Natsuko Hatsusaka

UV-B exposure to the eye depending on solar altitude

Purpose:To assess the validity of the solar ultraviolet index (UVI) as a determiner of eye risk under different conditions of facial profiles and orientation, and reflected light. Methods:Ocular UV radiation (UVR) exposure was measured as a function of the time of the day (solar altitude) using a two-dummy-type mannequin dosimetry system with embedded UVR (260-310 nm) sensors, in September and November in Kanazawa, Japan, on a motorized sun-tracking mount with one dummy face directed toward the sun and the other away from the sun. Results:A bimodal distribution of UV-B exposure was found in September for the face directed toward the sun, which differed dramatically from the pattern of ambient UVR exposure and measurements taken on the top of the head and those for the eye taken later in the year. Although the overall level was lower, a higher solar altitude is associated with higher UVR exposure in the condition facing away from the sun. Conclusions:The UVI is based on ambient solar radiation on an unobstructed horizontal plane similar to our measures taken on the top of the head, which differed so much from our measures of ocular exposure that UVI as a determiner of eye risk is deemed invalid. The use of the UVI as an indicator for the need for eye protection can be seriously misleading. Doctors should caution patients with regard to this problem, and eye protection may be warranted throughout the year.

Optical simulation for subsurface nanoglistening

Purpose To determine whether subsurface nanoglistening in hydrophobic acrylic intraocular lenses (IOL) diminishes visual performance. Setting Department of Ophthalmology, Kanazawa Medical University, Uchinada, Ishikawa, Japan. Design Experimental study. Methods The effect of subsurface nanoglistenings was simulated using optical design software Lighttools and Code V with the Liou‐Brenann model eye and an acrylic IOL. Peak irradiance of the retina, forward light scattering, and modulation transfer function (MTF) were evaluated. During optical simulation, particle diameters were set at 100 nm, 150 nm, and 200 nm and volume ratios at 0%, 0.05%, 0.1%, 0.2%, 0.5%, and 1.0%. Results Peak irradiance decreased as subsurface nanoglistening volume ratio and particle size increased. At a volume ratio of 0.05%, the peak irradiance of subsurface nanoglistening particles 100 nm, 150 nm, and 200 nm in diameter decreased 0.7%, 1.8%, and 2.9%, respectively, compared with those at volume ratio 0% (no subsurface nanoglistenings). At a volume ratio of 0.1%, the peak irradiance of subsurface nanoglistening particles 100 nm, 150 nm, and 200 nm decreased 1.5%, 3.6%, and 5.7%, respectively. Forward light scattering increased with increased size of subsurface nanoglistening particle and volume ratio. The MTF was not altered by changes in subsurface nanoglistening particle size or volume ratio. Conclusions Subsurface nanoglistenings increased forward scattering slightly and reduced irradiance but significantly diminished retinal image. The effect of subsurface nanoglistenings on visual function in the absence of severe retinal disease was minimal. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.