation, (2) increasing the width of the Sinc-blur filter in logarithmic steps until an AR was evoked. AR was continuously monitored using eccentric infrared photorefraction at 60 Hz sampling rate under monocular viewing conditions. Under condition (1), Sinc-blur of λ = 1 cpd did not evoke accommodation, while under condition (2) an average (mean ± standard deviation) Sinc-blur of λ = 5.57 ± 4.67 cpd (median: 4 cpd, interquartile range: 2-7 cpd) evoked accommodation. Dividing the subjects into myopes and emmetropes revealed that the myopic group required higher amounts of λ (higher spatial frequencies) to stimulate their accommodation (mean λ = 9.33 ± 4.99 cpd, for myopes; and mean λ = 2.75 ± 0.97 cpd, for emmetropes). Our results support the notion that the AR is most effectively stimulated at mid-spatial frequencies and that myopes may require higher spatial frequencies to elicit a comparable AR.
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http://dx.doi.org/10.1016/j.visres.2019.07.005DOI Listing
November 2019

The standardized definition of high myopia.

Graefes Arch Clin Exp Ophthalmol 2019 08 15;257(8):1807-1808. Epub 2019 Jun 15.

Carl Zeiss Vision International GmbH, Technology & Innovation, Turnstraße 27, 73430, Aalen, Germany.

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http://dx.doi.org/10.1007/s00417-019-04398-9DOI Listing
August 2019

Contrast adaptation appears independent of the longitudinal chromatic aberration of the human eye.

J Opt Soc Am A Opt Image Sci Vis 2019 Apr;36(4):B77-B84

As ocular chromatic aberration was suspected to cue contrast adaptation in human vision, the purpose of this study was to investigate contrast adaptation under monochromatic light conditions. Single and complex frequency adaptation stimuli were used, and monochromatic conditions were achieved using band pass filters with short (470±2  ), medium (530±2  ), and long (630±2  ) transmission wavelengths. Post-adaptational contrast sensitivity was shown to be significantly decreased for all wavelength conditions for the single frequency stimulus. A significant difference of contrast adaptation between short and long wavelengths was found. Consistently, adaptation led to a significant decrease in contrast sensitivity for the complex frequency stimulus. To conclude, contrast adaptation under mesopic illumination occurs independently of the longitudinal chromatic aberration of the eye; it can be inferred that this mechanism can be used to distinguish between the sign of optical defocus in poly- and monochromatic light conditions.
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http://dx.doi.org/10.1364/JOSAA.36.000B77DOI Listing
April 2019

A global approach to describe retinal defocus patterns.

PLoS One 2019 2;14(4):e0213574. Epub 2019 Apr 2.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Tuebingen, Baden-Wuerttemberg, Germany.

The popularity of myopia treatments based on the peripheral defocus theory has risen. So far, little evidence has emerged around the questions which of these treatments are effective and why. In order to establish a framework that enables clinicians and researchers to acknowledge the possible interactions of different defocus patterns across the retina, different peripheral refractive errors (PRX) of subjects and different designs of optical treatments were evaluated. Dioptric defocus patterns on the retinal level have been obtained by merging the matrices of dioptric defocus maps of the visual field of different scenarios with individual peripheral refractive errors and different optical designs of multifocal contact lenses. The newly obtained matrices were statistically compared using a non-parametric test with familywise error algorithms and multi-comparison tests. Results show that asymmetric peripheral refractive error profiles (temporal or nasal positively skewed) appear to be less prone to be changed by the defocus imposition of multifocal contact lenses than those presenting symmetric patterns (relative peripheral myopia or hyperopia).
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0213574PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6445412PMC
December 2019

Growth curves of myopia-related parameters to clinically monitor the refractive development in Chinese schoolchildren.

Graefes Arch Clin Exp Ophthalmol 2019 May 23;257(5):1045-1053. Epub 2019 Mar 23.

Carl Zeiss Vision International GmbH, Technology and Innovation, Turnstraße 27, 73430, Aalen, Germany.

Purpose: To produce a clinical model for the prediction of myopia development based on the creation of percentile curves of axial length in school-aged children from Wuhan in central China.

Methods: Data of 12,554 children (6054 girls and 6500 boys) were collected and analyzed for the generation of the axial length growth curves. A second data set with 226 children and three yearly successive measurements was used to verify the predictive power of the axial length growth percentile curves. Percentile curves were calculated for both gender groups and four age groups (6, 9, 12, and 15 years). The second data set was used to verify the efficacy of identifying the refractive error of the children using the axial length curves, based on their spherical refractive error from the third visit.

Results: From 6 to 15 years of age, all percentiles showed a growth trend in axial length, except for the percentiles below the first quartile, which appear to stabilize after the age of 12 (- 0.10; 95%CI, - 0.36-0.16; P = 0.23 for girls; - 0.16; 95%CI, - 0.70-0.39; P = 0.34 for boys); however, the growth continued for the remaining 75% of cases. The second data set showed that the likelihood of suffering high myopia (spherical refractive error ≤- 5.00D) during adolescent years increased when axial length values were above the first quartile, for both genders.

Conclusions: The data from the current study provide a tool to observe the annual growth rates of axial length and can be considered as an approach to predict the refractive development at school ages.
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http://dx.doi.org/10.1007/s00417-019-04290-6DOI Listing
May 2019

IMI - Industry Guidelines and Ethical Considerations for Myopia Control Report.

Invest Ophthalmol Vis Sci 2019 02;60(3):M161-M183

Brien Holden Vision Institute, and School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.

Purpose: To discuss guidelines and ethical considerations associated with the development and prescription of treatments intended for myopia control (MC).

Methods: Critical review of published papers and guidance documents was undertaken, with a view to carefully considering the ethical standards associated with the investigation, development, registration, marketing, prescription, and use of MC treatments.

Results: The roles and responsibilities of regulatory bodies, manufacturers, academics, eye care practitioners, and patients in the use of MC treatments are explored. Particular attention is given to the ethical considerations for deciding whether to implement a MC strategy and how to implement this within a clinical trial or practice setting. Finally, the responsibilities in marketing, support, and education required to transfer required knowledge and skills to eye care practitioners and academics are discussed.

Conclusions: Undertaking MC treatment in minors creates an ethical challenge for a wide variety of stakeholders. Regulatory bodies, manufacturers, academics, and clinicians all share an ethical responsibility to ensure that the products used for MC are safe and efficacious and that patients understand the benefits and potential risks of such products. This International Myopia Institute report highlights these ethical challenges and provides stakeholders with recommendations and guidelines in the development, financial support, prescribing, and advertising of such treatments.
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http://dx.doi.org/10.1167/iovs.18-25963DOI Listing
February 2019

Comparison of two devices to simulate vision with intraocular lenses.

Clin Ophthalmol 2019 4;13:123-130. Epub 2019 Jan 4.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Tuebingen, Baden-Wuerttemberg, Germany,

Introduction: The simulation of vision with intraocular lenses (IOLs) prior to the clinical validation is of great interest for manufacturers as well as clinicians. We have tested the influence of different IOLs on the perception of contrast using different devices.

Materials And Methods: A Rassow telescope and the VirtIOL have been used to assess the contrast sensitivity function (CSF) through monfocal IOL (CT Asphina 409 MP, IOL 1), multifocal IOL (AT LISA tri 839 MP, IOL 2) and extended-depth-of-focus-IOL (TECNIS Symfony ZXR00, IOL3) in 21 participants, aged between 22 and 29 years. Contrast sensitivity (CS) was tested at various spatial frequencies (3-30 cycles per degree), using the Tuebingen contrast sensitivity test.

Results: All tested IOL reduced the CS when compared to measurements with a trial lens correction of refractive errors. The analysis of the area under the curve of the contrast sensitivity function (AUC-CSF) revealed a significant reduction compared to the trial lens correction in case the Rassow telescope was used (IOL 1: =0.008; IOL2: <0.001; IOL3: <0.001) and the same was true for the VirtIOL device for IOL2 and IOL3 (IOL2: <0.001; IOL3: <0.001), but not for IOL1 (=0.192). Interdevice analysis of the AUC-CSF revealed significant differences for IOL1 and IOL2 (IOL1: =0.025; IOL2: <0.001), while no difference was found for IOL3 (=0.092). Bland-Altman analysis as well as intraclass correlations coefficients indicated only weak interdevice agreement for the tested IOL.

Conclusion: The assessment of the interdevice analysis for the Rassow telescope and the VirtIOL device revealed only a minor agreement between the two devices. In order to investigate vision with IOLs prior to a clinical validation, the use of the VirtIOL device is recommended.
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http://dx.doi.org/10.2147/OPTH.S188890DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6324601PMC
January 2019

The effect of the optical design of multifocal contact lenses on choroidal thickness.

PLoS One 2018 16;13(11):e0207637. Epub 2018 Nov 16.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Tuebingen, Germany.

Studies have found reduced myopia progression with multifocal contact lenses, albeit with an unclear mechanism behind their protective effect. It is hypothesized that the induced myopic defocus of the addition zones of the multifocal contact lenses leads to choroidal thickening and therefore inhibits eye growth. In the current study, the effect of the optical design of multifocal contact lenses on choroidal thickness was investigated. Eighteen myopic participants wore four different contact lenses ((1) single-vision lenses corrected for distance, (2) single-vision lenses with +2.50 D full-field defocus, (3) Multifocal center-distance design, (4) Multifocal center-near design, both with addition power +2.50 D) for 30 min each on their right eye. Automated analysis of the macular choroidal thickness and vitreous chamber depth were performed before and after the wear of each of the contact lenses. Peripheral refraction profiles in primary gaze were obtained using eccentric photorefraction prior to contact lens wear. Choroidal thickness and vitreous chamber depth showed no significant differences to baseline with any of the contact lenses (all p > 0.05). Choroidal thickness increased by +2.1 ± 11.1 μm with the Multifocal center-distance design, by +2.0 ± 11.1 μm with the full-field defocus lens, followed by the Multifocal center-near design with +1.6 ± 11.3 μm and the single-vision contact lens correcting for distance with +0.9 ± 11.2 μm. Multifocal contact lenses have no significant influence on choroidal thickness after short-term wear. Therefore, changes in choroidal thickness might not be the main contributor to the protective effect of multifocal contact lenses in myopia control.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0207637PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6239323PMC
April 2019

Individual neural transfer function affects the prediction of subjective depth of focus.

Sci Rep 2018 01 30;8(1):1919. Epub 2018 Jan 30.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 7, Tuebingen, 72076, Germany.

Attempts to accurately predict the depth of focus (DoF) based on objective metrics have failed so far. We investigated the effect of the individual neural transfer function (iNTF) on the quality of the prediction of the subjective DoF from objective wavefront measures. Subjective DoF was assessed in 22 participants using subjective through focus curves of visual acuity (VA). Objective defocus curves were calculated for visual Strehl metrics of the optical (VSOTFa) and the modulation transfer function as well as the point spread function. DoF was computed for residual lower order aberrations (rLoA) and incorporation of iNTF. Correlations between subjective and objective DoF did not reach significance, when a) standard metrics were used and b) rLoA were considered (r  = 0.33, p  > 0.05). By incorporating the iNTF of the individuals in the calculation of the objective DoF from the VSOTFa metric, a moderate statistically significant correlation was found (r = 0.43, p < 0.01, Pearson). The iNTF of the individual's eye is fundamental for the prediction of subjective DoF using the VSOTFa metric. Individualized predictions could aid future application in the correction of refractive errors like presbyopia using intraocular lenses.
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http://dx.doi.org/10.1038/s41598-018-20344-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5790003PMC
January 2018

Dioptric defocus maps across the visual field for different indoor environments.

Biomed Opt Express 2018 Jan 22;9(1):347-359. Epub 2017 Dec 22.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Straße 7, Tuebingen, 72076, Germany.

One of the factors proposed to regulate the eye growth is the error signal derived from the defocus in the retina and actually, this might arise from defocus not only in the fovea but the whole visual field. Therefore, myopia could be better predicted by spatio-temporally mapping the 'environmental defocus' over the visual field. At present, no devices are available that could provide this information. A 'Kinect sensor v1' camera (Microsoft Corp.) and a portable eye tracker were used for developing a system for quantifying 'indoor defocus error signals' across the central 58° of the visual field. Dioptric differences relative to the fovea (assumed to be in focus) were recorded over the visual field and 'defocus maps' were generated for various scenes and tasks.
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http://dx.doi.org/10.1364/BOE.9.000347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5772587PMC
January 2018

Self-assessment of refractive errors using a simple optical approach.

Clin Exp Optom 2018 05 21;101(3):386-391. Epub 2018 Jan 21.

Institute for Ophthalmic Research, Eberhard Karls University of Tuebingen, Tuebingen, Germany.

Background: This explorative study investigated procedures for the self-assessment of spherocylindrical refractive errors.

Methods: Eighteen participants with a mean age of 34.0 ± 8.8 years were enrolled. Adjustable Alvarez lenses were mounted in a rotatable ring holder and two procedures were tested for the self-adjustment: (1) rotation of the lens in three meridians: 0°, 60° and 120° and (2) rotation of the optotypes in the same meridians. Starting from maximum positive power, the participants were required to decrease the power of the Alvarez lens until the optotypes (0.0 logMAR) appeared to be clear the first time. Best-corrected visual acuity (BVA) was measured using a psychophysical staircase procedure. Bland-Altmann analysis was carried out in order to calculate the limits of agreement between the self-refraction method and the standard subjective refraction.

Results: Using procedure 1, 77 per cent of the subjects achieved a VA ≥ 0.1 logMAR (6/7.5) and the same was true for 88 per cent of the subjects using procedure 2. Using procedure 1, a significantly worse BVA was found, when compared to subjective refraction (ΔVA = -0.15 logMAR, F  = 7.11, p = 0.046, median test). Analysis of variance (ANOVA) analysis showed a significant influence of the refraction method on the oblique astigmatism component J but not for the spherical equivalent M and the straight astigmatism component J (M: F  = 0.532, p = 0.661; J : F  = 0.056, p = 0.983; J : F  = 13.97, p < 0.001; ANOVA). The limits of agreement for the spherical equivalent error M were ± 1.10 D and ± 1.20 D and for the astigmatic components J ± 0.78 D and ± 0.59 D and for J ± 0.62 D and ± 0.54 D, for procedure 1 and procedure 2, respectively.

Conclusions: Fixed adjustable Alvarez lenses and rotatable stimuli can provide a fast and precise self-assessment method to measure the spherocylindrical error of the eye.
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http://dx.doi.org/10.1111/cxo.12650DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5947140PMC
May 2018

Symmetric visual response to positive and negative induced spherical defocus under monochromatic light conditions.

Vision Res 2018 02 28;143:52-57. Epub 2017 Dec 28.

Institute for Ophthalmic Research, Eberhard Karls University of Tuebingen, Germany; Technology and Innovation, Carl Zeiss Vision International GmbH, Aalen, Germany. Electronic address:

The purpose of the study was to investigate the sign-dependent response to real and simulated spherical defocus on the visual acuity under monochromatic light conditions. The investigation included 15 myopic participants with a mean spherical equivalent error of -2.98 ± 2.17 D. Visual acuity (VA) was tested with and without spherical defocus using the source method (simulated defocus) and the observer method (lens-induced defocus) in a range of ±3.0 D in 1.0 D steps. VA was assessed using Landolt C's, while the threshold was determined with an adaptive staircase procedure. Monochromatic light conditions were achieved using band pass filters with a wavelength of 450 ± 2 nm, 530 ± 2 nm and 630 ± 2 nm. Results showed that the reduction of VA was significantly different under blue lighting conditions, when compared to the green and red light conditions. No significant difference in the reduction of the VA was found between the positive and the negative sign of defocus for all lighting conditions. The agreement for the VA between the source and observer method was significantly dependent on the wavelength as well as on the level of defocus. To conclude, under monochromatic light conditions, myopes show a symmetric sign-dependency regarding the influence of spherical defocus on visual acuity. The observed results indicate that the human visual system is capable of integrating the chromatic differences in refraction to distinguish between the signs of defocus.
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http://dx.doi.org/10.1016/j.visres.2017.12.003DOI Listing
February 2018

Disability glare in soft multifocal contact lenses.

Cont Lens Anterior Eye 2018 04 7;41(2):175-179. Epub 2017 Oct 7.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Straße 7, 72076 Tuebingen, Germany; Carl Zeiss Vision International GmbH, Turnstrasse 27, 73430 Aalen, Germany.

Purpose: The study investigated the effect of the design of multifocal contact lenses on the sensitivity to contrast and disability glare.

Methods: Contrast sensitivity was measured in 16 young adults (mean age: 25.5±2.5years) at a distance of 2m under two conditions: no-glare and glare. Two designs (Center Near and Center Distance) of the Biofinity soft contact lens were used to simulate correction for presbyopes, while a correction with single vision trial lenses and contact lenses acted as controls.

Results: The design of the used multifocal contact lenses had a significant influence on the log area under the curve of the contrast sensitivity function (AUC-CSF). Compared to the spectacle lens correction, the AUC-CSF was significantly reduced, in case CS was measured with the Center Near design lens, under the no-glare (p<0.001) and the glare condition (p: p<0.001). In case of the Center Distance design contact lens, the AUC-CSF was significantly smaller in case CS was tested under glare (p=0.001). Disability glare (DG) was depending on the spatial frequency and the design of the multifocal lens, while the Center Distance design produced higher amounts of DG (p<0.001), compared to the other used corrections.

Conclusion: The optical design of a multifocal contact lenses has a significant impact on the contrast sensitivity as well as the disability glare. In order to dispense the best correction in terms of contact lenses, the sensitivity to contrast under no-glare and glare conditions should be tested a medium spatial frequencies.
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http://dx.doi.org/10.1016/j.clae.2017.10.002DOI Listing
April 2018

Peripheral Design of Progressive Addition Lenses and the Lag of Accommodation in Myopes.

Invest Ophthalmol Vis Sci 2017 07;58(9):3319-3324

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Tuebingen, Germany 2Carl Zeiss Vision International GmbH, Aalen, Germany.

Purpose: Insufficient accommodative response is assumed to result in myopia progression. We have investigated if the accommodative lag in myopes is different between a single vision lens (SVL) and the progressive addition lens PAL 2, clinically trialled for its ability to reduce progression of myopia, and if there exist differences in accommodative lag between PAL 2 and other PALs with the same addition power (+1.50 D).

Methods: The influence of spherical SVL and four different designs of PALs that differ in the near zone width (PAL 1) or that have different signs and magnitude of horizontal gradients of mean power adjacent to their near vision zones (PAL 3 and PAL 4) on the accommodative response was investigated for different near viewing distances (40, 33, and 25 cm) in 31 subjects, aged 18 to 25 years.

Results: The SVL correction resulted in insufficient accommodative response for the near object viewing distances tested. PAL 2 did significantly reduce accommodative lag for all near object distances tested. The PAL design with a more negative horizontal mean power gradient (PAL 4) provided a lower lag of accommodation when compared with PAL 2 at the shortest object distance of 25 cm (P = 0.03) and was able to reduce the lag of accommodation to a level below the depth of focus for the higher near working distances tested.

Conclusions: Designs of PAL with more negative horizontal mean power gradients are the most effective in lowering the lag of accommodation in myopes. This could make them good test candidates for myopia control applications.
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http://dx.doi.org/10.1167/iovs.17-21589DOI Listing
July 2017

TuebingenCSTest - a useful method to assess the contrast sensitivity function.

Biomed Opt Express 2017 Mar 10;8(3):1477-1487. Epub 2017 Feb 10.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Straße 7, 72076 Tuebingen, Germany.

Since contrast sensitivity (CS) relies on the accuracy of stimulus presentation, the reliability of the psychophysical procedure and observer's attention, the measurement of the CS-function is critical and therefore, a useful threshold contrast measurement was developed. The Tuebingen Contrast Sensitivity Test (TueCST) includes an adaptive staircase procedure and a 16-bit gray-level resolution. In order to validate the CS measurements with the TueCST, measurements were compared with existing tests by inter-test repeatability, test-retest reliability and time. The novel design enables an accurate presentation of the spatial frequency and higher precision, inter-test repeatability and test-retest reliability compared to other existing tests.
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http://dx.doi.org/10.1364/BOE.8.001477DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5480558PMC
March 2017

Reducing the lag of accommodation by auditory biofeedback: A pilot study.

Vision Res 2016 12 1;129:50-60. Epub 2016 Nov 1.

Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Straße 7, 72076 Tuebingen, Germany; Carl Zeiss Vision International GmbH, Turnstrasse 27, 73430 Aalen, Germany.

The purpose of this study was to investigate whether a reduction of the accommodative lag is possible by training the accuracy of accommodation using auditory biofeedback. Accommodation responses were measured in thirty-one young adults with myopia for dioptric target distances of 2.0, 2.5, and 3.0D using an eccentric infrared photorefractor. For the biofeedback training, subjects were randomly assigned to an experimental (n=15) or a control group (n=16). Subjects of the experimental group were provided with two tones while fixating a target, one tone was related to their accommodative response and the second to the target distance. Their task was to match these tones. The control group did not receive any auditory biofeedback. Two different training methods were applied, a continuous training of 200s, and ten consecutive sessions of 20s each. The training effects on the lag of accommodation (change Δ) were highly variable. Regarding the entire study group, the observed change in the accommodative lag was greater at closer distances, while no difference between the two training methods was revealed. Nevertheless, seven experimental subjects reduced their lag by ⩾0.3D (3.0D target distance: Δ=-0.29±0.20D, Δ=-0.24±0.21D). This reduction was also seen in two control subjects. Remeasurement revealed that the average training effect cannot be preserved over a period of 5-7days. The current investigation has shown that the accuracy of accommodation can be trained in some subjects using auditory biofeedback for target distances of 2.5D or closer.
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http://dx.doi.org/10.1016/j.visres.2016.10.002DOI Listing
December 2016

The Influence of Induced Astigmatism on the Depth of Focus.

Optom Vis Sci 2016 10;93(10):1228-34

*MSc †PhD ZEISS Vision Science Lab, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany (all authors).

Purpose: To evaluate whether an induced astigmatism influences the subjective depth of focus.

Methods: Fifty-one participants aged 18 to 35 years and with a mean spherical equivalent refractive error of -0.51 ± 2.35 DS participated in the study. The accommodation was blocked with three drops of 1% cyclopentolate. Refractive errors were corrected after subjective refraction with a 4-mm artificial pupil. To evaluate the depth of focus (DoF), defocus curves with a spherical range of ±1.5 DS were assessed. The DoF was calculated as the horizontal distance at a threshold level of +0.1 logMAR from the maximum visual acuity (VA). Defocus curves were estimated binocularly during distance (500 cm) and a near vision (40 cm) for two induced axis (ATR in 0° and WTR in 90°) and for a fixed amount of astigmatic defocus of -0.5 DC.

Results: The mean natural DoF was 0.885 ± 0.316 D for far vision and 0.940 ± 0.400 D for near vision. With induced astigmatism, the DoF for far vision was significantly increased to 1.095 ± 0.421 D (p = 0.006, ANOVA) for the WTR astigmatism but not for the ATR astigmatism (1.030 ± 0.395 D; p = 0.164, ANOVA). The induced WTR astigmatism enhanced the DoF for near vision significantly to 1.144 ± 0.338 D (p = 0.04, ANOVA), and DoF with induced ATR astigmatism (0.953 ± 0.318 D) was not significantly different (p = 1.00, ANOVA). ATR-astigmatism reduced VA by +0.08 ± 0.08 logMAR (p < 0.01, t-test).

Conclusions: With an induced WTR astigmatism of -0.5 DC, the DoF can be enhanced in the near viewing distance with a marginal loss in binocular VA. The approach of using induced WTR astigmatism can lead to novel optical treatments for presbyopia.
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http://dx.doi.org/10.1097/OPX.0000000000000961DOI Listing
October 2016

Steps towards Smarter Solutions in Optometry and Ophthalmology-Inter-Device Agreement of Subjective Methods to Assess the Refractive Errors of the Eye.

Healthcare (Basel) 2016 Jul 13;4(3). Epub 2016 Jul 13.

Institute for Ophthalmic Research, University of Tuebingen, Geschwister-Scholl-Platz, 72074 Tübingen, Germany.

Purpose: To investigate the inter-device agreement and mean differences between a newly developed digital phoropter and the two standard methods (trial frame and manual phoropter).

Methods: Refractive errors of two groups of participants were measured by two examiners (examiner 1 (E1): 36 subjects; examiner 2 (E2): 38 subjects). Refractive errors were assessed using a trial frame, a manual phoropter and a digital phoropter. Inter-device agreement regarding the measurement of refractive errors was analyzed for differences in terms of the power vector components (spherical equivalent (SE) and the cylindrical power vector components J0 and J45) between the used methods. Intraclass correlation coefficients (ICC's) were calculated to evaluate correlations between the used methods.

Results: Analyzing the variances between the three methods for SE, J0 and J45 using a two-way ANOVA showed no significant differences between the methods (SE: p = 0.13, J0: p = 0.58 and J45: p = 0.96) for examiner 1 and for examiner 2 (SE: p = 0.88, J0: p = 0.95 and J45: p = 1). Mean differences and ±95% Limits of Agreement for each pair of inter-device agreement regarding the SE for both examiners were as follows: Trial frame vs. digital phoropter: +0.10 D ± 0.56 D (E1) and +0.19 D ± 0.60 D (E2), manual phoropter vs. trial frame: -0.04 D ± 0.59 D (E1) and -0.12 D ± 0.49 D (E2) and for manual vs. digital phoropter: +0.06 D ± 0.65 D (E1) and +0.08 D ± 0.45 D (E2). ICCs revealed high correlations between all methods for both examiner (p < 0.001). The time to assess the subjective refraction was significantly smaller with the digital phoropter (examiner 1: p < 0.001; examiner 2: p < 0.001).

Conclusion: "All used subjective methods show a good agreement between each other terms of ICC (>0.9). Assessing refractive errors using different subjective methods, results in similar mean differences and 95% limits of agreement, when compared to those reported in studies comparing subjective refraction non-cylcoplegic retinoscopy or autorefraction".
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5041042PMC
http://dx.doi.org/10.3390/healthcare4030041DOI Listing
July 2016

Comparison of progressive addition lenses for general purpose and for computer vision: an office field study.

Clin Exp Optom 2015 May;98(3):234-43

Technology & Innovation, Carl Zeiss Vision GmbH, Aalen, Germany.

Background: Two types of progressive addition lenses (PALs) were compared in an office field study: 1. General purpose PALs with continuous clear vision between infinity and near reading distances and 2. Computer vision PALs with a wider zone of clear vision at the monitor and in near vision but no clear distance vision.

Methods: Twenty-three presbyopic participants wore each type of lens for two weeks in a double-masked four-week quasi-experimental procedure that included an adaptation phase (Weeks 1 and 2) and a test phase (Weeks 3 and 4). Questionnaires on visual and musculoskeletal conditions as well as preferences regarding the type of lenses were administered. After eight more weeks of free use of the spectacles, the preferences were assessed again. The ergonomic conditions were analysed from photographs.

Results: Head inclination when looking at the monitor was significantly lower by 2.3 degrees with the computer vision PALs than with the general purpose PALs. Vision at the monitor was judged significantly better with computer PALs, while distance vision was judged better with general purpose PALs; however, the reported advantage of computer vision PALs differed in extent between participants. Accordingly, 61 per cent of the participants preferred the computer vision PALs, when asked without information about lens design. After full information about lens characteristics and additional eight weeks of free spectacle use, 44 per cent preferred the computer vision PALs.

Conclusion: On average, computer vision PALs were rated significantly better with respect to vision at the monitor during the experimental part of the study. In the final forced-choice ratings, approximately half of the participants preferred either the computer vision PAL or the general purpose PAL. Individual factors seem to play a role in this preference and in the rated advantage of computer vision PALs.
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http://dx.doi.org/10.1111/cxo.12259DOI Listing
May 2015

Computer vision syndrome in presbyopia and beginning presbyopia: effects of spectacle lens type.

Clin Exp Optom 2015 May;98(3):228-33

Technology and Innovation, Carl Zeiss Vision GmbH, Aalen, Germany.

Purpose: This office field study investigated the effects of different types of spectacle lenses habitually worn by computer users with presbyopia and in the beginning stages of presbyopia. Computer vision syndrome was assessed through reported complaints and ergonomic conditions.

Methods: A questionnaire regarding the type of habitually worn near-vision lenses at the workplace, visual conditions and the levels of different types of complaints was administered to 175 participants aged 35 years and older (mean ± SD: 52.0 ± 6.7 years). Statistical factor analysis identified five specific aspects of the complaints. Workplace conditions were analysed based on photographs taken in typical working conditions.

Results: In the subgroup of 25 users between the ages of 36 and 57 years (mean 44 ± 5 years), who wore distance-vision lenses and performed more demanding occupational tasks, the reported extents of 'ocular strain', 'musculoskeletal strain' and 'headache' increased with the daily duration of computer work and explained up to 44 per cent of the variance (rs = 0.66). In the other subgroups, this effect was smaller, while in the complete sample (n = 175), this correlation was approximately rs = 0.2. The subgroup of 85 general-purpose progressive lens users (mean age 54 years) adopted head inclinations that were approximately seven degrees more elevated than those of the subgroups with single vision lenses.

Conclusions: The present questionnaire was able to assess the complaints of computer users depending on the type of spectacle lenses worn. A missing near-vision addition among participants in the early stages of presbyopia was identified as a risk factor for complaints among those with longer daily durations of demanding computer work.
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http://dx.doi.org/10.1111/cxo.12248DOI Listing
May 2015

Lack of oblique astigmatism in the chicken eye.

Vision Res 2015 Apr 18;109(Pt A):68-76. Epub 2015 Feb 18.

Section of Neurobiology of the Eye, Ophthalmic Research Institute, Calwerstraße 7/1, 72076 Tübingen, Germany. Electronic address:

Primate eyes display considerable oblique off-axis astigmatism which could provide information on the sign of defocus that is needed for emmetropization. The pattern of peripheral astigmatism is not known in the chicken eye, a common model of myopia. Peripheral astigmatism was mapped out over the horizontal visual field in three chickens, 43 days old, and in three near emmetropic human subjects, average age 34.7years, using infrared photoretinoscopy. There were no differences in astigmatism between humans and chickens in the central visual field (chicks -0.35D, humans -0.65D, n.s.) but large differences in the periphery (i.e. astigmatism at 40° in the temporal visual field: humans -4.21D, chicks -0.63D, p<0.001, unpaired t-test). The lack of peripheral astigmatism in chicks was not due to differences in corneal shape. Perhaps related to their superior peripheral optics, we found that chickens had excellent visual performance also in the far periphery. Using an automated optokinetic nystagmus paradigm, no difference was observed in spatial visual performance with vision restricted to either the central 67° of the visual field or to the periphery beyond 67°. Accommodation was elicited by stimuli presented far out in the visual field. Transscleral images of single infrared LEDs showed no sign of peripheral astigmatism. The chick may be the first terrestrial vertebrate described to lack oblique astigmatism. Since corneal shape cannot account for the difference in astigmatism in humans and chicks, it must trace back to the design of the crystalline lens. The lack of peripheral astigmatism in chicks also excludes a role in emmetropization.
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http://dx.doi.org/10.1016/j.visres.2015.02.002DOI Listing
April 2015
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