July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Comparison of corneal biomechanical properties measured by Ultra-High-Speed Scheimpflug camera between myopic and emmetropic eyes
Author Affiliations & Notes
  • Aratchaporn Tubtimthong
    Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
  • Sunee Chansangpetch
    Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
    Department of Ophthalmology, University of California, San Francisco Medical School, San Francisco, California, United States
  • Nitee Ratprasatporn
    Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
  • Prin Rojanapongpun
    Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
  • Shan C Lin
    Department of Ophthalmology, University of California, San Francisco Medical School, San Francisco, California, United States
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 1170. doi:
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      Aratchaporn Tubtimthong, Sunee Chansangpetch, Nitee Ratprasatporn, Prin Rojanapongpun, Shan C Lin; Comparison of corneal biomechanical properties measured by Ultra-High-Speed Scheimpflug camera between myopic and emmetropic eyes. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1170.

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

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Abstract

Purpose : Previous studies on corneal characteristics in myopes have yielded conflicting results. The Scheimpflug-based camera (Corvis ST) has the advantage of providing precise corneal biomechanical measurements from the corneal deformation-reformation cycle. The purpose of this study is to evaluate the effect of myopia on corneal biomechanical properties.

Methods : In this cross-sectional study, we recruited subjects aged greater than 40 years who had no history of ocular or corneal pathology. Subjects with previous laser treatment or ocular surgery were excluded. Myopia was defined as spherical equivalence (SE) ≥ -4.00 diopters (D) and axial length (AL) ≥ 26 mm while emmetropia was defined as SE between -0.50 and +0.50 D and AL < 26 mm. Seven corneal biomechanical parameters including corneal deformation amplitude (CDA), inward/outward corneal applanation length (ICA, OCA), inward/outward corneal velocity (ICV, OCV), peak distance (PD) and radius were measured using the Corvis ST. Linear mixed-effects model analysis was performed to compare parameters between the two groups.

Results : Fifty-five myopic eyes and 129 emmetropic eyes were recruited. The studied subjects were comprised of 45 (40 %) male and 66 (60%) female. Mean age (SD) was 61.14 (9.49) years. Median SE (IQR) and mean (SD) AL were −7.88 (-9 to -5.37) D and 26.84 (1.46) in the myopes, and -0.13 (-0.5 to 0.56) and 23.47 (0.77) in the emmetropes, respectively. Results of corneal biomechanical parameters are shown in Table 1. Myopic eyes had significantly lower OCV than the emmetropic group (p=0.02). Linear mixed-effects regression analysis after adjustment for age, gender, intraocular pressure, central corneal thickness and laterality demonstrated significantly higher CDA (β=0.059, p<0.001), lower OCV (β=-0.063, p<0.001), and lower radius (β=-0.336, p=0.02) in the myopic group.

Conclusions : Myopic eyes had significantly higher CDA, lower OCV and lower radius than emmetropic eyes. Given that the minus symbol of OCV represents outward direction of the cornea while regaining its original shape, greater absolute value of OCV in myopes indicates that myopic eyes recoil back more quickly. Our results may suggest that myopic eyes have a reduced corneal stiffness which could lead to more instability and less resistance to stress than emmetropic eyes.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Table 1 Comparison of corneal biomechanical properties

Table 1 Comparison of corneal biomechanical properties

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