Cornea - ARVO

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ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - Cornea506 Contact Lens IIThursday, May 09, 2013 8:30 AM-10:15 AMExhibit Hall Poster SessionProgram #/Board # Range: 5453-5490/A0152-A0189Organizing Section: CorneaContributing Section(s): Visual Psychophysics / PhysiologicalOpticsProgram Number: 5453 Poster Board Number: A0152Presentation Time: 8:30 AM - 10:15 AMCorneal confocal and topographical changes with use of rigidcontact lens in keratoconus patients following collagen crosslinkingSri Vatsa Sehra, Jeewan S. Titiyal, Radhika Tandon, NamrataSharma, Rajesh Sinha. Dr Rajendra Prasad Centre for OphthalmicSciences, All India Institute of Medical Sciences, New Delhi, India.Purpose: To assess corneal confocal and topographical changes withuse of rigid gas permeable contact lens (CL) in keratoconus (KC)patients following collagen cross linking (CXL).Methods: A prospective comparative case series was performed inwhich three groups of eyes with primary KC were recruited: Group 1(CXL-CL), 26 eyes which were newly fitted with CL three monthsafter CXL; Group 2 (CXL-SL), 21 eyes with CXL done three monthsback, not fitted with CL; Group 3 (KC-CL), 25 eyes that had neverundergone CXL and were newly fitted with CL. All eyes werefollowed up for six months after recruitment. Confoscan CS4(NIDEK, Gamagori, Japan), Pentacam (Oculus, Lynnwood, WA,USA), Videokeratography (Atlas 9000, Carl Zeiss Meditec, Dublin,CA, USA) and Specular endothelial microscopy (EM 1000, Tomeycorp, Nagoya, Japan) were performed in all eyes at baseline and atone; three and six months follow up.Results: CXL-CL and KC-CL showed increase in the superficialepithelial cell size, decrease in basal epithelial cell density anddecrease in the sub-basal nerve plexus fibre count and branchingcount over follow up; whereas CXL-SL showed decrease insuperficial epithelial cell sizes, increase in basal epithelial density andregeneration of sub-basal nerve plexus (Table 1). CXL-CL had aregression of 0.93D in mean keratometry and 1.99D in maximumkeratometry (P=0.00 in both); no significant keratometric flatteningwas seen in other groups (Figure 1).Uncorrected visual acuity (UCVA) improved only in CXL-CL from0.97 ± 0.25 logarithm of the minimum angle of resolution (logMAR)units at baseline to logMAR 0.86 ± 0.30 at 6 months (P=0.00). CLusers had better BCVA (P=0.00) than patients using spectacles. Overrefractionshowed a myopic shift of 0.37D in CXL-CL (P=0.00), nosignificant change in over-refraction was seen in KC-CL.Conclusions: CL use after CXL is associated with changes in cornealepithelium and delayed recovery of corneal sub-basal nerve plexus onconfocal microscopy. It is also associated with significant corneaflattening and improvement in UCVA.Confocal microscopy epithelial and sub-basal nerve plexusparameters.Pentacam subtraction maps. a) CXL-CL patient showing centralflattening after 6 months follow up. b) CXL-SL patient showingminimal change after 6 months follow up. c) KC-CL patient showinginferior and central steepening after 6 months follow up.Commercial Relationships: Sri Vatsa Sehra, None; Jeewan S.Titiyal, None; Radhika Tandon, None; Namrata Sharma, None;Rajesh Sinha, NoneProgram Number: 5454 Poster Board Number: A0153Presentation Time: 8:30 AM - 10:15 AMIs the Use of an Integrating Sphere Really Desirable WhenMeasuring Contact Lens Transmittance?Claude J. Giasson 1, 2 , Corinne Deschênes 1 , Vasile Diaconu 1 . 1 Schoolof Optometry, University of Montreal, Montreal, QC, Canada;2 LOEX, CHA, Quebec, QC, Canada.Purpose: The standard indicates that contact lens transmittanceshould be measured with an integrating sphere (IS) in order toinclude the scatter (or indirect transmittance). To compare contactlens transmittance obtained with and without an integrating sphereand to evaluate how much light is lost in measurements done with anIS.Methods: After a baseline percent transmittance measurement of aquartz chamber filled with saline, the total and direct percent©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 - Corneatransmittance of the chamber with a contact lens (Encore 100) wererespectively measured 4 times with and without an integrating spherewith a scanning spectrophotometer (Cary 5000, Varian) in the rangeof 200 to 800 nm. In other experiments, relative light levels weremeasured with and without the measuring chamber with and withoutthe IS in order to estimate how much of the signal was lost upon theaddition of the measuring chamber. Differences between total anddirect transmittance for contact lenses were tested for significance at550nm with an independent t test using the SPSS 17.0 software forWindows.Results: There were no significant differences at 550 nm between thetotal (100.8 ± 8.5%) and direct transmittance (98.3 ± 0.2%) whentested with an independent t test. The standard deviations of totaltransmittance measurement were consistently larger than the onesobtained without the integrating sphere. At 550 nm, the ratio of lightintensities measured in the absence of the chamber filled with salineto the one measured with the chamber with saline represented 46% ofthe signal when the IS was in position and 92% when it was not.Conclusions: The use of an integrating sphere when measuring thetransmittance of a contact lens allows to include the diffusion of thecontact lens in the measurement. However, in our system, the lightintensity is drastically decreased by the simple addition of a wet cellin front of an integrating sphere that reduce the signal and mayincrease the noise.Commercial Relationships: Claude J. Giasson, None; CorinneDeschênes, None; Vasile Diaconu, NoneProgram Number: 5455 Poster Board Number: A0154Presentation Time: 8:30 AM - 10:15 AMPeripheral Defocus with Spherical and Bifocal Soft ContactLensesDavid A. Berntsen, Carl E. Kramer. College of Optometry,University of Houston, Houston, TX.Purpose: Peripheral myopic defocus has been hypothesized to slowthe progression of myopia. We describe peripheral defocus whenmyopic eyes are corrected with spherical and center-distancemultifocal soft contact lenses while looking at distance and nearobjects.Methods: Twenty-five subjects with spherical contact lens-correctedrefractive error of -0.50 to -6.00 DS participated. A modified openfieldautorefractor was used to measure refractive error of the righteye while wearing a spherical soft contact lens (Biofinity) and acenter-distance multifocal soft contact lens with a +2.50-D add(Biofinity Multifocal "D" Lens). Measurements were made centrallyand along the horizontal meridian at ±20°, ±30° and ±40° from theline of sight both at near (30-cm demand) and at distance (undercycloplegia). Lens type and measurement starting location wererandomized. Repeated-measures ANOVAs with post-hoc t-tests wereused for analysis.Results: The mean (±SD) age and central spherical equivalentrefractive error were 23.8 ± 1.3 years (range: 22 to 27 years) and -3.62 ± 1.56 DS, respectively. At distance, mean spherical equivalentrefractive error (defocus) when wearing contact lenses wassignificantly more hyperopic with the spherical lens than with themultifocal lens (p
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