Cornea - ARVO

ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - CorneaMGs in a patient affected by ASCommercial Relationships: Angelica Dipinto, None; PaoloFogagnolo, None; Davide Allegrini, None; Maurizio Digiuni,None; Luca Migliavacca, None; Chiara Olga Pierrottet, None;Laura Ottobelli, None; Olga Oneta, None; Luca M. Rossetti, NoneProgram Number: 4354 Poster Board Number: C0092Presentation Time: 8:30 AM - 10:15 AMHow Does Increasing Ocular Surface Stimulation AffectBlinking?Ziwei Wu 1 , Carolyn G. Begley 1 , Ping Situ 1 , Adam J. Winkeler 1 , JunZhang 1 , Trefford L. Simpson 2 . 1 Optometry, Indiana University,Bloomington, IN; 2 Optometry and Vision Science, University ofWaterloo, Waterloo, ON, Canada.Purpose: Despite the importance of the blink, its control by ocularsurface sensory input remains controversial. In this study, we testedthe hypothesis that increasing ocular surface stimulation will lead to asignificantly increased blink rate (SIBR) that we defined as a blinkrate (BR) ≥ 2 standard errors from baseline.Methods: To control attention, 10 subjects played a video game(with the screen viewed from 20 cm) while also seated behind a slitlamp biomicroscope. Air flow (AF) was directed toward the centralcornea (15mm distance, temperature= 24 Celsius) through a 0.5mmdiameter tube. Using an ascending method of limits, the AFproducing an approximate SIBR was estimated and then, using amethod of constant stimuli 0, 0.25, 0.5, 0.75, 1 and 1.25 multiples ofthis estimated AF were presented 3 times each (in random order).BR, interblink interval (IBI) and AF were recorded simultaneouslyand custom MATLAB programs determined the SIBR for eachsubject.Results: Mean (±SD) airflow to produce a SIBR was134.9±63.9ml/min (range: 65.5 to 248.8ml/min). There was a linearcorrelation between AF and BR or IBI (Pearson’s correlationcoefficient, r= 0.939 and -0.987, respectively). The baseline (AF= 0)BR was 16.5±6.0 blinks/min and the five tested AFs these were20.3±5.9, 25.8±5.0, 30.0±8.3, 47.0±20.3 and 67.4±27.3 blinks/min.The baseline IBI was 4.5±2.1sec and at the five AFs these were3.5±1.3, 2.6±0.5, 2.4±0.9, 1.6±0.5 and 1.1±0.4sec. Figure 1demonstrates the SIBR for one subject.Conclusions: These results support the hypothesis that AFstimulation of the ocular surface leads to a SIBR when mentalconcentration is controlled, and that the increasing stimulationproduces a linear dose response at the levels of AF tested. Thismethod may allow examination of individual differences in the ocularsurface sensory response to stimulation, which may cause thevariation in SIBR among subjects.Figure 1: SIBR for one subject. The continuous line representschanges in AF from 0 to 174ml/min and each vertical line in thebottom trace represents a blink over the 4 min trial.Commercial Relationships: Ziwei Wu, None; Carolyn G. Begley,Santen, Inc. (C), ohnson & Johnson Vision Care, Inc. (C), ohnson &Johnson Vision Care, Inc. (F); Ping Situ, None; Adam J. Winkeler,None; Jun Zhang, None; Trefford L. Simpson, NoneSupport: National Eye Institute R01EY021794Program Number: 4355 Poster Board Number: C0093Presentation Time: 8:30 AM - 10:15 AMDo Tear Film Thinning Rates Vary Locally?Adam J. Winkeler 1 , Carolyn G. Begley 1 , Richard J. Braun 2 , RobertWelch 1 . 1 School of Optometry, Indiana University, Bloomington, IN;2 Mathematics, University of Delaware, Newark, DE.Purpose: The purpose of this study was to determine whether tearthinning rates differ within and outside areas of tear film break-up(TBU) using fluorescein (FL) imaging corroborated by a secondimaging method, retroillumination (RI).Methods: Mydriacyl (1.0%) and proparicaine (0.5%) were instilledinto the eyes of 6 subjects, followed by 2μl of 2% FL. Subjects keptone eye open as long as possible while a modified slit-lampbiomicroscope simultaneously imaged the tear film by FL and RI.Two areas of the tear film, superior and inferior to the pupil, weresystematically selected for analysis. TFT rates inside and outside ofareas of TBU were calculated over time at each location using theslope of a linear least squares fit of the square root of FL intensity toaccount for FL quenching (Nichols et al, 20120). Surface profilesobtained from FL intensity were correlated with integrated RIintensity for corroboration of changes in slope. TFT estimated inµm/min by assuming a 3µm starting tear film thickness.Results: FL intensity decreased in all subjects over time, reaching aminimum within areas of TBU, suggesting full thickness breaks. TheTFT rates for 2 subjects with very stable tears and minor to no TBUwere 0.0063±0.0018 units/sec (Mean ± SD). The other 4 subjectsdeveloped variable and sometimes extensive TBU with an overallaverage TFT rate of 0.0775±0.0055 units/sec, almost 10x faster thansubjects with stable tears. A subject with immediate TBU after theblink had an overall average TFT rate of 0.1477±0.0424 units/sec.The average TFT inside areas of TBU was 0.1038±0.0444 units/seccompared to 0.0576±0.0565 units/sec just outside and adjacent toTBU. This corresponded to estimated thinning rates of 2.913±1.327µm/min inside TBU areas and 1.150±1.481 µm/min in adjacent areas.The local tear film surface profiles calculated from FL intensity inareas of TBU showed increasing correlation with changes inintegrated RI image intensity as TBU developed.Conclusions: TFT varied markedly within and outside of areas ofTBU, whereas TFT showed slow even declines in a stable tear film.Our results show that spatially local differences in TFT within areasof TBU persist long after visible upward movement of the tear filmceased. Our results suggest that, if evaporation is the mainmechanism accounting for TFT, it may vary locally across the tearfilm during TBU.©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.