Analysis of Corneal Biomechanical Properties in Keratoconus Using Ocular Response Analyzer Hyuck Jin Choi, Joo Youn Oh, Won Ryang Wee, Mee Kum Kim, Ji Won Kwon, Sang Mok Lee, MD, Jin Seok Choi, MD Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea Seoul Artificial Eye Center, Seoul National Univerisity Hospital Clinical Research Institute, Seoul, Korea
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Analysis of Corneal Biomechanical Properties in Keratoconus Using Ocular Response Analyzer
Analysis of Corneal Biomechanical Properties in Keratoconus Using Ocular Response Analyzer. Hyuck Jin Choi, Joo Youn Oh, Won Ryang Wee, Mee Kum Kim, Ji Won Kwon, Sang Mok Lee, MD, Jin Seok Choi, MD. Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea - PowerPoint PPT Presentation
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Analysis of Corneal Biomechanical Properties in Keratoconus Using
Ocular Response Analyzer
Hyuck Jin Choi, Joo Youn Oh, Won Ryang Wee, Mee Kum Kim,
Ji Won Kwon, Sang Mok Lee, MD, Jin Seok Choi, MD
Department of Ophthalmology, Seoul National University College of Medicine, Seoul, KoreaSeoul Artificial Eye Center, Seoul National Univerisity Hospital Clinical Research Institute, Seoul, Korea
Financial Disclosure
The authors of this poster have no financial
interest in the subject matters.
Introduction
Biomechanical Properties of Cornea•Hysteresis
•A property of physical systems that do not instantly follow the forces applied to them, but react slowly, or do not return completely to theior original state•Etymology: ‘ late, fall short’ in ancient Greek
•Corneal Hysteresis (CH)•The the difference between the inward (P1) and outward (P2) pressure values obtained during the dynamic bi-directional applanation process employed in the Ocular Response Analyzer, as a result of viscous damping in the cornea.•P1 – P2
•Corneal Resistance Factor (CRF)•the overall resistance of the cornea, including both the viscous and elastic properties (total visco-elasticity)•P1 – 0.7 x P2
Ocular Response Analyzer
Introduction
Biomechanical Properties of Cornea•Corneal-compensated intraocular pressure (IOPcc)
•Less affected by corneal properties than other tonometry•P2 – 0.43 x P1
•Goldmann-correlated intraocular pressure (IOPg)•the overall resistance of the cornea, including both the viscous and elastic properties (total visco-elasticity)•P1 – 0.7 x P2
DiscussionCorneal biomechanical changes in keratoconus
• B oth CH and CRF in keratoconus ⇒ lo w er than normal control• CRF decreased more than CH.• As corneal thicknessdecreases, biomechanical stability decreases
Combined parameters in keratoconus•IOPcc-g and IOPcc/g
• If IOPcc-g or IOPcc/g is high, there is corneal biomechanical change more than normal condition.• GAT can be underestimated in keratoconus.
Correlation Analysis with ORB Scan• CH-CRF, CH/CRF
• CCT w as negatively correlated• As w ell as CCT, simK value and irregular astigmatism of 3mm and 5mm were also positively correlated.
• IOPcc-g, IOPcc/g• Only CCT w as negatively correlated
DiscussionAbout keratoconus suspect
• Possibility to detect early keratoconus change or progression.
Limitations• Cross-sectional study
• Difficult to generalize into the change in subject
Suggestions for future studies• Study to find the risk factors of post-LASIK ectasia with various ORA parameters.
ConclusionsThe corneal biomechanical parameters and their combined parameters measured using Ocular Response Analyzer were correlated with topographic parameters. So there is a possibility to put the biomechanical parameters to practical use in detecting and monitor keratoconus.