Abstract
Purpose: :
Laser-induced primate glaucoma is a standard model used in glaucoma research and pharmacologic testing. We sought to characterize the baseline corneal health and anterior segment inflammation in cynomolgus monkeys with established laser-induced glaucoma.
Methods: :
Cynomolgus monkeys had standard argon laser-induced ocular hypertension (Power 1.0-1.2 w, time 0.5 sec, Spot size 50um) in 1 eye 2 years prior to study entry. Cohort 1 had an IOP measurement, flare readings (photon count/ms) from a KOWA FM-600, and corneal health was assessed by specular microscopy (cells/mm2) and pachymetry (mm). Cohort 2 had biomicroscopy performed to quantify AC cells using the SUN criteria.
Results: :
Cohort 1: 12 monkeys were examined and IOPs in the OHT eye 38.4 ± 3.6 mmHg and 21.0 ± 0.5 mmHg in the fellow eye (p = 0.0005) (mean ± SEM). Flare grades were not elevated in the OHT eyes compared with the fellow eye (9.5 ± 2.6 and 9.7 ± 2.6, p = 1.0, respectively) Corneal endothelial cell density was decreased in the OHT eye vs. the fellow eye, 2472.2 ± 249.9 and 2959.8 ± 196.4, respectively (p = 0.2). Corneal thickness was 0.48 ± 0.01 in the OHT eye vs. 0.44 ± 0.01 in the fellow eye (p = 0.1). Cohort 2: 7 monkeys were examined and 5 had AC cells, mean 0.8 ± 0.4, range 0 to +3. The fellow eyes all had AC scores of 0.
Conclusions: :
A chronic anterior uveitis can be present in a laser-induced primate model with trends demonstrating reduced corneal endothelial cell density. The mechanism in not known but may relate to ocular damage that occurs with sustained intraocular pressures > 35 mmHg over an extended period of time. The presence of low grade inflammation and reduced corneal endothelial cell density can be a significant sign of toxicity with local ocular drug therapy and this underscores the importance of a detailed baseline ophthalmic examination prior to initiating pharmacologic testing. The extent to which a chronic anterior uveitis confounds IOP measurement in this OHT model is currently under investigation.
Keywords: uveitis-clinical/animal model • cornea: endothelium • imaging/image analysis: non-clinical