title: Measuring ultraviolet-visible light transmission of intraocular lenses: double-beam mode versus integrating-sphere mode.
abstract: This study compared integrating-sphere and double-beam methodologies for measuring the ultraviolet/visible transmission of intraocular lenses (IOLs). Transmission spectra of control IOLs and clinically explanted IOLs were measured with an optical spectrophotometer in two optical configurations: single-beam mode with integrating sphere detector and double-beam mode with photodiode detector. Effects of temperature and surface light scattering on transmittance were measured. Effects of lens power were measured and were modeled with ray-tracing software. Results indicated that transmission was consistent over a range of IOL powers when measured with the integrating-sphere configuration, but transmission gradually decreased with increasing IOL power (in a wavelength-dependent fashion) when measured with the double-beam configuration. Ray tracing indicated that the power-dependent loss in transmission was partially due to higher-powered IOLs spreading the light beam outside of the detector area. IOLs with surface light scattering had transmission spectra that differed between double-beam and integrating-sphere configurations in a power-dependent fashion. Temperature (ambient or physiological 35°C) did not affect transmission in the integrating-sphere configuration. Overall, results indicated that double-beam spectrophotometers may be useful for measuring transmittance of low-power IOLs, but an integrating-sphere configuration should be used to obtain accurate measurements of transmittance of higher-power IOLs.
authors.affiliation: Alcon Research, Ltd., 6201 South Freeway, Fort Worth, Texas 76134-2099, USA. ali.akinay@alconlabs.com
authors.forename: Ali
authors.initials: A
authors.lastname: Akinay
authors.forename: Marcia D
authors.initials: MD
authors.lastname: Ong
authors.forename: Myoung
authors.initials: M
authors.lastname: Choi
authors.forename: Mutlu
authors.initials: M
authors.lastname: Karakelle
mesh_terms: D007910:Lenses, Intraocular; D008027:Light; D012542:Scattering, Radiation; D013053:Spectrophotometry / Q000295:instrumentation* / Q000379:methods; D013696:Temperature; D014466:Ultraviolet Rays