Corneal UV Protective Effects of a Topical Antioxidant Formulation: A Pilot Study on In Vivo Rabbits.

Marisa Palazzo,Francesco Merolla,Germano Guerra,Ciro Caruso,Luigi Pacente,Michele Rinaldi,Lubomir Ondruška,Ciro Costagliola,Francesco Vizzarri,Francesco Vizzarri

doi:10.3390/ijms21155426

Abstract

This study aimed to evaluate the protective effect of a topical antioxidant and ultraviolet (UV) shielding action formulation containing riboflavin and D-α-tocopherol polyethylene glycol succinate (TPGS) vitamin E against corneal UV-induced damage in vivo rabbit eyes. In vivo experiments were performed using male albino rabbits, which were divided into four groups. The control group (CG) did not receive any UV irradiation; the first group (IG) was irradiated with a UV-B−UV-A lamp for 30 min; the second (G30) and third (G60) groups received UV irradiation for 30 and 60 min, respectively, and were topically treated with one drop of the antioxidant and shielding formulation every 15 min, starting one hour before irradiation, until the end of UV exposure. The cornea of the IG group showed irregular thickening, detachment of residual fragments of the Descemet membrane, stromal fluid swelling with consequent collagen fiber disorganization and disruption, and inflammation. The cornea of the G30 group showed edema, a mild thickening of the Descemet membrane without fibrillar collagen disruption and focal discoloration, or inflammation. In the G60 group, the cornea showed a more severe thickening, a more abundant fluid accumulation underneath the Descemet membrane with focal detachment, and no signs of severe tissue alterations, as were recorded in the IG group. Our results demonstrate that topical application of eye drops containing riboflavin and TPGS vitamin E counteracts UV corneal injury in exposed rabbits.

Highlights

Owing to the stratospheric ozone layer depletion, human exposure to ultraviolet (UV) radiation is increasing
A normal rabbit cornea shows an anterior stratified, squamous, non-keratinizing epithelium sitting on a basement membrane; under the epithelium there is a large stromal layer, followed by a membrane that exhibits a homogeneous fine granularity; i.e., Descemet membrane
The endothelium is recognized as a flattened layer of cells attached to the Descemet membrane (Figure 1A)

Summary

Introduction

Owing to the stratospheric ozone layer depletion, human exposure to ultraviolet (UV) radiation is increasing. Ozone is essential for life on Earth because of its ability to absorb UV radiation. UV can be further divided into four bands: UV-vacuum (100–200 nm); UV-A (400–311 nm); UV-B (310–280 nm); and UV-C (280–100 nm). Eye exposure is wavelength-dependent [1,2]. 35% of UV-A rays and approximately 80% of UV-B rays have the greatest potential damage [3,4], despite representing less than 1% of the total radiation reaching the Earth’s surface. UV-C radiation is fully absorbed in the upper atmosphere

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