June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Sub-epithelium curvature: A new method to compare efficacy of surface ablation between manual removal and epi-clear removal of epithelium
Author Affiliations & Notes
  • Rachana C S
    Narayana Nethralaya Foundation, Bangalore, India
  • Mathew Francis
    Narayana Nethralaya Foundation, Bangalore, India
  • Natasha Pahuja
    Refractive and Cornea, Narayana Nethralaya, Bangalore, Karnataka, India
  • RUSHAD SHROFF
    Refractive and Cornea, Narayana Nethralaya, Bangalore, Karnataka, India
  • Rohit Shetty
    Refractive and Cornea, Narayana Nethralaya, Bangalore, Karnataka, India
  • Abhijit Sinha Roy
    Narayana Nethralaya Foundation, Bangalore, India
  • Footnotes
    Commercial Relationships   Rachana C S, None; Mathew Francis, None; Natasha Pahuja, None; RUSHAD SHROFF, None; Rohit Shetty, Narayana Nethralaya (P); Abhijit Sinha Roy, Indo-German Science and Technology centre, Germany (F), Narayana Nethralaya (P), SIBAC Grant (F)
  • Footnotes
    Support  SIBAC grant, Indo-German Science and Technology centre, Germany
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 3526. doi:
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      Rachana C S, Mathew Francis, Natasha Pahuja, RUSHAD SHROFF, Rohit Shetty, Abhijit Sinha Roy; Sub-epithelium curvature: A new method to compare efficacy of surface ablation between manual removal and epi-clear removal of epithelium. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3526.

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

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Abstract

Purpose : To compare post operative change in topography of sub-epithelium surface between manual and Epi-clear removal of epithelium during photorefractive keratectomy(PRK)

Methods : The study included 10 subjects who underwent corneal epithelium removal manually in one eye and using Epi-clear(Orca,Israel) in the other eye before PRK. Subjects were screened for refractive error,topography from Pentacam and optical coherence tomography(OCT) before(pre) and after(post) surgery(between 6-12 weeks). 25 radial scan mode of Pentacam(OCULUS Optikgerate Gmbh,Germany) was used. Corneal imaging was performed by OCT(RTVue-100,Optovue Inc.,CA) which acquired 8 radial scans from 0° to 180° at an A-scan rate of 26,000 lines per second. Since OCT acquired 6 mm diameter scans only, the Pentacam data was also truncated to 6 mm diameter. The anterior corneal surface(ACS) and sub-epithelium surface(SES) edge were detected in radial scans of OCT and axial curvature was computed. Further, keratometry and wavefront aberrations(Zernike analyses upto order 6) were calculated for Pentacam,ACS OCT and SES OCT with refractive index of 1.3375

Results : In manually scraped eyes,changes(pre-to-post change) in keratometry variables were similar to Epi-clear, e.g., flat axis(K1;p=0.6,0.6,0.8),steep axis(K2;p=0.8,0.8,0.8) and maximum keratometry(p=0.7,0.6,0.4) for Pentacam,ACS OCT and SES OCT, respectively. Also, changes in mean keratometry in Pentacam,ACS OCT and SES OCT was similar (p=0.6,0.9,0.5) in Epi-clear and manually scraped eyes. The astigmatism(K1-K2) was similar between Epi-clear and manually scraped eyes [2.2±0.3D and 1.8±0.2D from Pentacam(p=0.7); 1.9±0.5D and 1.7±0.4D from ACS OCT(p=0.1); 2.2±0.5D and 1.7±0.4D from SES OCT(p=0.9)]. Changes in wavefront aberrations of Epi-clear were similar to manually scraped eyes(p>0.05). Figure 1 shows an example of Pentacam topography,ACS OCT and SES OCT topography in two eyes(one with epi-clear and other with manual scraping) pre and post surgery

Conclusions : The topographic changes after Epi-clear and manual removal of epithelium were similar. However, longitudinal follow-up studies are needed to assess the differential effect of Epi-clear surgery on wound healing and haze relative to manual removal of epithelium. This is the first study to quantify changes in surface topography underneath the epithelium non-invasively before and after surgery

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

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