In situ measurement of spectral changes in the anterior eye following application of ultraviolet-absorbing compounds.

The ocular structures are very sensitive to damage from ultraviolet (UV) radiation, exposure is linked to corneal and conjunctival damage, cataract formation and may also be implicated in the aetiology of age-related macular degeneration. These structures are usually protected by wearing suitable eyeglasses and goggles. An alternative to conventional eyeglasses/goggles is the concept of "liquid sunglasses" which involve the topical application of eye drops that are designed to block harmful UV radiation reaching the sensitive ocular surfaces. The evaluation of such compounds directly applied to the eye surface requires in situ measurements to compare the efficacy of different formulations. A novel ocular spectrometer system has been used to evaluate changes in the transmission of ultraviolet (UV) radiation through the anterior eye following topical application of candidate UV-absorbing formulations. The key feature of the system is the ability to propagate a beam of light tangentially through the anterior eye using a compact, hand-held lens assembly incorporating UV-transmitting optical fibres. A range of formulations containing UV-absorbing compounds were topically applied to ex vivo rabbit eyes. Significant increases in the absorption of the UV spectrum were detected in seven of the eight formulations studied, demonstrating the potential of this measurement technique in the evaluation of formulations developed as potential topical ocular sunscreens.