Spectral transmittance of UV-absorbing soft and rigid gas permeable contact lenses.
Increasing evidence of acute and chronic ocular effects of ultraviolet (UV) radiation has prompted some manufacturers to develop UV-absorbing rigid and soft contact lens materials. Currently, eight different lenses containing UV-absorbing agents are available in Canada. The spectral transmittance of a sample of these UV-absorbing contact lenses was measured in order to determine if all of them provide adequate protection from wavelengths in the UV spectrum. The sample consisted of 1 lens of each type. Cibasoft Ultrabloc; Permaflex UV; Boston RXD and Equalens; Alberta S; FluoroPerm 30, 60, and 92. A Philips single beam spectrophotometer was used. The lens under test was placed in a silica wet cell filled with unpreserved saline. Spectral transmittance was measured at 0.8-nm intervals over the waveband 200 to 800 nm. The results were recorded by a microcomputer interfaced to the spectrophotometer. The repeatability of spectral transmittance measurements of contact lenses using this method varied between 0% and +/- 1.55% of transmission depending on lens material and wavelength studied. The results showed that none of the rigid gas permeable (RGP) lenses, except the Alberta S, transmitted more than 0.1% (the sensitivity limit of the spectrophotometer) up to 380 nm. The Alberta S exhibited transmittance windows in the UV spectrum with peaks at 270 nm (23%) and 318 nm (29%). The Cibasoft Ultrabloc transmitted less than 1% up to 344 nm, whereas the Permaflex UV had a transmittance window in the waveband 240 to 316 nm with a maximum of 17% at 270 nm.(ABSTRACT TRUNCATED AT 250 WORDS)
Quesnel
N M
NM
Ecole d'Optométrie, Université de Montréal, Québec, Canada.
Simonet
P
P
D000042:Absorption; D003263:Contact Lenses, Hydrophilic; D011108:Polymers / Q000528:radiation effects*; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
D011108:Polymers