title: 1090 nm infrared radiation at close to threshold dose induces cataract with a time delay.
abstract: OBJECTIVE
  To investigate whether infrared radiation (IRR)-induced cataract is instant or is associated with a time delay between the exposure and the onset of lens light scattering after an exposure to just above threshold dose.
  
  
  METHODS
  Six-weeks-old albino Sprague-Dawley female rats were unilaterally exposed to 197 W/cm2 IRR at 1090 nm within the dilated pupil. In the first experiment, the animals were exposed with four exposure times of 5, 8, 13 and 20 second, respectively. At 24 hr after exposure, the light scattering in both exposed and contralateral not exposed lenses was measured. Based on the first experiment, four postexposure time groups were exposed unilaterally to 1090 nm IRR of 197 W/cm2 for 8 second. At 6, 18, 55 and 168 hr after exposure, the light scattering in both lenses was measured.
  
  
  RESULTS
  A 197 W/cm2 IRR-induced light scattering in the lens with exposures of at least 8 second. Further, after exposure to IRR of 197 W/cm2 for 8 second, the light-scattering increase in the lens was delayed approximately 16 hr after the exposure.
  
  
  CONCLUSIONS
  There is a time delay between the exposure and the onset of cataract after exposure to close to threshold dose implicating that either near IRR cataract is photochemical or there is a time delay in the biological expression of thermally induced damage.
authors.affiliation: Gullstrand lab, Ophthalmology, Department of Neuroscience, Uppsala University, Uppsala, Sweden.
authors.forename: Zhaohua
authors.initials: Z
authors.lastname: Yu
authors.forename: Karl
authors.initials: K
authors.lastname: Schulmeister
authors.forename: Nooshin
authors.initials: N
authors.lastname: Talebizadeh
authors.forename: Martin
authors.initials: M
authors.lastname: Kronschläger
authors.forename: Per G
authors.initials: PG
authors.lastname: Söderberg
mesh_terms: D000818:Animals; D002386:Cataract / Q000209:etiology* / Q000473:pathology; D004307:Dose-Response Relationship, Radiation; D005260:Female; D007259:Infrared Rays / Q000009:adverse effects*; D007908:Lens, Crystalline / Q000528:radiation effects*; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000209:etiology* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012542:Scattering, Radiation; D013997:Time Factors
keywords: forward light scattering; infrared radiation; lens; photochemical; thermal