title: Quantification of the ultraviolet radiation (UVR) field in the human eye in vivo using novel instrumentation and the potential benefits of UVR blocking hydrogel contact lens.
abstract: OBJECTIVE
  Certain degenerative eye conditions occur predominantly nasally, at the limbal region, and are associated with solar ultraviolet radiation (UVR) induced damage. The relative contribution to the in vivo ocular flux of (a) the reflection of UVR incident on the skin of the nose onto the nasal limbus, and (b) the focusing of UVR incident on the temporal side of the cornea onto the nasal limbus were examined.
  
  
  METHODS
  A novel photodiode sensor array was used to measure the UVR field across the eye. In addition, a novel spectrometer set-up was used to measure the spectrum of radiation refracted across the cornea. The efficacy of UVR blocking hydrogel contact lenses in filtering incident UVR was assessed in vivo.
  
  
  RESULTS
  Qualitative and quantitative data indicated an increase nasally of UVR. Photodiode readings showed a net UVR increase from the temporal to the nasal side. Transmission curves showed that most UVR incident on the limbal region is either absorbed by, or transmitted through, the ocular tissues. This radiation is filtered by UVR blocking soft contact lens.
  
  
  CONCLUSIONS
  An increased UVR flux on the nasal side of the eye, due to reflection off the nasal skin, was identified in vivo. Any UVR passing through the cornea is either absorbed by the conjunctiva and/or transmitted through it onto the sclera where it is absorbed. UVR blocking hydrogel contact lenses can eliminate these sources of UVR.
authors.affiliation: School of Physics, Dublin Institute of Technology, Ireland. james.walsh@dit.ie
authors.forename: J E
authors.initials: JE
authors.lastname: Walsh
authors.forename: J P
authors.initials: JP
authors.lastname: Bergmanson
authors.forename: D
authors.initials: D
authors.lastname: Wallace
authors.forename: G
authors.initials: G
authors.lastname: Saldana
authors.forename: H
authors.initials: H
authors.lastname: Dempsey
authors.forename: H
authors.initials: H
authors.lastname: McEvoy
authors.forename: L M
authors.initials: LM
authors.lastname: Collum
mesh_terms: D003263:Contact Lenses, Hydrophilic; D004867:Equipment Design; D005123:Eye / Q000528:radiation effects*; D005128:Eye Diseases / Q000517:prevention & control; D005336:Fiber Optic Technology / Q000379:methods; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000517:prevention & control; D011874:Radiometry / Q000295:instrumentation / Q000379:methods; D012542:Scattering, Radiation; D013057:Spectrum Analysis / Q000379:methods; D014466:Ultraviolet Rays
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate