title: Phototoxic effects of an operating microscope on the ocular surface and tear film.
abstract: OBJECTIVE
  We evaluated light exposure-induced dry eye syndrome by investigating the phototoxic effects of an operating microscope on the ocular surface and tear film in rabbits.
  
  
  METHODS
  Sixty eyes of 30 rabbits were divided into 3 groups based on the intensity of light exposure received from an operating microscope: Control group, no exposure to light; group A, 40,000-lx intensity for 30 minutes; and group B, 100,000-lx intensity for 30 minutes. To evaluate the potential damage to the ocular surface and tear film, Schirmer tests, rose bengal staining, and conjunctival impression cytology were performed before the light exposure and at 1, 3, and 5 days afterward. In addition, the expression of interleukin 1-beta was analyzed in tear samples. The expression of mucin 5AC was evaluated using immunofluorescence staining, and periodic acid-Schiff staining was conducted on conjunctival tissues. Corneal and conjunctival tissues were observed by means of electron microscopy.
  
  
  RESULTS
  Potential damage to the ocular surface and tear film was found in the light-exposed groups as evidenced by decreased aqueous tear production, devitalized corneal and conjunctival epithelial cells, squamous metaplasia of conjunctival epithelial cells, decreased conjunctival goblet cell density, decreased expression of mucin 5AC, ultrastructural cellular damage to corneal and conjunctival tissues, and increased interleukin 1-beta expression in tears. This damage was more noticeable in group B than in group A (P < 0.05).
  
  
  CONCLUSIONS
  Light exposure from an operating microscope had phototoxic effects on the ocular surface and tear film in this in vivo experiment. These changes seemed to intensify as the intensity of the light increased. Therefore, excessive light exposure during ophthalmic procedures could be a pathogenic factor in dry eye syndrome after a surgery is performed.
authors: Department of Ophthalmology, Yeouido St Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: Hyung Bin
authors: HB
authors: Hwang
authors: Hyun Seung
authors: HS
authors: Kim
mesh_terms: D000818:Animals; D003228:Conjunctiva / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects* / Q000648:ultrastructure; D004195:Disease Models, Animal; D019573:Epithelium, Corneal / Q000528:radiation effects* / Q000648:ultrastructure; D020397:Goblet Cells / Q000166:cytology; D053583:Interleukin-1beta / Q000378:metabolism; D008027:Light / Q000009:adverse effects*; D008297:Male; D008853:Microscopy / Q000295:instrumentation*; D008854:Microscopy, Electron; D055271:Mucin 5AC / Q000378:metabolism; D011817:Rabbits; D011832:Radiation Injuries / Q000378:metabolism / Q000473:pathology; D013523:Surgical Equipment / Q000009:adverse effects*; D013666:Tears / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D053583:Interleukin-1beta; D055271:Mucin 5AC