Visual Psychophysics / Physiological Optics - ARVO

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.