Effectiveness of eye drops protective against ultraviolet radiation.
BACKGROUND
To test the effectiveness of commercially available ultraviolet (UV)-protective eye drops (8-hydroxy-1-methylchinolinium methylsulphate) which are recommended for protection against both solar and artificial UV radiation.


METHODS
The spectral transmission in the wavelength range from 250 to 500 nm was investigated in 1-nm steps using a high-resolution double monochromator with holographic gratings of 2,400 lines/mm and a 1,000-watt halogen lamp as light source. The transmission spectrum was measured for different values of the layer thickness.


RESULTS
The transmission of a liquid layer of about 10 microns, which corresponds to the thickness of the human tear film, shows a cut-off at 290 nm with a transmission of about 25-50% at shorter wavelengths. For wavelengths longer than 290 nm the transmission is higher than 90%. The threshold time ratio for keratitis formation with and without eye drops is above 0.93 considering solar radiation on the earth's surface and above 0.65 considering radiation from arc-welding, respectively.


CONCLUSIONS
The transmission spectrum of the eye drops under realistic conditions does not show a protective effect against solar UV radiation. However, there exists reduction of UVC radiation in the spectral range typical of artificial UV sources such as arc-welding. We cannot recommend the application of these eye drops as an UV-protective aid against eye damage by solar UV radiation.
Abteilungen für Augenheilkunde, Landeshauptstadt St. Pölten, Austria. daxer@pap.univie.ac.at
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Daxer
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Blumthaler
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Schreder
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Ettl
D005123:Eye / Q000528:radiation effects; D005131:Eye Injuries / Q000517:prevention & control; D006801:Humans; D008698:Mesylates / Q000737:chemistry* / Q000494:pharmacology; D009883:Ophthalmic Solutions / Q000737:chemistry* / Q000494:pharmacology; D011832:Radiation Injuries / Q000517:prevention & control*; D011837:Radiation-Protective Agents / Q000737:chemistry* / Q000494:pharmacology; D013057:Spectrum Analysis; D014466:Ultraviolet Rays
C114629:8-hydroxy-1-methylchinolinium methylsulfate; D008698:Mesylates; D009883:Ophthalmic Solutions; D011837:Radiation-Protective Agents