Purchase this article with an account.
Emiliano Teran, Pablo De Gracia, Efrain Romo-Garcia, Jesus Ortega; UV protection of contact lenses under outdoor light environments: beach, snow and city. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3891.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To calculate the elevation of the threshold of safe exposure times occurring when subjects wear contact lenses in three outdoor environments: cities, beaches, and snowed mountains.
Environmental irradiance reaching the naked eye was calculated using a solar spectral model for direct and diffuse irradiance. Three scenarios were considered for our calculations: city (Los Angeles, CA), beach (Miami, FL), and snowed mountain (Aspen, CO) at noon in winter. Effective irradiance was achieved through the integration by wavelength of the environmental irradiance weighted by the relative spectral effectiveness times the lenses transmittance. This method was applied to: (1) Calculate UV radiation levels on naked eye, and (2) Calculate UV radiation levels when using contact lenses. These calculations were performed for four soft contact lenses (Cooper Vision) with a power of +3.00D and UV protection: “ClearSight 1-Day”, “Clariti 1 day”, “Avaira Vitality” and “MyDay”. Transmission curves for these lenses were measured with a NanoDrop One UV-VIS spectrophotometer (Thermo Scientific). Finally the maximum exposure times for conditions 1 and 2 were obtained dividing the radiant exposure threshold by the retinal effective irradiance without (1) and with (2) lenses in the three light environments.
(1) Safe exposure times for naked eyes were found to be: City of LA (10 min), The beach of Miami (7min), and Aspen Mountains (9 min). It should be noted that UV radiation in the city, the beach, or the mountain are fairly similar. (2) Safe exposure times increases significantly when using contact lenses in all conditions, up by a factor of x 834 times in the best scenario (using “MyDay” on LA) and by a factor of x 38 on the worst improvement found (Clear Sight 1-Day on Miami), see table 1.
All the contact lenses tested are able to protect the integrity of the internal structures of the eye for a normal day of activity and normal UV levels on the three locations included on the study. The minimum protection offered is 6.4 hours on the beach. It is worth remembering that the lenses only cover the central region of the eye. For instance, the conjunctiva and the facial skin around the eye are still exposed to normal levels of UV radiation if glasses, umbrellas, or hats are not used.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Table 1. Maximum time exposures obtained with and without contact lentes with UV protecion.
This PDF is available to Subscribers Only