title: Effect of Titanium Dioxide Nanoparticle Exposure on the Ocular Surface: An Animal Study.
abstract: To evaluate the effect of titanium dioxide (TiO2) nanoparticle exposure on the ocular surface.
  
  
  
  Eighty eyes of 40 rabbits were used. The TiO2-1D group (n = 20) received a single instillation of TiO2 in the right eye. The TiO2-4D group (n = 20) received a TiO2 instillation in the right eye once a day for four days. The 40 untreated left eyes were used as controls. Ocular surface staining (n = 5 for each group) was performed with rose bengal dye, tear secretion (n = 5) was measured using the phenol red thread test, lactic dehydrogenase (LDH) activity (n = 5) and MUC5AC levels (n = 5) were measured in tears, and the area of the conjunctival goblet cells (n = 5) was measured through impression cytology and scanning electron microscopy 24 hours after the last TiO2 instillation.
  
  
  
  Ocular surface staining was increased but the tear secretion was not changed after TiO2 exposure. The TiO2-1D (1.39 OD) and TiO2-4D groups (0.58 OD) had higher median tear LDH activity than the control groups (0.57 OD and 0.29 OD, respectively). Although the median tear MUC5AC level in the TiO2-1D group (92.7 ng/ml) was higher than that of control 1 group (37.4 ng/ml), there was no significant difference in MUC5AC levels between the TiO2-4D and control 2 groups. Conjunctival goblet cell area decreased after TiO2 exposure.
  
  
  
  Exposure to TiO2 nanoparticles induced ocular surface damage. Although the tear MUC5AC level increased after a single exposure, it decreased to normal levels after repeated exposures. The area of conjunctival goblet cells decreased after TiO2 exposure.
authors.affiliation: Department of Ophthalmology, Ansan Hospital, Korea University College of Medicine, Gyeonggi, South Korea.
authors.forename: Youngsub
authors.initials: Y
authors.lastname: Eom
authors.affiliation: Department of Ophthalmology, Guro Hospital, Korea University College of Medicine, Seoul, South Korea. Electronic address: crisim@korea.ac.kr.
authors.forename: Jong Suk
authors.initials: JS
authors.lastname: Song
authors.affiliation: Department of Ophthalmology, Guro Hospital, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Dong Yeol
authors.initials: DY
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Guro Hospital, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Myo-Kyoung
authors.initials: MK
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, Guro Hospital, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Bo-Ram
authors.initials: BR
authors.lastname: Kang
authors.affiliation: Department of Ophthalmology, Guro Hospital, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Jeong-Hwa
authors.initials: JH
authors.lastname: Heo
authors.affiliation: Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Hyung Keun
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Anam Hospital, Korea University College of Medicine, Seoul, South Korea. Electronic address: hyomkim@kumc.or.kr.
authors.forename: Hyo Myung
authors.initials: HM
authors.lastname: Kim
mesh_terms: D000818:Animals; D003228:Conjunctiva; D020397:Goblet Cells; D053768:Metal Nanoparticles; D055271:Mucin 5AC; D013666:Tears; D014025:Titanium
chemical_list: D055271:Mucin 5AC; C009495:titanium dioxide; D014025:Titanium
keywords: nanoparticle; ocular surface; titanium dioxide