June 2015
Volume 56, Issue 7
ARVO Annual Meeting Abstract  |   June 2015
Design of Focal UVA Delivery Patterns for Cross-Linking Treatment of Keratoconus
Author Affiliations & Notes
  • Evan A Sherr
    Avedro, Inc, Waltham, MA
  • Satish V Herekar
    Avedro, Inc, Waltham, MA
  • Grace Lytle
    Avedro, Inc, Waltham, MA
  • Marc D Friedman
    Avedro, Inc, Waltham, MA
  • William J Dupps
    Avedro, Inc, Waltham, MA
  • Anders Behndig
    Avedro, Inc, Waltham, MA
  • David Muller
    Avedro, Inc, Waltham, MA
  • Footnotes
    Commercial Relationships Evan Sherr, Avedro (E); Satish Herekar, Avedro (E); Grace Lytle, Avedro (E); Marc Friedman, Avedro (E); William Dupps, Avedro (C); Anders Behndig, Avedro (C); David Muller, Avedro (E)
  • Footnotes
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Investigative Ophthalmology & Visual Science June 2015, Vol.56, 3000. doi:
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      Evan A Sherr, Satish V Herekar, Grace Lytle, Marc D Friedman, William J Dupps, Anders Behndig, David Muller; Design of Focal UVA Delivery Patterns for Cross-Linking Treatment of Keratoconus. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3000.

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

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Purpose: Pan-corneal Cross-Linking (CXL) is used to stabilize and reduce corneal curvature (Kmax) in Keratoconus (KC). Development of patterned UV systems provides an opportunity to provide focal treatment with the intention of improving vision. Theoretical Finite Element Models (FEM) of crosslinking in KC cornea suggest focal treatment may improve central corneal symmetry. This study retrospectively evaluated focal crosslinking in KC patients to evaluate the potential of focal CXL to improve visual function.

Methods: Six subjects presenting with KC exhibiting inferior Kmax received focal CXL treatment, based on pre-treatment topography, using KXL II (Avedro, Inc.) custom beam patterning system (PiXL). Treatment consisted of stepped, arc-shaped UV exposures, applied over the area of corneal steepening on Sagittal Curvature map, in doses of 5.4 J/cm2 (K=43-47.5D), 10 J/cm2 (K=48-51 D), 15 J/cm2 (K=51.5+ D) at 30 mW/cm2, pulsed 1:1 treatment. Areas avoided the central 2-mm visual field.<br /> Subjects were evaluated at 6 months follow-up. Sagittal and Tangential curvature, and Kmax were compared to baseline. Location of treatment was compared to location of maximum corneal thinning and posterior elevation.

Results: At 6 months, subject’s central topographies were more symmetric, exhibiting inferior flattening and superior steepening on Sagittal and Tangential maps, as predicted by FEM Models. On average there was no significant progression of corneal steepening over the follow-up period, nor significant change in Kmax. For most subjects, area of maximum corneal thinning and posterior elevation were not enclosed by the treatment area.

Conclusions: As predicted by FEM, focal treatment of inferior steepening results in localized flattening of the treated area with concomitant steepening of adjacent untreated cornea, resulting in greater central symmetry. These preliminary results suggest that focal treatment may provide greater visual improvement and improved contact lens tolerance over pan-corneal cross-linking. Treatment may be optimized by alternative selection of landmarks and is a subject of additional research.


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