title: Intraocular pressure with rebound tonometry and effects of topical intraocular pressure reducing medications in guinea pigs.
abstract: OBJECTIVE
  To investigate the intraocular pressure (IOP) of adult guinea pig eyes with rebound tonometry (RBT), and assess the effects of four distinctive topical IOP reducing medications including Carteolol, Brimonidine, Brinzolamide and Latanoprost.
  
  
  METHODS
  The IOPs of twenty-four 12-week-old guinea pigs (48 eyes) were measured every two hours in one day with RBT as baselines. All the animals were then divided into four groups (Carteolol, Brimonidine, Brinzolamide and Latanaprost groups,n=6). The IOPs were measured and compared to the baseline 1, 2, 3, 5, 7, 9, 15 and 24h after treatment.
  
  
  RESULTS
  The mean baseline IOP of 24 guinea pigs (48 eyes) was 10.3±0.36 mm Hg (6-13 mm Hg) and no binocular significant differences of IOPs were observed (t=1.76,P>0.05). No significant difference of IOP in Carteolol group at each time point was observed before and after treatment (t=1.48,P>0.05). In Brimonidine group, IOP was 2.2±1.9 mm Hg lower than the baseline after one hour (t=3.856,P=0.003) and lasted for one hour. In Brinzolamide group, IOP was 1.4±1.1 mm Hg lower than the baseline after one hour (t=4.53,P=0.001) and lasted for 7h and the IOP declined most at 3h. In Latanaprost group, IOP was 2.1±1.3 mm Hg lower than the baseline after one hour (t=6.11,P=0.001) and lasted for one hour.
  
  
  CONCLUSIONS
  The IOP of guinea pig eyes is relatively stable compared to human eyes. In four reducing IOP medications, no significant effect of Carteolol is observed. Brinzolamide has the longest duration, while the Brimonidine has the shortest duration and the maximum level of treatment.
authors.affiliation: Department of Ophthalmology, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200062, China; Department of Ophthalmology, Jinshan Hospital, Fudan University, Shanghai 201508, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Di
authors.affiliation: Department of Ophthalmology, Jinshan Hospital, Fudan University, Shanghai 201508, China.
authors.forename: Xiu-Mei
authors.initials: XM
authors.lastname: Luo
authors.affiliation: Department of Ophthalmology, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200062, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Qiao
authors.affiliation: Department of Radiology, Huashan Hospital North, Fudan University, Shanghai 201907, China.
authors.forename: Na
authors.initials: N
authors.lastname: Lu
keywords: Brimonidine; Brinzolamide; Carteolol; Latanoprost; guinea pig; intraocular pressure