Three-tier testing approach for optimal ocular tolerance sunscreen

Cutan Ocul Toxicol. 2019 Sep;38(3):212-220. doi: 10.1080/15569527.2019.1601106. Epub 2019 May 7.

Abstract

Background: Poor ocular tolerance of sunscreens is partially responsible for poor compliance in use of sunscreens. A three-tiered approach for the testing of ocular tolerance for such products is described that includes an in vitro test for ocular irritation, an in vitro test for the activation of pain receptors, and finally a clinical study involving ocular instillation of the product under controlled conditions followed by ophthalmologic and subjective self-evaluation on a graded scale. We report the results for a new water-based facial sunscreen (SCFW) with very good ocular tolerance. Methods: The ocular irritation potential of SCFW was determined using the EpiOcular™ human cell construct which constituted the first-tier testing. Briefly, the tissues were exposed to SCFW and appropriate positive and negative controls for 15 minutes to 24 hours. After treatment, the tissues were rinsed and cytotoxicity determined. The calculated ET50 value (time at which relative viability decreased 50%) was then used to determine the ocular irritation potential. In the second-tier testing, the sting potential of SCFW was determined by employing the NociOcular assay that measures the activation of TRPV1 (transient receptor potential cation channel subfamily V member 1) specific receptors linked to pain sensation in a neuronal model with over-expression of functional TRPV1 channels. Finally, as the third-tier testing, SCFW was tested in a clinical study with instillation of product into the ocular cul-de-sac and ocular irritation was evaluated after 30 seconds, 15 minutes, and 60 minutes by an ophthalmologist. Participating subjects were also asked to score sensation on a scale of 0 to 3 from slight prickliness to severe stinging. Assay control reference product with known good ocular tolerability (10% baby shampoo) was concurrently tested. Results: In the in vitro topical application assay using the EpiOcular™ construct, no significant cytotoxicity was observed in the tissues exposed to SCFW, indicating minimal ocular irritation potential. In the in vitro NociOcular assay, the cells exposed to the prepared dilutions of SCFW showed minimal TRPV1 specific activity, indicating minimal ocular sting potential. In the in vivo study, no statistically significant differences were found in terms of subjective or objective eye irritation assessment between SCFW and 10% baby shampoo. Conclusion: SCFW showed negligible ocular irritation potential in tier 1, minimal potential to activate pain receptors in tier 2, and good ocular tolerability that was comparable to 10% baby shampoo in tier 3 testing. The results suggest that SCFW has good eye tolerance and that the tiered approach can be used to evaluate facial sunscreens for ocular tolerability.

Keywords: EpiOcular™; Sunscreen; TRPV1 receptors; eye stinging potential; instillation; ocular tolerability.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Cell Line, Tumor
  • Double-Blind Method
  • Eye / drug effects*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Sunscreening Agents / toxicity*
  • TRPV Cation Channels / genetics
  • TRPV Cation Channels / metabolism
  • Toxicity Tests / methods

Substances

  • Sunscreening Agents
  • TRPV Cation Channels
  • Trpv1 protein, rat