Visual Psychophysics / Physiological Optics - ARVO

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ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group – Visual Psychophysics / Physiological OpticsProgram Number: 4067Presentation Time: 9:30 AM - 9:45 AMComparability of Visual Performance of Individuals with LowVision in Real and Virtual Street IntersectionsLei Liu, Ellen L. Bowman. School of Optometry, University ofAlabama at Birmingham, Birmingham, AL.Purpose: Low Vision Orientation & Mobility (O&M) evaluation andtraining are typically performed in streets and street intersections.While effective, the efficiency of the practice can be greatlyimproved by employing computer-generated virtual street scenarios.To evaluate the feasibility of virtual O&M training, we comparedvisual performance of low vision patients in real and virtual streetintersections.Methods: A semi-CAVE virtual reality simulator was built. Itconsisted of a game computer, 3 digital projectors, three 2.4x1.9 mscreens (>180 o deg horizontal) and surrounding sound. Four virtualstreet intersections were built based on 4 real intersections in anurban environment. Google Street, Geographic Information Systemand on-site photos/videos were used to match the physical layout andsurrounding, traffic controls, and vehicle and pedestrian traffic of thereal and virtual intersections. Multiple crossing scenarios were set ateach intersection. Ten legally blind subjects with adequate priorO&M training performed 10 visual tasks in both real and virtualintersections. These tasks included identifying traffic elements,determining intersection layout and choosing the safest time to cross.The performance was rated pass or fail by two certified O&Mspecialists. Agreement between performance in corresponding realand virtual intersections was compared.Results: Data from corresponding real and virtual intersections wasorganized into a 2x2 contingency table. The overall, positive andnegative agreements were 83.3%, 89.4% and 68.6%, respectively,indicating that if a subject could perform a task in a real intersection,it was highly likely that she could also perform the same task in avirtual version of the intersection, and vice versa. The kappacoefficient was 0.59, bordering moderate and substantial agreement.A McNemar analysis of paired binary data showed an exactsignificance of 0.824, indicating no difference in performancebetween real and virtual intersections.Conclusions: Persons with low vision exhibited similar abilitieswhile performing visual tasks in real and virtual street intersections.The agreement suggested that computer-generated traffic scenesprovided sufficient visual and auditory information for low visionpatients to perform O&M tasks. Virtual reality has the potential tobecome a useful supplement to tradition low vision rehabilitationtraining.Commercial Relationships: Lei Liu, None; Ellen L. Bowman,NoneSupport: NIH Grant 1R21EY0195491.5s in random order, through adaptive optics to correct theaberrations of the eye. The PSV images (50/50 energy content) wereobtained from the combination of a focused image superimposed to adefocused version of the same image. At least 18 defocus conditions(0-3D) were subjectively ranked (10 repetitions). In addition, opticalquality was evaluated as a function of defocus, from the PSV and PDPoint Spread Functions (PSF), using the Modulation TransferFunction (MTF) at different frequencies as a metric.Results: As expected, images without defocus were perceived assharp (score s=5) in all subjects and conditions. The perceptualweighted rank systematically dropped for PD at a rate of 9.0±4.0 s/D,with the images perceived as completely blurred (s=0) from 0.6 Donwards. PSV images provided a similar decrease as their defocuscomponent increased, in the 0-0.3D range. However, in 3 subjects thescore reached a minimum at 0.5D (s=2.1±0.4) and then it waspartially recovered back towards sharpness (s=3.5 at 1.2D),remaining stable afterwards. The 4th subject showed a similar trendjudging PSV images but without a minimum. The objectivesimulations predicted the perceptual judgment trends, as well as thedifferences between judgments of PD and PSV images. MTF@20c/deg decreased sharply with defocus in PD, but reached a minimum(0.42 at 0.5 D) and recovered a stable level (0.50 from 1.5D) in PSV.Averaged MTFs (15-25 c/deg) provided the most accuratepredictions.Conclusions: As opposed to the common idea that simultaneousvision retinal images (as those found in multifocal contact orintraocular lenses) are severely optically degraded, but later restoredin neural processes, we have found a good correspondence betweenpure subjective perception experiments and pure optical simulations.Although our findings do not preclude for possible effects of neuraladaptation, neural effects seem to be secondary in the perceptualjudgment of sharpness in PSV.Program Number: 4068Presentation Time: 9:45 AM - 10:00 AMOptical quality and subjective judgments of blur under puresimultaneous visionCarlos Dorronsoro, Aiswaryah Radhakrishnan, Lucie Sawides,Susana Marcos. Instituto de Optica, CSIC, Madrid, Spain.Purpose: To compare retinal image quality and subjective imagesharpness under pure bifocal simultaneous vision (PSV) across awide range of addition values.Methods: Four subjects performed a weighted rank psychophysicalexperiment to grade (from totally blurred to totally sharp, 0 to 5) theperceptual quality of PSV images. As a control condition, theperceptual quality of purely defocused (PD) images was alsoassessed. Computer generated images of a face were observed, forCommercial Relationships: Carlos Dorronsoro, EssilorInternational (F); Aiswaryah Radhakrishnan, None; LucieSawides, None; Susana Marcos, Essilor (F), PCT/ES2012/070185(P)Support: FIS2011-25637; ERC-2011-AdG-294099; EU Marie CurieFP7-PEOPLE-2010-ITN #26405©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 Optics417 Accommodation and Presbyopia CorrectionWednesday, May 08, 2013 8:30 AM-10:15 AMExhibit Hall Poster SessionProgram #/Board # Range: 4250-4283/B0287-B0320Organizing Section: Visual Psychophysics / Physiological OpticsProgram Number: 4250 Poster Board Number: B0287Presentation Time: 8:30 AM - 10:15 AMThe Influence of Multifocal Lenses on Fine Motor TasksRupal Lovell-Patel 1, 2 , Matthew A. Timmis 2 , Shahina Pardhan 2 , PaulMcCarthy 1, 2 . 1 Vision and Hearing Sciences, Anglia RuskinUniversity, Cambridge, United Kingdom; 2 Vision and Eye ResearchUnit, Anglia Ruskin University, Cambridge, United Kingdom.Purpose: Literature suggests that multifocal lenses are associatedwith a decreased performance for a variety of tasks includingnegotiating steps, obstacles, driving and reading at certain distances,when compared to single vision lenses. In daily life we regularlyperform other motor tasks, such as reaching and grasping an object.Currently, there is no evidence based data on how multifocal lensesaffect the performance of such fine motor tasks when compared tosingle vision lenses.Methods: 12 presbyopic subjects who were habitual multifocalspectacle wearers took part in the study. Performance was comparedfor multifocal lenses and single vision lenses which were prescribedfollowing a comprehensive vision assessment and an analysis of thedistances at which the tasks were carried out. Subjects had aminimum visual acuity of 0.00 LogMAR. Participants completed 3different fine motor tasks wearing both types of correction; objectwidth estimation, reach-and-grasp and transport-and-placement.Hand and head movements were captured by a 3-D motion capturesystem.Results: Data were analysed using ANOVA. Peak grip aperture wassignificantly larger when grasping the large compared to small object(p < .001). Participants also showed greater error when positioningthe large compared to small object (p < .001). For the reach-andgrasptask: onset time, overall movement time, peak velocity, peakgrip aperture, deceleration time and velocity corrections were notsignificantly affected by spectacle type (p>0.05). Interestingly, headflexion was also not affected by the spectacle type (p > .05). For theobject width estimation task: no significant difference was obtainedin the perceived aperture width between the spectacle types. Fortransport-and-placement: movement time, peak velocity, decelerationtime, velocity corrections, head rotation and error in object placementwere unaffected by spectacle type (p > .05).Conclusions: The type of spectacle lens did not affect the fine motortasks which encompassed a range of visual angles that would lieoutside the multifocal lenses’ intermediate corridor. Datademonstrates that habitual multifocal spectacle wearers can carry outfine motor tasks such as reaching and grasping just as competently asthey can with single-vision lenses.Commercial Relationships: Rupal Lovell-Patel, None; MatthewA. Timmis, None; Shahina Pardhan, None; Paul McCarthy, NoneProgram Number: 4251 Poster Board Number: B0288Presentation Time: 8:30 AM - 10:15 AMAccommodative Lag, Facility and Phoria with Multifocal ContactLensesJiyoon Chung 1 , Ravi C. Bakaraju 1 , Cathleen Fedtke 1 , Jerome Ozkan 1 ,Klaus Ehrmann 1, 2 , Darrin Falk 1 , Arthur Ho 1, 2 , Brien A. Holden 1, 2 .1 Brien Holden Vision Institute, Sydney, NSW, Australia; 2 School ofOptometry and Vision Science, University of New South Wales,Sydney, NSW, Australia.Purpose: To compare the accommodative lag, facility and phoriameasurements of myopic participants fitted with various commercialcontact lens designs.Methods: Forty myopic, non-presbyopic, subjects were randomizedto be fitted bilaterally, with a single vision control lens (Air OptixAqua) and two of four multifocal (MF) lenses (Proclear Distance andNear MF, Air Optix Aqua MF and PureVision MF) on a daily wearbasis. Subjects wore each lens type for a minimum of 8 days over 4scheduled (baseline and 3 follow-up) visits with a 1-week wash-outbetween lens types. Static accommodative responses were assessedwith the EyeMapper at all visits. Five repeats were performed in afogged state (+1D) and at four object vergences from -2 to -5D (1Dsteps). Paraxial curvature matching of the wavefront aberration mapyielded the spherical equivalent. Accommodative facility and phoria(at distance and near) were evaluated using ± 2D flippers and Howellcard, respectively. To reduce the effect of between-visit variability,the data was averaged over the four visits.Results: At +1D fogging, all lens types produced a myopic shift.With the control lens, the accommodative response function wasrelatively linear (slope = 0.82). Three centre-near MFs (Air Optix,PureVision and Proclear Near) all demonstrated accommodative leadat -2D, optimal response at -3D, and lag at -4 and -5D objectvergences. Proclear Distance produced lag over all test vergences. AllMFs produced lower accommodative facility compared to controllens (19.2 cycles / min, p
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Visual Psychophysics / Physiological Optics - ARVO

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