Visual Psychophysics / Physiological Optics - ARVO

ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group – Visual Psychophysics / Physiological Opticsboth centrally and peripherally located stimuli using a standard 2-IFCtask.Results: We found a characteristic relationship that depended onmodulator disparity spatial frequency. At high modulator disparityspatial frequencies (>1 c/d), there is an optimal ratio of around 2.6,whereas at low modulator disparity spatial frequencies, there is anoptimal absolute carrier luminance spatial frequency (i.e., 3 c/d). Inthe periphery, vision is restricted to modulator disparity spatialfrequencies below 1 c/d and, as a consequence, follows the aboverule, there is an optimum absolute carrier luminance spatial frequencythat reduces in spatial frequency with increasing eccentricity.Conclusions: This finding is consistent with there being more thanone channel processing global stereo. This is subsequently confirmedusing a 2x2 AFC detection/discrimination paradigm. Furthermore,because of the different carrier/modulator relationships in central andperipheral vision, peripheral global stereo cannot be simply related tocentral global stereo by a scaling factor and thus cannot be simplydue to cortical magnification as previously proposed.Commercial Relationships: Robert F. Hess, None; Nirel Witz,NoneSupport: NSERC (#46528-11)Program Number: 2659Presentation Time: 8:45 AM - 9:00 AMEffect of inter-ocular differences in blur on spatial and stereoresolutionSowmya Ravikumar 1 , Bjorn Vlaskamp 2 , Martin S. Banks 1 . 1 VisionScience, University of California Berkeley, Berkeley, CA; 2 PhilipsResearch, Eindhoven, Netherlands.Purpose: Monovision—setting the refraction of one eye to adifferent value than the other—is a procedure for dealing withpresbyopia. The difference in refractions for the two eyes should bethe appropriate value for maximizing visual performance, but there islittle research on what the appropriate value is. We know that bothvisual acuity and stereoacuity worsen as blur increases. However,visual-acuity tasks can in principle be performed when one eye issuppressed, but stereo tasks cannot. Thus, visual acuity might belimited by image quality in the better eye while stereoacuity might belimited by the poorer eye. Some previous observations are consistentwith these expectations. Indeed, blur in one eye can be moredetrimental to stereoacuity than the same blur in both eyes (blurparadox).Methods: We compared visual acuity and stereoacuity in the sameobservers with the same blur manipulations. Stimuli were displayedbinocularly using a custom stereoscope. Accommodation wasparalyzed with cyclopentolate. An artificial pupil set the effectiveaperture to 4mm. Blur was introduced with ophthalmic lenses. Wemeasured visual acuity with a letter-identification task. We measuredstereoacuity using a random-dot stereogram that created sinusoidalcorrugations in depth oriented +/- 20 degrees about the horizontal;subjects indicated which of two corrugation orientations waspresented.Results: The results were consistent with our expectations. Forvarying amounts of blur in the two eyes, visual acuity closelyconformed to the better eye’s performance while stereoacuity waslargely limited by the worse eye’s blur. Monocular blur had almostno effect on visual acuity, with binocular visual acuity remainingclose to 20/20 with up to 1.5D blur in one eye. For the same amountof blur, stereoacuity decreased by a factor of almost two. When theblur was equal in the two eyes, stereoacuity was slightly better thanwhen the same blur was present in one eye only (e.g., In comparing1.5D in both eyes to 1.5D of blur in one eye only, in one subject,stereo-acuity was 1.98 cpd compared to 1.13 cpd and in anothersubject, stereoacuity was 1.54 cpd compared to 1.37 cpd).Conclusions: The results will help us design monovision protocols ina way that is the best compromise between visual acuity andstereoacuity for various viewing distances.Commercial Relationships: Sowmya Ravikumar, None; BjornVlaskamp, Philips (E); Martin S. Banks, NoneSupport: RO1-EY 12851 to MSBProgram Number: 2660Presentation Time: 9:00 AM - 9:15 AMBinocular combination of optically-induced asymmetricinterocular blurAixa Alarcon 1 , Len Zheleznyak 2, 1 , Martin S. Banks 3 , GeunyoungYoon 1, 2 . 1 Flaum Eye Institute, University of Rochester, Rochester,NY; 2 Institute of Optics, University of Rochester, Rochester, NY;3 Vision Science Program, University of California Berkeley,Berkeley, CA.Purpose: It has been reported that interocular mirror symmetry in theaberrations (or optical blur) is present in the normal population. Thegoal of this study was to investigate the effects of interoculardifferences of monocular blur orientation on binocular blurperception.Methods: Eight cyclopleged subjects were asked to binocularly viewa stimulus under 3 aberration conditions and to match the subjectiveblur by inducing defocus to an unaberrated stimulus in 0.05Dincrements. A binocular adaptive optics vision simulator was used tocorrect subjects’ native aberrations, induce the 3 aberrationconditions and to induce defocus for the blur matching task for a6mm pupil. A monochromatic (550nm) binary noise image withrandom edge orientation served as the stimulus. The aberrationconditions consisted of 0.5 and 1D astigmatism and 1μm coma. Theaberration orientation of the right eye was rotated 0 and 90 degrees(i.e. equivalent and orthogonal, respectively) in the case ofastigmatism and 0, 90 and 180 degrees in the case of coma while theleft eye’s aberration was held fixed at 0 degrees for all conditions. Inthe coma condition, right eye orientations of 0 and 180 degreescorrespond to a binocular mirror asymmetry and symmetry of blurorientation, respectively. Two subjects participated in the blurmatching experiment in the 0.5D astigmatism condition, and 8subjects participated in the remaining conditions.Results: Bilateral equivalent and orthogonal astigmatism of 0.5Dresulted in significantly different blur matches of 0.53±0.05 and0.36±0.09D, respectively (p