Visual Psychophysics / Physiological Optics - ARVO

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