July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
The Effect of NaI on Stromal Loading, Distribution and Degradation of CXLO Corneal Strengthening Solution after Topical Application and UVA Exposure in New Zealand White Rabbits
Author Affiliations & Notes
  • Glenwood G Gum
    Absorption Systems, San Diego, California, United States
  • Roy Rubinfeld
    CXL Ophthalmics, LLC, Washington, DC, District of Columbia, United States
  • Edward Parsons
    CXL Ophthalmics, LLC, Washington, DC, District of Columbia, United States
  • Footnotes
    Commercial Relationships   Glenwood Gum, None; Roy Rubinfeld, CXl Ophthalmics, LLC (P); Edward Parsons, CXL ophthalmics, LLC (C)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 4657. doi:
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      Glenwood G Gum, Roy Rubinfeld, Edward Parsons; The Effect of NaI on Stromal Loading, Distribution and Degradation of CXLO Corneal Strengthening Solution after Topical Application and UVA Exposure in New Zealand White Rabbits. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4657.

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

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Abstract

Purpose : To evaluate effect of NaI on the persistence of Ribostat™ (riboflavin + sodium iodide, CXL Ophthalmics) using recommended clinical procedures[1] for corneal collagen cross-linking during application and UVA exposure in New Zealand White rabbits.

Methods : To determine the optimal riboflavin loading time, four rabbits were dosed with Ribostat (with NaI) and an otherwise identical solution without NaI in contralateral eyes using the Epi-Prep™ and Ribostat loading system. Slit lamp photos were captured at baseline, 2.5, 4.5, 6.5, 8.5, 10.5, and 12.5 min. Slit lamp photos were scored using a previously calibrated 0 to 5 point scale of riboflavin fluorescence intensity[2].

A loading time of 12.0 min. was selected. Sixteen additional rabbits were randomized to receive the CXLO solution with NaI and without NaI in alternate eyes using the CXLO system. Eyes were then exposed to UVA for 30 min. at 4mW, with a 15 sec. on/15 sec. off cycle. Slit lamp photos were taken at 0, 10, 15, 20, 25, and 30 min. post-riboflavin loading. Slit lamp photos were masked and evaluated for ocular clinical exams and riboflavin intensity score. Riboflavin scores were compared using a Wilcoxon Ranked-Sum test (p<0.05).

Results : Immediately after loading the solution containing NaI had a greater riboflavin score, and maintained significantly higher (p< 0.0094 to 0.028) riboflavin loading/grade from 15 through 30 min. during UVA light exposure. The solution without NaI had a higher degradation rate when exposed to UVA light. The baseline difference and differential rates of degradation during UVA exposure may imply separate riboflavin penetration and photoprotection effects by which NaI improves the concentration of active riboflavin in corneal stroma. Only minor conjunctival congestion was noted post riboflavin loading with NaI or without NaI.

Conclusions : Ribostat solution with NaI provides a significantly higher riboflavin concentration in the corneal stroma. In the presence of UVA light, NaI appears to reduce photo-degradation of riboflavin over a clinically-relevant course of UVA exposure.

[1] Stulting et al. J Cataract Refract Surg. 2018 Nov;44(11):1363-1370.
[2] Rubinfeld et al. J Cataract Refract Surg. 2018 Feb;44(2):237-242.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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