Cornea - ARVO

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ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - Corneawith a well-known distance between the electrodes. Two corneastorage media were used: Eusol-C and phosphate buffered salinepH=7.4.The 100-400 μm specimens containing the middle layers of cornealstroma were examined. The 9 specimens of healthy, control corneasfrom Eye Bank were obtained with second microkeratom sectionduring Ultra Thin-DSAEK. The 12 specimens of keratoconus corneaswere manually prepared from corneas removed during penetratingkeratoplasty.Results: The fitting procedure of a theoretical function to theexperimental data allowed us to determine up to three relaxationregions. The narrow peak near 1MHz can be successfully traced bythe Debye relaxation function. This peak is probably responsible forthe dipolar polarization of bound water to collagen molecules as wellas for the polarization of side polar groups in polypeptide chains.Two low frequency relaxation regions are related to diffusiveprocesses with different structural distance parameters, i.e. describingthe spatial arrangement of collagen fibrils in cornea. Peak amplitudeswere increasing upon rising electric field applied from 0.05V to 1V.Comparison between the dielectric responses for normal andkeratoconus corneas showed the significant shift of the ionic peakstowards lower frequencies ωn→ωk, with the ωn/ωk ~2. The observedshift in peak position may correspond to the increase in the averagestructural distance of different molecular compartments present inkeratoconus cornea.Conclusions: It has been shown that the method can be utilized tofollow relative changes in the spatial molecular structure ofkeratoconus corneas with respect to the normal tissue. It is alsoconsidered that the method have a great potential to be used forstructural analysis of biological systems in vivo, which are oftencharacterized by high water content and the presence of multiplekinds of ionsCommercial Relationships: Dorota Tarnawska, None; AntoniKocot, None; Maria Jastrzebska, None; Edward Wylegala, None;Alicja Ratuszna, NoneProgram Number: 5296 Poster Board Number: C0215Presentation Time: 2:45 PM - 4:30 PMCorrelation between keratoconus progression and two corneatopometric parameters: the regularity of the pachymetric map(RPM) and the Index of height decentration (IHD)George Asimellis, Ioanna Kontari, A. John Kanellopoulos. Research,LaserVision.gr Eye Institute, Athens, Greece.Purpose: to determine the specificity and sensitivity of keratoconusprogression measured with these two parameters the regularity of thepachymetric map (RPM) and the Index of height decentration (IHD).Methods: Sequential topometric measurements spaced by sixmonths, utilizing the Pentacam device (Scheimpflug imaging) wereconducted in 100 keratoconic eyes. The indices RPM and IHD werecorrelated with keratometry, UDVA, CDVA and minimalpachymetry with 6 years follow-up.Results: Distortion of the RPM and increase of the IHD appeared tobe the first markers of KCN progression in all cases, preceding by anaverage of 18 (± 4.5) months the UDVA, CDVA and keratometricchanges of over 1 diopter.Conclusions: Monitoring RPM and IHD may be a useful earlierdiagnostic tool for ectasia progression and postoperative LASIKstability. It may serve as a new definition of ectasia progression.Commercial Relationships: George Asimellis, None; IoannaKontari, None; A. John Kanellopoulos, Alcon Laboratories, Inc.(C), Avedro (C), Bausch and Lomb (C), Ocular Therapeutix (C)Program Number: 5297 Poster Board Number: C0216Presentation Time: 2:45 PM - 4:30 PMComparison of three-dimensional optical coherence tomographyparameters for early keratoconus diagnosisShinichi Fukuda 1 , Sujin Hoshi 1 , Masahiro Yamanari 2, 3 , SimoneBeheregaray 1 , Takahiro Hiraoka 1 , Yoshiaki Yasuno 2 , TetsuroOshika 1 . 1 Ophthalmology, Tsukuba University, Tsukuba, Japan;2 Computational Optics Group, Tsukuba University, Tsukuba, Japan;3 Tomey Corporation, Nagoya, Japan.Purpose: To investigate changes in keratometric, elevation,topographic, regular and irregular astigmatism, and pachymetricparameters in keratoconus, keratoconus suspect, and normal subjectsusing three-dimensional (3D) corneal and anterior segment opticalcoherence tomography (CAS-OCT), and rotating Scheimpflugcamera combined with Placido topography system (Scheimpflugcamera with topography). Also, to compare discriminative ability ofthese parameters.Methods: Forty eyes of 27 patients with keratoconus, 10 eyes of 10patients with keratoconus suspect, and 77 eye of 77 normal subjects.The keratometric parameters (anterior and posterior steep K, flat K,and Average K), anterior and posterior elevation, topographicparameters, anterior and posterior regular and irregular astigmatism(spherical, asymmetry, regular, and higher order astigmatism), andpachymetric parameters (five pachymetric parameters werecalculated from the region inside the 2-5 mm diameter: Minimum,Minimum-Median, Inferior-Superior, Inferotemporal Superonasal,and the vertical thinnest location of the cornea) were measured using3D CAS-OCT and Scheimpflug camera with topography. The areaunder the receiver-operating curve (AROC) of keratometric,elevation, topographic, regular and irregular astigmatism, andpachymetric parameters.Results: The keratometric parameters, anterior and posteriorelevation, anterior and posterior regular and irregular astigmatism,pachymetric parameters showed good discrimination between normaland keratoconic eyes in both 3D CAS-OCT and Scheimpflug camerawith topography. The AROC of all posterior parameters were higherthan 0.92 and tended to be larger than anterior segment parameters.The AROC value of Inferior-Superior, posterior elevation, andposterior asymmetry were 0.940, 0.909, and 0.906 in earlykeratoconus discrimination analysis.Conclusions: The keratometric parameters, anterior and posteriorelevation, anterior and posterior regular and irregular astigmatism,and pachymetric parameters can effectively discriminate keratoconus.Inferior-Superior, posterior elevation, and posterior asymmetryshowed best predictive accuracy in early keratoconus discriminationanalysis.Commercial Relationships: Shinichi Fukuda, None; Sujin Hoshi,None; Masahiro Yamanari, Tomey Corporation (E); SimoneBeheregaray, None; Takahiro Hiraoka, None; Yoshiaki Yasuno,Topcon Corp. (F), Tomey Corp. (F), Tomey Corp. (P); TetsuroOshika, NoneSupport: Supported in part by Grants-in-Aid 22390320 for ScientificResearch from the Ministry of Education, Culture, Sports, Scienceand Technology, Japan.Program Number: 5298 Poster Board Number: C0217Presentation Time: 2:45 PM - 4:30 PMDecreased corneal sensitivity to chemical and thermal stimuli inkeratoconus patientsLorant Dienes 1 , Kinga Kranitz 1 , Zoltan Z. Nagy 1 , Janos Nemeth 1 , MCarmen Acosta 2 , Juana Gallar 2 , Carlos Belmonte 2 , Illes Kovacs 1 .1 Ophthalmology, Semmelweis University, Budapest, Hungary;2 Instituto de Neurociencias, Univ Miguel Hernandez-CSIC, Alicante,©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.Spain.
ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - CorneaPurpose: To investigate corneal sensitivity to selective mechanical,chemical, and thermal (heat and cold) stimulation in patients withkeratoconus.Methods: Corneal sensitivity to different modalities of stimulus wasdetermined in one randomized eye in 17 patients with mild ormoderate keratoconus (KC) and in 15 healthy subjects (control).Mechanical, chemical, and thermal (hot and cold) thresholds weredetermined at the center of the cornea using a Belmonte's gasesthesiometer. Patients with a history of contact lens wear wereexcluded from the study. All patients completed a questionnaire toassess dry-eye disease symptoms (ocular surface disease index -OSDI).Results: There was no significant difference in age, gender andOSDI between the KC and the control group. Mean corneal thresholdsensitivity values to chemical stimulation (KC: 33.22 ± 0.77 % CO2vs. control: 30.82 ± 0.21 % CO2; p
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