June 2013
Volume 54, Issue 15
ARVO Annual Meeting Abstract  |   June 2013
Novel Corneal Biomechanical Parameters in Myopes vs Emmetropes
Author Affiliations & Notes
  • Rachel Lee
    Stanford University School of Medicine, Stanford, CA
  • Robert Chang
    Stanford University School of Medicine, Stanford, CA
  • Ian Wong
    Hong Kong University School of Medicine, Hong Kong, Hong Kong
  • Jimmy Lai
    Hong Kong University School of Medicine, Hong Kong, Hong Kong
  • Jacky Lee
    Hong Kong University School of Medicine, Hong Kong, Hong Kong
  • Kuldev Singh
    Stanford University School of Medicine, Stanford, CA
  • Footnotes
    Commercial Relationships Rachel Lee, None; Robert Chang, None; Ian Wong, bayer (C); Jimmy Lai, Pfizer (R), Allergan (R), Alcon (R); Jacky Lee, Allergan (F), Alcon (F), AMO (F); Kuldev Singh, Alcon (C), Allergan (C), Santen (C), Bausch and Lomb (C), Transcend (C), Ivantis (C), Sucampo (C), iScience (C)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 1638. doi:
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    • Get Citation

      Rachel Lee, Robert Chang, Ian Wong, Jimmy Lai, Jacky Lee, Kuldev Singh; Novel Corneal Biomechanical Parameters in Myopes vs Emmetropes. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1638.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: While population-based studies have shown that myopia is a risk factor for glaucoma, the underlying basis of this correlation is unknown. We aim to identify novel corneal biomechanical parameters that differentiate myopic from normal eyes using a novel technology.

Methods: This prospective, cross-sectional study of 80 subjects with varying degrees of myopia and 62 emmetropies was conducted at Queen Mary Hospital in Hong Kong. The Corvis ST device (Oculus, Wetzlar, Germany), which couples a pneumotonometer with a high speed Scheimpflug camera, was used to measure IOP, CCT, and new biomechanical parameters including corneal deformation amplitude, inward and outward applanation velocity, and highest concavity peak-to-peak distance. The right eye of all subjects and controls underwent Corvis analysis. Myopes were subsequently categorized as being high (vision correction at least -9.0 D), moderate (-6.0 D to -9.0 D), or mild (-3.0 D to -6.0 D) myopes. Exclusion criteria included known corneal disease, intraocular surgery within three months preceding the study, or prior history of refractive surgery.

Results: Significant findings included differences in outward applanation velocity (myope: -0.38±0.08 m/s; control: -0.33±0.05 m/s; P=3.2E-5) and peak-to-peak distance (myope: 2.43±0.24 mm; control: 2.32±0.20 mm; P=3.6E-3). Interestingly, high (n=19), but not moderate (n=25) or low (n=36), myopes exhibited statistically significant differences in these two corneal biomechanical parameters as compared to controls. There was moderate correlation between IOP, CCT and visual acuity with outward applanation velocity (R=0.43; 0.34; 0.50, respectively), and with peak-to-peak distance (R=0.40; 0.15; 0.32, respectively). No correlation was found between age and outward applanation velocity (R=0.060) or peak-to-peak distance (R=0.039). Average IOP in myopes and emmetropes were 15.2±2.2 mm Hg and 14.9±2.1 mm Hg, respectively (P=4.0 E-1); average CCT in myopes and emmetropes was 554±34 μm and 554±39 μm, respectively (P=9.5 E-1).

Conclusions: Myopes had a greater mean outward applanation velocity and greater peak-to-peak distance at highest concavity than emmetropic controls. In particular, high myopes demonstrated a corneal biomechanical profile distinct from that of emmetropes. Increased corneal deformability in high myopes, also found in glaucoma patients from another study, may indicate a relationship between high myopia and glaucoma.

Keywords: 605 myopia • 479 cornea: clinical science  

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