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JG Bergmanson, A Gaume, J Walsh, L Moore, H Sheriff; In vivo quantification of the ultraviolet Radiation field AT the human eye USING Novel instrumentation . Invest. Ophthalmol. Vis. Sci. 2002;43(13):130.
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Purpose:Some degenerative eye conditions occur predominantly nasally, at the limbal region. It has been proposed that patho-physiological changes in these conditions are associated with solar ultraviolet radiation (UVR) induced damage to ocular tissues. Two mechanisms for the nasal-temporal bias of UVR have been expounded: UVR incident on the skin of the nose is reflected onto the nasal limbus and UVR incident on the temporal side of the cornea is focussed onto the nasal limbus by tangential refraction through the cornea and anterior chamber. The present study seeks to absolutely quantify the level of the former of these mechanisms on the in vivo ocular UVR flux. Methods:A second generation of novel photodiode sensor arrays for measuring the levels of the UVR field across the in vivo eye was designed and tested. The new system has three UVR, solar blind, sensitive sensors that allowed UVR readings to be taken in the field under strong solar irradiation. The three sensors, situated near the lateral limbus, the pupil and the nasal limbus, allowed the absolute UVR levels across the exposed ocular surface to be quantified. In addition, the effects of surface albedo on the in vivo ocular UVR light field were tested. Results:Quantitative data from the sensor array showed the absolute UVR level incident on the human eye for a range of solar viewing angles. The relative nasal limbal bias due to surface type and landscape features was also assessed, illustrating the complexity of typical natural UVR fields. Conclusion:The UV-visible flux across the eye, with a nasal-lateral bias due to reflection off the nasal skin has previously been established in vivo using a solar simulating light box. The high number of measurement permutations introduced in the natural UVR environment forms the basis for a rigorously planned set of future observations and sensor designs that will quantify the true ocular light field experienced in vivo. The radiation levels measured endorse the wearing of UVR blocking hydrogel contact lenses as means to afford ocular protection, regardless of solar viewing angle and surface type.
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