Purchase this article with an account.
K. S. DeLoss, J. E. Walsh, J. P. G. Bergmanson; Current Silicon Hydrogel UVR Blocking Lenses and their Associated Protection Factors. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5659.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Ultraviolet Radiation (UVR) blocking contact lenses provide ocular protection factors (PF) that vary with lens thickness and the nature of the UVR blocking polymer dopant. This study sought to quantify the UVR PF of commercially available silicon hydrogel lenses outdoors and compare this to FDA approved methods for determining PF mathematically. The combination of these measurements provides a comparison between mathematically calculated PF and field based assessment.
Ambient measurements were taken at midday using a portable Solar Light UVA-B radiometer. The detector was adapted to the standard diameter of -3.00D silicon hydrogel lenses that were placed over the radiometer to quantify the UVR blocking capabilities. The UVR blocking silicon hydrogel lenses tested included galyfilcon A, senofilcon A, and enfilcon A. The first UVR blocking hydrogel lens, vasurfilcon, and a non-UVR blocking silicon hydrogel lens, lotrafilcon B, served as a comparison.A fiber optic spectrophotometer front end system was used to measure lens transmittance at the center and periphery from which PF values were calculated using the standard equation. In addition, transmittance spectra were applied to the response curve of the radiometer to predict signal reduction for comparison with the field based measurements.
The contact lens transmittance data showed that there was a significant range of 50% UVR cut-off wavelengths across the UVR blocking contact lenses tested, ranging from 370 nm for enfilcon A to 390 nm for vasurfilcon A, with the non-UVR blocker, lotrafilcon B, transmitting down to 265 nm. In addition, there is a shift of up to 3 nm from center to periphery across UVR blocking test lenses due to the increasing thickness. Field tests of the lenses by the UVA-B radiometer show that the measured percentage decrease in UVR correlates well with the predicted reduction calculated from the lens transmittance data. Measured UVR reduction ranges from 90-98% for the UVR blockers, dropping down to just 13% for the non-blocker. However, the related lens reduction factor from the measured data does not correlate as well with the mathematical determined PF.
The silicon hydrogel lenses showed a wide range of PF for each lens type and an increase from center to periphery. The classic method of determining PF does not always compare well with measured data due to factors such as sensor spectral response and the nature of the solar spectrum.
This PDF is available to Subscribers Only