Visual Psychophysics / Physiological Optics - ARVO

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ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group – Visual Psychophysics / Physiological Opticsincreasing its value in steps of 0.02 µm until the letter could not beread.Results: The threshold value for negative SA was the smallest (-0.16±0.04 µm at 5mm pupil), followed by positive SA (0.25±0.05µm). The custom threshold for VC was consistently the highest(0.78±0.12 µms), ranging from 0.70 to 0.98 µms.Monocular through focus VA was measured, both for the baselineaberration level and after inducing the individual threshold for coma.In this case, VA for the best focus position decreased by0.16LogMAR with respect to the baseline, reaching an averageabsolute VA of 0.04± 0.04LogMAR. VA decreased linearly as afunction of defocus in both cases, but has a flatter slope when theindividual threshold for VC was induced (0.17LogMAR per diopterof defocus versus 0.40LogMAR, respectively).Conclusions: Customized aberration thresholds for individualZernike modes were similar for the aberrations studied for allsubjects. The high contrast VA threshold for positive VC wasconsistently higher than that for SA demonstrating the robustness ofour visual system to this aberration and indicating that disturbancesresulting in VC, such as decentration of optical surfaces that correctspherical aberration, may play a less impact on vision than originallybelieved. The induction of VC may be advantageous for extendingdepth of focus.Commercial Relationships: Carmen Canovas, AMO GroningenB.V. (E); Patricia A. Piers, Abbott Medical Optics (E); SilvestreManzanera, AMO (F), CIBA Vision (F), CALHOUN (F),VOPTICA (I); Christina Schwarz, AMO (F); Pedro M. Prieto,AMO (F), AcuFocus (F), Voptica SL (I), Voptica SL (P); Henk A.Weeber, AMO Groningen b.v. (E); Pablo Artal, AMO (C), VopticaSL (P), Voptica SL (I), AMO (F), Calhoun Vision (F), CalhounVision (C), AcuFocus (C)Support: Ministerio de Ciencia e Innovación, Spain (grantsFIS2010-14926 and CSD2007-00013) and Fundación Séneca(Region de Murcia, Spain), grant 4524/GERM/06 and AMO.Program Number: 1285Presentation Time: 10:00 AM - 10:15 AMImpact of the Retinal Reflection on the Wide-Angle Point SpreadFunction of the Human EyeHarilaos S. Ginis 1, 2 , Guillermo M. Perez 3 , Alexandros Pennos 1 , JuanM. Bueno 1 , Pablo Artal 1 . 1 Laboratorio de Optica, UNIVERSIDADDE MURCIA, Murcia, Spain; 2 Institute of Vision & Optics,University of Crete, Heraklion, Greece; 3 Voptica SL, Murcia, Spain.Purpose: Objective measurements of scattered light in the livinghuman eye require the analysis of double-pass (DP) retinal images.The inherent wavelength-dependent properties of the retinalreflection may influence these measurements. The aim of this workwas to measure the wide-angle Point Spread Function (PSF) atdifferent wavelengths to better understand the role of the fundusoptical properties and to identify the optimal conditions for visuallyrelevant scattering measurements.Methods: The instrument, based on the DP principle, used anextended-source, and allowed the recording of the wide-angle PSFfor different wavelengths. A liquid-crystal wavelength tunable filterwas used to select six different wavelengths ranging from 500 to 650nm. Series of uniformly illuminated disks with angular size up to 8.1degrees in radius were sequentially projected onto the ocular fundus.A technique previously reported (Ginis et al., J. Vision (2012)) wasemployed to analyze the DP images and reconstruct the wide-anglePSF for each wavelength. The complete series of measurements wereperformed in 10 healthy Caucasian subjects with differentpigmentation. As an indication of the amount of measured scatter, weobtained the value of the PSF for small (0.5 degrees) and large (7degrees) angles.Results: For small angles, there was a wavelength dependence thatmatches the transmittance spectrum of oxy-hemoglobin, whatsuggests that diffuse light from the fundus was part of thereconstructed PSF at longer wavelengths. This contribution of thefundus is more important for wavelengths longer than 600nm.Therewas a different behavior depending on subjects’ pigmentation withlight-colored eyes exhibiting higher intensities of scattered light andwithout dependence on wavelength. For larger angles, scatter wasnearly independent of wavelength and subjects’ pigmentation.Conclusions: The central part of the wide-angle PSF in the eye isaffected by the wavelength dependent properties of the retinalreflection, which are closely related to subject’s pigmentation. Atthose small angles, measurements using wavelengths shorter than600nm might be better correlated with scatter affecting vision.However, the impact of the retinal reflection in the values of the PSFat larger angles did not depend on the measuring wavelength.Commercial Relationships: Harilaos S. Ginis, Universidad deMurcia (P); Guillermo M. Perez, VOPTICA (E); AlexandrosPennos, None; Juan M. Bueno, None; Pablo Artal, AMO (C),Voptica SL (P), Voptica SL (I), AMO (F), Calhoun Vision (F),Calhoun Vision (C), AcuFocus (C)Support: Supported by the Ministerio de Ciencia e Innovación,Spain (grants FIS2010-14926 and CSD2007-00013), FundaciónSéneca (Region de Murcia, Spain), grant 4524/GERM/06 and EUITN OpAL (PITN-GA-2010-264605).233 Binocular Vision and Age Effects on VisionMonday, May 06, 2013 8:30 AM-10:15 AMExhibit Hall Poster SessionProgram #/Board # Range: 1517-1529/B0303-B0315Organizing Section: Visual Psychophysics / Physiological OpticsProgram Number: 1517 Poster Board Number: B0303Presentation Time: 8:30 AM - 10:15 AMOblique effects in V2 neurons of infant macaque monkeysXiaofeng Tao 1 , Bin Zhang 1, 2 , Guofu Shen 1 , Earl L. Smith 1 , Yuzo M.Chino 1 . 1 College of Optometry, Unitersity of Houston, Houston, TX;2 College of Optometry, NOVA Southeastern University, FortLauderdale, FL.Purpose: The neural basis of oblique effects is elusive. Wepreviously reported that the spatial matrix of facilitatory subfields(subunits) in the receptive fields of individual V2 neurons in adultmonkeys exhibits an orientation anisotropy; the homogeneity of thesubfields is greater if a neuron preferred the cardinal orientationscompared to oblique orientations (Tao et al, 2012). In this study, weasked whether a similar orientation anisotropy (an oblique effect)exists in V2 of infant monkeys shortly after birth. In addition weasked whether or not we find an oblique effect if we analyze theresponses of a large number of adult V2 neurons (> 600 units) usingsine-wave grating stimuli.Methods: Extracellular recording was made in individual V2 neuronsof anesthetized and paralyzed 4-, 8-, and 16-week-old macaquemonkeys. The results from infants were compared to those obtainedin adults. Standard sine-wave grating stimuli were initially used todetermine the preferred orientation, spatial frequency and size ofneuron’s receptive fields. Neurons were classified into vertically,horizontally, or obliquely oriented units after we determined thepreferred orientation of each neuron. This was followed by the use ofdynamic two dimensional noise stimuli and a reverse correlation(LSRC) method to obtain the spatial matrix of subfields withfacilitatory profiles.©2013, Copyright by the Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Go to iovs.org to access the version of record. For permissionto reproduce any abstract, contact the ARVO Office at arvo@arvo.org.
ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group – Visual Psychophysics / Physiological OpticsResults: 1) Using grating stimuli, we found that V2 neurons in adultmonkeys show an oblique effect. 2) The oblique effect in the spatialmatrix of subfields was absent in V2 at 4 and 8 weeks of age butemerged sometime between 8 and 16 weeks; the average maximalorientation differences between adjacent subfields were smaller forthose neurons preferring the cardinal orientations.Conclusions: 1) Our results with grating stimuli represent the firstdemonstration of oblique effects in monkey extrastriate cortex. 2)The oblique effect in the spatial matrix of facilitatory subfields maynot be present at birth, but appears to result from experiencedependentmaturation of the connections between V1 and V2.However, the effects of optical factors including higher-orderaberrations have not been ruled out.Commercial Relationships: Xiaofeng Tao, None; Bin Zhang,None; Guofu Shen, None; Earl L. Smith, Ziess (P); Yuzo M.Chino, NoneSupport: NIH Grant R01-EY008128 (YMC), R01-EY003611 (ELS),Core Grant P-30-EY007751Program Number: 1518 Poster Board Number: B0304Presentation Time: 8:30 AM - 10:15 AMInterocular acuity differences alter the spatial frequency tuningof stereopsisAshley Craven 1 , Truyet Tran 1 , Kevin Gustafson 1 , Thomas H. Wu 1 ,Kayee So 1 , Dennis M. Levi 1, 2 , Roger W. Li 1, 2 . 1 School of Optometry,University of California-Berkeley, Berkeley, CA; 2 Helen WillsNeuroscience Institute, University of California-Berkeley, Berkeley,CA.Purpose: It is well known that interocular acuity differences result inreduced stereo acuity. However, previous studies have used tests thatare broadband in their spatial frequency content. The purpose of thepresent study was to investigate the effects of interocular differencesin acuity on the spatial frequency tuning of stereoscopic depthperception.Methods: The visual stimulus consisted of two horizontallyseparated square blocks, one presented to each eye. Each blockcontained a Gabor target patch surrounded by four Gabor referencepatches. Binocular disparity was introduced by shifting the twoGabor targets in opposite directions (controlled by 2 interleavedstaircases), and a haploscope was used to enable binocular fusion.Stimulus spatial frequency ranged from 1-20 cyc/deg. The visual taskwas to determine the stereoscopic depth of the Gabor target (crosseddisparity: in front of / uncrossed disparity: behind) relative to the fourreferences. Five adult observers with corrected-to-normal vision weretested. Bangerter foils were used to reduce visual acuity in thedominant eye. Stereothresholds were measured for a range of acuitydifference: from 1 to 8 letter-lines on a standard LogMAR letterchart.Results: The stereoacuity versus spatial frequency function isbasically the inverse of a typical contrast sensitivity function, withthe optimum spatial frequency at 5- 10 cyc/deg. Increasing theinterocular acuity difference degrades stereo thresholds selectively athigh spatial frequencies, gradually shifting the optimum frequency tolower spatial frequencies. Interestingly, stereopsis for low frequencytargets was only mildly affected even with an acuity difference of asmuch as eight letter-lines (0.8 LogMAR).Conclusions: The current study shows that interocular acuitydifferences result in spatial frequency specific losses of stereopsis.These findings have important clinical implications for understandingboth the sparing of coarse stereopsis and the deficits in fine stereopsisin anisometropic amblyopia.Commercial Relationships: Ashley Craven, None; Truyet Tran,None; Kevin Gustafson, None; Thomas H. Wu, None; Kayee So,None; Dennis M. Levi, None; Roger W. Li, NoneSupport: NIH Grant R01EY01728Program Number: 1519 Poster Board Number: B0305Presentation Time: 8:30 AM - 10:15 AMEnhancing stereoacuity through perceptual learning in normalvision: Specificity for spatial frequency and orientationTruyet Tran 1 , Kayee So 1 , Calvin Nguyen 1 , Tszwing Leung 3 , SandyChat 1 , Dennis M. Levi 1, 2 , Roger W. Li 1, 2 . 1 School of Optometry,University of California-Berkeley, Berkeley, CA; 2 Helen WillsNeuroscience Institute, University of California-Berkeley, Berkeley,CA; 3 School of Optometry, The Hong Kong Polytechnic University,Hung Hom, Hong Kong.Purpose: To investigate whether practicing a stereoscopic depthdetection task enhances stereoacuity in adults with normal vision andwhether the learning effects, if any, transfer across target spatialfrequencies and carrier orientations.Methods: The visual stimulus consisted of two horizontallyseparated square blocks, one presented to each eye. Each blockcontained a Gabor target patch surrounded by four Gabor referencepatches. A haploscope was used to enable binocular fusion. Thevisual task was to determine the stereoscopic depth of the Gabortarget (in front / behind) relative to the four references. Ten adultobservers with corrected-to-normal vision participated. The trainingprotocol consisted of three training phases (each of 13 sessions). InPhase 1 observers were trained with targets with a vertical carrier of 5cyc/deg (V5, vertical). In Phase 2 they continued to train with thesame spatial frequency, but with an orthogonal carrier orientation(H5, horizontal). They were subsequently required to practice withtargets with a vertical carrier at a higher spatial frequency (V10, 10cyc/deg) in phase 3. Thresholds for each of the three stimulusconfigurations were measured before and after each training phase.Trial-by-trial feedback was provided.Results: Our observers showed a substantial mean improvement of64% in stereo thresholds after practicing with V5 stimuli in phase 1,and the improvement transferred substantially to the other twountrained stimulus configurations (H5: 46% and V10: 56%).Additional significant improvements obtained with subsequent directtrainingin phases 2 (H5: 29%) and 3 (V10: 19%) indicate that thetransfers observed in phase 1 were not complete.Conclusions: Perceptual learning can induce functional plasticity forenhancing stereovision in the mature visual system. Our findingscharacterize the magnitude, time course and specificity of visuallearning. This technique might have important applications inrestoring impaired binocular vision in cortical visual disorders.Commercial Relationships: Truyet Tran, None; Kayee So, None;Calvin Nguyen, None; Tszwing Leung, None; Sandy Chat, None;Dennis M. Levi, None; Roger W. Li, NoneSupport: NIH Grant R01EY01728Program Number: 1520 Poster Board Number: B0306Presentation Time: 8:30 AM - 10:15 AMFactors influencing stereoacuity levels after surgery to correctunilateral developmental cataracts in childrenSoo Jung Lee 1 , Nam Eok Kim 2 , Jung Min Park 2 . 1 Haeundae PaikHospital, Busan, Republic of Korea; 2 Ophthalmology, MaryknollMedical Center, Busan, Republic of Korea.Purpose: To evaluate factors influencing stereoacuity after surgery tocorrect unilateral developmental pediatric cataracts.Methods: We retrospectively surveyed 110 patients who hadundergone removal of unilateral acquired developmental cataracts©2013, Copyright by the Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Go to iovs.org to access the version of record. For permissionto reproduce any abstract, contact the ARVO Office at arvo@arvo.org.
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