Visual Psychophysics / Physiological Optics - ARVO

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ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group – Visual Psychophysics / Physiological OpticsMethods: Detection thresholds were previously measured in thedark-adapted fovea for spots from 0.3' to 25' in diameter (550nm, 10-30ms), viewed through either a 2 mm (conventional optics, 4subjects) or 6 mm pupil (adaptive optics aberration correction, 5subjects). Thresholds and psychometric function slopes werecompared with predictions from analytic and Monte-Carlo modelswith different summation strategies given detection uncertainty,Poisson noise, and cone mosaic granularity.Results: Average change in log threshold with log stimulus area was0.12±0.03 for stimuli up to 4-10' diameter, precluding both a singleunit size and the optimal stimulus-matched strategy. Data wereconsistent with spatial uncertainty of at least 25'. Model comparisonsuggests suboptimal combination across multiple-sized units, wheresmaller units exhibit relatively more post-receptoral noise, with thesmallest unit no larger than the smallest stimulus (~0.5' retinal fullwidthhalf maximum), and the largest unit 4-10' in diameter. At leasttwo different unit sizes are required to describe the data. Althoughmany different unit sizes are required for performance approachingoptimal stimulus-matched summation, independent combinationacross two sizes reduces efficiency by only ~0.1 log unit. With a 10'largest unit (roughly parasol receptive field center size) and quantumefficiency of 0.11-0.35, dark noise is estimated at 9-435events/cone/s.Conclusions: Dark-adapted foveal detection as a function of stimulussize is consistent with independent combination across at least twodifferent sized units, the largest and smallest of which are consistentwith midget and parasol ganglion cell receptive field sizes. Anindependent detection strategy across midget and parasol ganglioncells is expected to perform only slightly worse than the optimalstimulus-matched strategy, given noise and uncertainty constraints.Commercial Relationships: Darren E. Koenig, None; Heidi J.Hofer, NoneSupport: NIH ROI EY019069, P30 EY07551Monocular and binocular presentation were compared, as well asresults obtained with natural or dilated pupil.Results: All subjects completed the test successfully. Binocularpresentation reduced threshold by ~0.15 log units. Intra-subjectrepeatability was >90%. We found no difference in the resultsobtained with natural or dilated pupils. A flickering stimulus did notshow advantages over a constant presentation.Conclusions: The Tuebingen Scotopic Threshold Test allows forquick and easy assessment of the sensitivity of the dark-adapted eye.The recording takes only 5 minutes (w/o dark adaptation), can bedone with natural pupils and is comfortable for the patient. Resultsobtained with the TSTT show a high correlation to similar tests. Thismakes the TSTT to a well suited tool for testing children.This project and study is supported through TREATRUSH(HEALTH-F2-2010-242013), a European Collaborative project -supported by the European Commission under the 7th FrameworkProgram.Program Number: 3015 Poster Board Number: C0178Presentation Time: 8:30 AM - 10:15 AMQuick and easy light sensitivity assessment of the dark adaptedeye: The Tuebingen Scotopic Threshold Test (TSTT)Torsten Strasser, Hana Langrová, Anne Kurtenbach, Ditta Zobor,Dominic Hillerkuss, Eberhart Zrenner. Institute for OphthalmicResearch, Centre for Ophthalmology, Tuebingen, Germany.Purpose: Light sensitivity of the dark-adapted eye is a valuableindicator of retinal function. Changes in light sensitivity are observedin many retinal disorders like Retinitis pigmentosa, CSNB, or invitamin A deficiency. Light sensitivity is usually tested using darkadaptometry: after transient exposition to bright light the darkadaptationcurve and the final threshold are measured. This procedureis time-consuming and uncomfortable, especially for children. Withinthe EU-project TREATRUSH, we developed a test for assessing thescotopic threshold for early detection of Usher's syndrome.Methods: The TSTT has 2 panels for scotopic and photopicstimulation. Each panel has a size of 7×10cm, consisting of 35individually addressable LED bars, thus allowing to use variousstimulus shapes. The centerpiece of the TTST is a microcontroller(ATmega8515, Atmel Corp.), running a self-developed software.Stimulus luminance is tuned by pulse-width modulation andadjustable in 100 steps between -3 to -1 log cd/m 2 . Using filters, thiscan be extended from -8 to -1 log cd/m 2 . The luminance graduallyincreases until a perception is indicated. The patient names the shapeand the examiner confirms or discards the response, thusdiscriminating correct answers from false-positives. If confirmed, theluminance is decreased and the procedure is repeated.Feasibility and repeatability were tested in 11 subjects (10-68yrs).Commercial Relationships: Torsten Strasser, None; HanaLangrová, None; Anne Kurtenbach, None; Ditta Zobor, None;Dominic Hillerkuss, None; Eberhart Zrenner, Retina Implant AG(F), Retina Implant AG (I), Retina Implant AG (C), Retina ImplantAG (P), QLT Inc (C), Servier, Paris (C), Steinbeis GmbH&CoKG,Stuttgart (I), Steinbeis GmbH&CoKG, Stuttgart (C), Neurotech, USA(C), Pfizer, USA (C)©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 OpticsProgram Number: 3016 Poster Board Number: C0179Presentation Time: 8:30 AM - 10:15 AMDark Adaptation and the effect of Oxygen Inhalation in CysticFibrosisRachel Hiscox 1 , Christine Purslow 2 , Rachel V. North 1 , Ian Ketchell 3 ,Katharine Evans 1 . 1 School of Optometry and Vision Sciences,Cardiff University, Cardiff, United Kingdom; 2 School of HealthProfessions, Plymouth University, Plymouth, United Kingdom; 3 AllWales Adult Cystic Fibrosis Centre, University Hospital Wales,Cardiff, United Kingdom.Purpose: Previous research has shown impaired measures of darkadaptation in cystic fibrosis (CF), with the cause generally attributedto concomitant vitamin A deficiency. However, other factorsincluding CF-related diabetes (CFRD) may influence these results.Impaired dark adaptation in Type 1 and 2 diabetics improves uponoxygen inhalation and has therefore been attributed to retinalhypoxia. The purpose of this preliminary study was to evaluate theeffect of oxygen inhalation on dark adaptation in CF, to determine theunderlying cause of impairment.Methods: Dark adaptation was assessed in 9 CF (5 CFRD, 4 non-CFRD) and 9 age, gender and ethnicity-matched controls using acustom made computerised dark adaptometer to present an 11°achromatic stimulus centred on the fovea. All CF subjects werevitamin A sufficient. Following pupil dilation, a Maxwellian viewoptical system was used to administer an 82% cone and 75% rodphotopigment bleach. Subsequently, threshold was monitored for 25minutes whilst the patient inhaled either medical air or 100% oxygen(selected at random) through a 60% venti mask. This procedure wasrepeated for the second gas following a 15 minute wash out period.Threshold recovery parameters were modelled and the cone timeconstant of recovery (τ), final cone and final rod thresholdsdetermined. Relationships were evaluated using paired and unpairedT-tests as appropriate.Results: Final rod threshold was significantly elevated in CF subjectscompared to controls when inhaling medical air, -4.54 and -4.64 logcd/m 2 respectively (p=0.03). Oxygen inhalation had no significanteffect on any parameter for controls. Oxygen inhalation in CFsubjects caused a significant decrease in final rod threshold comparedto medical air, -4.66 and -4.54 log cd/m 2 respectively (p=0.04). Whenanalysed according to CFRD status, the CFRD group was found tohave a significantly elevated final rod threshold compared to the non-CFRD group when inhaling medical air, -4.47 and -4.64 log cd/m2respectively (p=0.03). This difference was not present when inhalingoxygen.Conclusions: This study has shown final rod threshold to besignificantly elevated in CF, particularly in those with CFRD, withrecovery to normal levels upon inhalation of oxygen. For the firsttime, this observation suggests that CFRD subjects experienceimpaired dark adaptation secondary to retinal hypoxia, indicatingsimilarities to Type 1 and 2 diabetics.Commercial Relationships: Rachel Hiscox, None; ChristinePurslow, None; Rachel V. North, None; Ian Ketchell, None;Katharine Evans, NoneSupport: School of Optometry and Vision Sciences, CardiffUniversityProgram Number: 3017 Poster Board Number: C0180Presentation Time: 8:30 AM - 10:15 AMCharacteristics of Color Visual Acuity by Step Changes ofBackground Luminance in Young Subjects of Normal EyesYoshiki Tanaka 1 , Kiyoshi Tanaka 1 , Sho Yokoyama 2 , HidekiNakamura 2 , Kazuo Ichikawa 2 , Shoko Tanabe 3 . 1 Faculty ofEngineering, Shinshu University, Nagano, Japan; 2 Ophthalmology,Social Insurance Chukyo Hosp., Nagoya, Japan; 3 Chukyo Eye Clinic,Nagoya, Japan.Purpose: Color Visual Acuity (CVA) is the visual acuity thatmeasures from colored Landolt ring on the background of achromaticcolor and that is the measure for evaluation of visual function forcolors in daily life. In our previous research, we measured CVA ofyoung normal subjects in the case of the background luminance ofthe color 30 [cd/m 2 ] (same luminance with Landolt ring’s color) and100 [cd/m 2 ]. In the result, for the background luminance of 100[cd/m 2 ], CVAs of all colors were almost the same value; and for thebackground luminance of 30 [cd/m 2 ], the CVAs of Blue-Yellow axisof color were higher than the other colors. Then, we further examinedthe changes of CVA for gradual changes of background luminance.Methods: Four normal eyes of 4 subjects (4 males) were enrolled inthis study. The mean age was 21.8 years old (range 21-22 years).They had no history of ocular disease (including color anomaly) orsurgery. All of them had best corrected visual acuity of 20/13. We setthe background color as white point of the standard light D65, andLadnolt ring was colored with four colors (“Red” and “Green” for theRed-Green axis of color, “Green-Yellow” and “Blue-Purple” for theGreen-Yellow axis of color) used in New Color Test (LuneauOphtalmologie).The luminance value of Landolt ring was 30 [cd/m 2 ]as a fixed value, and background was from 50 to 30 [cd/m 2 ] and from15 to 30 [cd/m 2 ].Results: There was significant difference for the colors of G(between 50 and 30 [cd/m 2 ]), GY (between 50 and 30, 15 and 30[cd/m 2 ]), BP (between 50 and 30, 15 and 30, 15 and 28 [cd/m 2 ])(p
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