Relationship between Elevated Intraocular Pressure and Divided Peripapillary Sector Retinal Nerve Fiber Layer Thickness in a Cynomolgus Monkey Laser-Induced Ocular Hypertension Model

Aims: We investigated the relationship between elevated intraocular pressure (IOP) and changes in global and peripapillary sector retinal nerve fiber layer (RNFL) thickness around the optic nerve head (ONH) in the laser-induced ocular hypertension monkey model. Methods: To induce high IOP, green laser photocoagulation burns were applied around the trabecular meshwork of 1 eye from each of 12 cynomolgus monkeys. The animals had been acclimated to IOP measurement under conscious conditions for more than 2 months, and IOP was chronologically measured. RNFL thickness was measured for 6 peripapillary sectors and global area using spectral-domain optical coherence tomography. Results: After model induction, marked IOP elevation and enlarged optic disk cupping were observed. Thinning of the RNFL associated with elevated IOP was observed around the ONH from 6 until 9 weeks after laser treatment, and the degree of reduction in RNFL thickness varied between the peripapillary sectors. Correlations between cumulative IOP elevation and RNFL thickness reduction were statistically significant for the temporal-superior (p = 0.024), nasal-inferior (p = 0.044), and temporal (p = 0.049) sectors, and global RNFL (p = 0.018). Conclusions: These results suggest that this model reflected the pathology of clinical glaucoma in terms of the specific pattern of RNFL thinning around the ONH.