A transparent PVA-based polymer sunscreen protects retinal tissue from ultraviolet damage

Ultraviolet (UV) light causes many eye diseases. Wearing sunglasses blocks <50% UV light from entering eyes. Skin sunscreens are banned for eye use due to irritation and safety concerns. Few sunscreens can be used in the eye to block UV light without compromising the eye functions. Herein, we modified poly(vinyl alcohol) (PVA), the active ingredient in commercial artificial tears, using naturally extracted aldehydes through Hantzsch's reaction and obtained a PVA-syringaldehyde derivative that has a high sun protection factor (SPF 80), excellent UV resistance (>99%) and high transparency (84%) at 1 wt% in water, and a long half-life with little acute irritation and long-term safety when applied to female mouse eyes. Zebrafish protected by this polymer maintained healthy eye tissues and vision-guided behaviors after UV exposure. Polymer treatment on mice eyes effectively protected the retina from UV-induced damage, suggesting its potential as an eye sunscreen.