Light transmission and ultraviolet protection of contact lenses under artificial illumination.

PURPOSE: To determine the spectral transmission of contact lenses (CLs), with and without an ultraviolet (UV) filter to evaluate their capacity for protection under UV radiation from artificial illumination (incandescent, fluorescent, xenon (Xe) lamps, or white LEDs (light-emitting diode)). METHODS: The transmission curves of nine soft CLs were obtained by using a PerkinElmer Lambda 35 UV-vis spectrophotometer. A CIE standard was used for the emission spectra of incandescent and fluorescent lamps, and Xe lamps and white LEDs were measured by using an International Light Technologies ILT-950 spectroradiometer. RESULTS: Five of the nine soft CLs analysed state that they incorporate UV filters, but the other four do not specify anything in this regard. The spectral transmission of all the CLs studied is excellent in the visible region. The CLs with UV filters filter out this radiation more or less effectively. Xe lamps emit a part in the UV region. Incandescent, fluorescent and white LEDs do not emit at all in the UV. CONCLUSIONS: Incorporating UV filters is important when the illumination is from a Xe lamp since this light source emits in the UV region. This, however, does not occur with incandescent and fluorescent lamps or white LEDs. The CLs that do incorporate UV filters meet all the standard requirements that the U.S. FDA (Food and Drug Administration) has for UV-blocking CLs Class II (OcularScience, CooperVision and Neolens), and AcuvueMoist and HydronActifresh400 even comply with the stricter Class I. The CLs without UV filters let UVA, UVB and even some UVC through.

Correlation between optics quality of multifocal intraocular lenses and visual acuity: tolerance to modulation transfer function decay.

PURPOSE: To study the relationship between the optics quality of multifocal intraocular lenses (IOLs) and distance-corrected near, intermediate, and distance visual acuity to determine the degree to which optics quality must change to produce a significant difference in visual acuity. SETTING: Fundación Oftalmológica del Mediterráneo, Valencia, Spain. METHODS: Monocular distance-corrected visual acuity (decimal and logMAR) was measured at 4 m, 70 cm, and 30 cm under photopic and mesopic conditions in eyes with 1 of 3 multifocal IOL models. Visual acuity versus the "average modulation" of the IOL was assessed. RESULTS: The pupil diameter and patient age were similar between the 3 IOL groups (20 eyes each). A difference in average modulation (ie, optics quality) up to 15% did not produce significant differences in mean visual acuity between 2 groups; however, there was a significant difference in mean visual acuity between 2 groups when the average modulation values differed by at least 25%. The slope of the linear correlation between visual acuity and average modulation was 0.018 (r(2) = 0.91) under photopic conditions and 0.024 (r(2) = 0.089) under mesopic conditions. CONCLUSIONS: There was a strong linear correlation between IOL optics quality and visual acuity with distance correction under photopic conditions with a pupil of approximately 3.5 mm in a cohort in which the patient age was controlled. The correlation was similar under mesopic conditions. The eye's tolerance to modulation transfer function decay was approximately 15% of the average modulation value.