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Boszczyk A, Dębowy F, Jóźwik A, Dahaghin A, Siedlecki D. Complexity of crystalline lens wobbling investigated by means of combined mechanical and optical simulations. BIOMEDICAL OPTICS EXPRESS 2023; 14:2465-2477. [PMID: 37342700 PMCID: PMC10278604 DOI: 10.1364/boe.488176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 04/14/2023] [Accepted: 04/15/2023] [Indexed: 06/23/2023]
Abstract
Crystalline lens wobbling is a phenomenon when the lens oscillates briefly from its normal position immediately after stopping the rotational movement of the eye globe. It can be observed by means of Purkinje imaging. The aim of this research is to present the data and computation workflow that involve both biomechanical and optical simulations that can mimic this effect, aimed to better understanding of lens wobbling. The methodology described in the study allows to visualize both the dynamic changes of the lens conformation within the eye and its optical effect in terms of Purkinje performance.
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Affiliation(s)
- Agnieszka Boszczyk
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-340 Wroclaw, Poland
| | - Fabian Dębowy
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-340 Wroclaw, Poland
- Currently with the Medical Technology Research Centre, Faculty of Health, Education, Medicine and Social Care, Chelmsford Campus, Bishops Hall Lane, Chelmsford CM1 1SQ, UK
| | - Agnieszka Jóźwik
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-340 Wroclaw, Poland
| | - Ali Dahaghin
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-340 Wroclaw, Poland
| | - Damian Siedlecki
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-340 Wroclaw, Poland
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Bowers NR, Gautier J, Lin S, Roorda A. Fixational eye movements in passive versus active sustained fixation tasks. J Vis 2021; 21:16. [PMID: 34677574 PMCID: PMC8556553 DOI: 10.1167/jov.21.11.16] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Human fixational eye movements are so small and precise that high-speed, accurate tools are needed to fully reveal their properties and functional roles. Where the fixated image lands on the retina and how it moves for different levels of visually demanding tasks is the subject of the current study. An Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO) was used to image, track and present a variety of fixation targets (Maltese cross, disk, concentric circles, Vernier and tumbling-E letter) to healthy subjects. During these different passive (static) or active (discriminating) tasks under natural eye motion, the landing position of the target on the retina was tracked in space and time over the retinal image directly with high spatial (<1 arcmin) and temporal (960 Hz) resolution. We computed both the eye motion and the exact trajectory of the fixated target's motion over the retina. We confirmed that compared to passive tasks, active tasks elicited a partial inhibition of microsaccades, leading to longer drift periods compensated by larger corrective saccades. Consequently, the overall fixation stability during active tasks was on average 57% larger than during passive tasks. The preferred retinal locus of fixation was the same for each task and did not coincide with the location of the peak cone density.
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Affiliation(s)
- Norick R Bowers
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA, USA.,
| | - Josselin Gautier
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA, USA.,
| | - Samantha Lin
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA, USA.,
| | - Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA, USA.,
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Abstract
The study of fixational eye motion has implications for the neural and computational underpinnings of vision. One component of fixational eye motion is tremor, a high-frequency oscillatory jitter reported to be anywhere from ∼11-60 arcseconds in amplitude. In order to isolate the effects of tremor on the retinal image directly and in the absence of optical blur, high-frequency, high-resolution eye traces were collected in six subjects from videos recorded with an adaptive optics scanning laser ophthalmoscope. Videos were acquired while subjects engaged in an active fixation task where they fixated on a tumbling E stimulus and reported changes in its orientation. Spectral analysis was conducted on periods of ocular drift, with all drifts being concatenated together after removal of saccades from the trace. The resultant amplitude spectra showed a slight deviation from the traditional 1/f nature of optical drift in the frequency range of 50-100 Hz, which is indicative of tremor. However, this deviation rarely exceeded 1 arcsecond and the consequent standard deviation of retinal image motion over the tremor band (50-100 Hz) was just over 5 arcseconds. Given such a small amplitude, it is unlikely tremor will contribute in any meaningful way to the visual percept.
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Affiliation(s)
- Norick R Bowers
- School of Optometry and Vision Science Graduate Group, University of California-Berkeley, Berkeley, CA, USA
| | - Alexandra E Boehm
- School of Optometry and Vision Science Graduate Group, University of California-Berkeley, Berkeley, CA, USA
| | - Austin Roorda
- School of Optometry and Vision Science Graduate Group, University of California-Berkeley, Berkeley, CA, USA
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Yamagishi S, Yoneya M, Furukawa S. Relationship of postsaccadic oscillation with the state of the pupil inside the iris and with cognitive processing. J Neurophysiol 2020; 123:484-495. [PMID: 31825707 PMCID: PMC7052648 DOI: 10.1152/jn.00205.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Recent studies using video-based eye tracking have presented accumulating evidence that postsaccadic oscillation defined in reference to the pupil center (PSOp) is larger than that to the iris center (PSOi). This indicates that the relative motion of the pupil reflects the viscoelasticity of the tissue of the iris. It is known that the pupil size controlled by the sphincter/dilator pupillae muscles reflects many aspects of cognition. A hypothesis derived from this fact is that cognitive tasks affect the properties of PSOp due to the change in the state of these muscles. To test this hypothesis, we conducted pro- and antisaccade tasks for human participants and adopted the recent physical model of PSO to evaluate the dynamic properties of PSOp/PSOi. The results showed the dependence of the elasticity coefficient of the PSOp on the antisaccade task, but this effect was not significant for the PSOi. This suggests that cognitive tasks such as antisaccade tasks affect elasticity of the muscle of the iris. We found that the trial-by-trial fluctuation in the presaccade absolute pupil size correlated with the elasticity coefficient of PSOp. We also found the task dependence of the viscosity coefficient and overshoot amount of PSOi, which probably reflects the dynamics of the entire eyeball movement. The difference in task dependence between PSOp and PSOi indicates that the separate measures of these two can be means to distinguish factors related to the oculomotor neural system from those related to the physiological states of the iris tissue. NEW & NOTEWORTHY The state of the eyeball varies dynamically moment by moment depending on underlying neural/cognitive processing. Combining simultaneous measurements of pupil-centric and iris-centric movements and a recent physical model of postsaccadic oscillation (PSO), we show that the pupil-centric PSO is sensitive to the type of saccade task, suggesting that the physical state of the iris muscles reflects the underlying cognitive processes.
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Affiliation(s)
| | - Makoto Yoneya
- NTT Communication Science Laboratories, Kanagawa, Japan
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Abstract
Small saccades, known as microsaccades, occur frequently during fixation. Several recent studies have argued that a considerable fraction of these movements are present in the traces from one eye only. This claim contrasts with the findings of older reports, which concluded that microsaccades, like larger saccades, are virtually always binocular events. Here we examined the characteristics of small saccades by means of two of the most established high-resolution eye-tracking techniques available. A binocular Dual Purkinje Image eye-tracker was used to record eye movements while observers fixated, with their head immobilized, on markers displayed on a monitor. A specially designed eye-coil system was used to measure eye movements during normal head-free viewing, while subjects fixated on markers at various distances. Monocular microsaccades were virtually absent in both datasets. In the head-fixed data, not a single monocular microsaccade was observed. In the head-free data, only one event appeared to be monocular out of more than a thousand saccades. Monocular microsaccades do not seem to occur during normal head-free or head-immobilized fixation.
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Affiliation(s)
- Yu Fang
- Department of Psychological & Brain Sciences, Boston University, Boston, MA, USA
| | - Christopher Gill
- Department of Psychological & Brain Sciences, Boston University, Boston, MA, USA
| | - Martina Poletti
- Department of Neuroscience, University of Rochester, Rochester, NY, USA.,Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Michele Rucci
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA
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Effect of Cycloplegia on Keratometric and Biometric Parameters in Keratoconus. J Ophthalmol 2017; 2016:3437125. [PMID: 28058115 PMCID: PMC5183766 DOI: 10.1155/2016/3437125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 10/30/2016] [Accepted: 11/16/2016] [Indexed: 12/26/2022] Open
Abstract
Purpose. To obtain information about effect of cycloplegia on keratometry and biometry in keratoconus. Methods. 48 keratoconus (Group 1) and 52 healthy subjects (Group 2) were included in the study. We measured the flat meridian of the anterior corneal surface (K1), steep meridian of the anterior corneal surface (K2), lens thickness (LT), anterior chamber depth (ACD), and axial length (AL) using the Lenstar LS 900 before and after cycloplegia. Results. The median K1 in Group 1 was 45.64 D before and 45.42 D after cycloplegia, and the difference was statistically significant (P < 0.05). The median K2 in Group 1 was 50.96 D before and 50.17 D after cycloplegia, and the difference was significant (P < 0.05). The median K1 and K2 in Group 2 were 42.84 and 44.49 D, respectively, before cycloplegia, and 42.84 and 44.56 D after cycloplegia, and the differences were not statistically significant (all P > 0.05). There were significant differences in SE, LT, ACD, and RLP between before and after cycloplegia in either Group 1 (all P < 0.05) or Group 2 (all P < 0.05). There were not statistically significant differences in AL between before cycloplegia and after cycloplegia in either Group 1 (P = 0.533) or group 2 (P = 0.529). Conclusions. Flattened corneal curvature and increase in ACD following cycloplegia in keratoconus patients were detected.
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The accommodative ciliary muscle function is preserved in older humans. Sci Rep 2016; 6:25551. [PMID: 27151778 PMCID: PMC4858807 DOI: 10.1038/srep25551] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 04/19/2016] [Indexed: 11/09/2022] Open
Abstract
Presbyopia, the loss of the eye's accommodation capability, affects all humans aged above 45-50 years old. The two main reasons for this to happen are a hardening of the crystalline lens and a reduction of the ciliary muscle functionality with age. While there seems to be at least some partial accommodating functionality of the ciliary muscle at early presbyopic ages, it is not yet clear whether the muscle is still active at more advanced ages. Previous techniques used to visualize the accommodation mechanism of the ciliary muscle are complicated to apply in the older subjects, as they typically require fixation stability during long measurement times and/or to have an ultrasound probe directly in contact with the eye. Instead, we used our own developed method based on high-speed recording of lens wobbling to study the ciliary muscle activity in a small group of pseudophakic subjects (around 80 years old). There was a significant activity of the muscle, clearly able to contract under binocular stimulation of accommodation. This supports a purely lenticular-based theory of presbyopia and it might stimulate the search for new solutions to presbyopia by making use of the remaining contraction force still presented in the aging eye.
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Pupil size influences the eye-tracker signal during saccades. Vision Res 2016; 121:95-103. [PMID: 26940030 DOI: 10.1016/j.visres.2016.01.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 11/23/2022]
Abstract
While it is known that scleral search coils-measuring the rotation of the eye globe--and modern, video based eye trackers-tracking the center of the pupil and the corneal reflection (CR)--produce signals with different properties, the mechanisms behind the differences are less investigated. We measure how the size of the pupil affects the eye-tracker signal recorded during saccades with a common pupil-CR eye-tracker. Eye movements were collected from four healthy participants and one person with an aphakic eye while performing self-paced, horizontal saccades at different levels of screen luminance and hence pupil size. Results show that pupil-, and gaze-signals, but not the CR-signal, are affected by the size of the pupil; changes in saccade peak velocities in the gaze signal of more than 30% were found. It is important to be aware of this pupil size dependent change when comparing fine grained oculomotor behavior across participants and conditions.
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Ramasubramanian V, Glasser A. Prediction of accommodative optical response in prepresbyopic subjects using ultrasound biomicroscopy. J Cataract Refract Surg 2015; 41:964-80. [PMID: 26049831 DOI: 10.1016/j.jcrs.2014.12.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 11/25/2014] [Accepted: 12/14/2014] [Indexed: 10/23/2022]
Abstract
PURPOSE To determine whether relatively low-resolution ultrasound biomicroscopy (UBM) can be used to predict the accommodative optical response in prepresbyopic eyes as well as in a previous study of young phakic subjects, despite lower accommodative amplitudes. SETTING College of Optometry, University of Houston, Houston, USA. DESIGN Observational cross-sectional study. METHODS Static accommodative optical response was measured with infrared photorefraction and an autorefractor (WR-5100K) in subjects aged 36 to 46 years. A 35 MHz UBM device (Vumax, Sonomed Escalon) was used to image the left eye, while the right eye viewed accommodative stimuli. Custom-developed Matlab image-analysis software was used to perform automated analysis of UBM images to measure the ocular biometry parameters. The accommodative optical response was predicted from biometry parameters using linear regression, 95% confidence intervals (CIs), and 95% prediction intervals. RESULTS The study evaluated 25 subjects. Per-diopter (D) accommodative changes in anterior chamber depth (ACD), lens thickness, anterior and posterior lens radii of curvature, and anterior segment length were similar to previous values from young subjects. The standard deviations (SDs) of accommodative optical response predicted from linear regressions for UBM-measured biometry parameters were ACD, 0.15 D; lens thickness, 0.25 D; anterior lens radii of curvature, 0.09 D; posterior lens radii of curvature, 0.37 D; and anterior segment length, 0.42 D. CONCLUSIONS Ultrasound biomicroscopy parameters can, on average, predict accommodative optical responses with SDs of less than 0.55 D using linear regressions and 95% CIs. Ultrasound biomicroscopy can be used to visualize and quantify accommodative biometric changes and predict accommodative optical response in prepresbyopic eyes.
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Affiliation(s)
| | - Adrian Glasser
- From the College of Optometry, University of Houston, Houston, Texas, USA.
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Stevenson SB, Sheehy CK, Roorda A. Binocular eye tracking with the Tracking Scanning Laser Ophthalmoscope. Vision Res 2015; 118:98-104. [PMID: 25676884 DOI: 10.1016/j.visres.2015.01.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 12/30/2014] [Accepted: 01/07/2015] [Indexed: 11/17/2022]
Abstract
The development of high magnification retinal imaging has brought with it the ability to track eye motion with a precision of less than an arc minute. Previously these systems have provided only monocular records. Here we describe a modification to the Tracking Scanning Laser Ophthalmoscope (Sheehy et al., 2012) that splits the optical path in a way that slows the left and right retinas to be scanned almost simultaneously by a single system. A mirror placed at a retinal conjugate point redirects half of each horizontal scan line to the fellow eye. The collected video is a split image with left and right retinas appearing side by side in each frame. Analysis of the retinal motion in the recorded video provides an eye movement trace with very high temporal and spatial resolution. Results are presented from scans of subjects with normal ocular motility that fixated steadily on a green laser dot. The retinas were scanned at 4° eccentricity with a 2° square field. Eye position was extracted offline from recorded videos with an FFT based image analysis program written in Matlab. The noise level of the tracking was estimated to range from 0.25 to 0.5arcmin SD for three subjects. In the binocular recordings, the left eye/right eye difference was 1-2arcmin SD for vertical motion and 10-15arcmin SD for horizontal motion, in agreement with published values from other tracking techniques.
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Affiliation(s)
- S B Stevenson
- University of Houston College of Optometry, Berkeley School of Optometry, USA; University of California, Berkeley School of Optometry, USA.
| | - C K Sheehy
- University of Houston College of Optometry, Berkeley School of Optometry, USA; University of California, Berkeley School of Optometry, USA
| | - A Roorda
- University of Houston College of Optometry, Berkeley School of Optometry, USA; University of California, Berkeley School of Optometry, USA
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Nyström M, Andersson R, Magnusson M, Pansell T, Hooge I. The influence of crystalline lens accommodation on post-saccadic oscillations in pupil-based eye trackers. Vision Res 2015; 107:1-14. [DOI: 10.1016/j.visres.2014.10.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/13/2014] [Accepted: 10/16/2014] [Indexed: 10/24/2022]
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Tabernero J, Artal P. Lens oscillations in the human eye. Implications for post-saccadic suppression of vision. PLoS One 2014; 9:e95764. [PMID: 24755771 PMCID: PMC3995773 DOI: 10.1371/journal.pone.0095764] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/30/2014] [Indexed: 11/18/2022] Open
Abstract
The eye changes gaze continuously from one visual stimulus to another. Using a high speed camera to record eye and lens movements we demonstrate how the crystalline lens sustains an inertial oscillatory decay movement immediately after every change of gaze. This behavior fit precisely with the movement of a classical damped harmonic oscillator. The time course of the oscillations range from 50 to 60 msec with an oscillation frequency of around 20 Hz. That has dramatic implications on the image quality at the retina on the very short times (∼50 msec) that follow the movement. However, it is well known that our vision is nearly suppressed on those periods (post-saccadic suppression). Both phenomenon follow similar time courses and therefore might be synchronized to avoid the visual impairment.
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Affiliation(s)
- Juan Tabernero
- Laboratorio de Óptica, Instituto Universitario de investigación en Óptica y Nanofísica, Universidad de Murcia, Murcia, Spain
| | - Pablo Artal
- Laboratorio de Óptica, Instituto Universitario de investigación en Óptica y Nanofísica, Universidad de Murcia, Murcia, Spain
- * E-mail:
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Kook D, Kampik A, Dexl AK, Zimmermann N, Glasser A, Baumeister M, Kohnen T. Advances in lens implant technology. F1000 MEDICINE REPORTS 2013; 5:3. [PMID: 23413369 PMCID: PMC3564471 DOI: 10.3410/m5-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cataract surgery is one of the oldest and the most frequent outpatient clinic operations in medicine performed worldwide. The clouded human crystalline lens is replaced by an artificial intraocular lens implanted into the capsular bag. During the last six decades, cataract surgery has undergone rapid development from a traumatic, manual surgical procedure with implantation of a simple lens to a minimally invasive intervention increasingly assisted by high technology and a broad variety of implants customized for each patient’s individual requirements. This review discusses the major advances in this field and focuses on the main challenge remaining – the treatment of presbyopia. The demand for correction of presbyopia is increasing, reflecting the global growth of the ageing population. Pearls and pitfalls of currently applied methods to correct presbyopia and different approaches under investigation, both in lens implant technology and in surgical technology, are discussed.
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Affiliation(s)
- Daniel Kook
- Department of Ophthalmology, Ludwig Maximilians University Munich Germany
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Abstract
Presbyopia, the gradual loss of accommodation that becomes clinically significant during the fifth decade of life, is a physiologic inevitability. Different technologies are being pursued to achieve surgical correction of this disability; however, a number of limitations have prevented widespread acceptance of surgical presbyopia correction, such as optical and visual distortion, induced corneal ectasia, haze, anisometropy with monovision, regression of effect, decline in uncorrected distance vision, and the inherent risks with invasive techniques, limiting the development of an ideal solution. The correction of the presbyopia and the restoration of accommodation are considered the final frontier of refractive surgery. The purpose of this paper is to provide an update about current procedures available for presbyopia correction, their advantages, and disadvantages.
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Affiliation(s)
- André Am Torricelli
- Division of Ophthalmology, University of São Paulo Medical School, São Paulo, Brazil
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He L, Applegate RA. Predicting crystalline lens fall caused by accommodation from changes in wavefront error. J Cataract Refract Surg 2011; 37:1313-22. [PMID: 21700108 DOI: 10.1016/j.jcrs.2010.12.061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 12/16/2010] [Accepted: 12/18/2010] [Indexed: 11/15/2022]
Abstract
PURPOSE To illustrate and develop a method for estimating crystalline lens decentration as a function of accommodative response using changes in wavefront error and show the method and limitations using previously published data (2004) from 2 iridectomized monkey eyes so that clinicians understand how spherical aberration can induce coma, in particular in intraocular lens surgery. SETTINGS College of Optometry, University of Houston, Houston, USA. DESIGN Evaluation of diagnostic test or technology. METHODS Lens decentration was estimated by displacing downward the wavefront error of the lens with respect to the limiting aperture (7.0 mm) and ocular first surface wavefront error for each accommodative response (0.00 to 11.00 diopters) until measured values of vertical coma matched previously published experimental data (2007). Lens decentration was also calculated using an approximation formula that only included spherical aberration and vertical coma. RESULTS The change in calculated vertical coma was consistent with downward lens decentration. Calculated downward lens decentration peaked at approximately 0.48 mm of vertical decentration in the right eye and approximately 0.31 mm of decentration in the left eye using all Zernike modes through the 7th radial order. Calculated lens decentration using only coma and spherical aberration formulas was peaked at approximately 0.45 mm in the right eye and approximately 0.23 mm in the left eye. CONCLUSIONS Lens fall as a function of accommodation was quantified noninvasively using changes in vertical coma driven principally by the accommodation-induced changes in spherical aberration. The newly developed method was valid for a large pupil only. FINANCIAL DISCLOSURE Neither author has a financial or proprietary interest in any material or method mentioned.
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Affiliation(s)
- Lin He
- Visual Optics Institute, College of Optometry, University of Houston, Houston, Texas, USA.
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Steinbach MJ. Cyclops. Can J Ophthalmol 2010. [DOI: 10.1016/s0008-4182(10)80130-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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