Steroid-Induced Ocular Hypertension Model in the Mice

ABSTRACT

PURPOSE: To determine whether rat eyes develop increases in intraocular pressure (IOP) in response to a topically applied corticosteroid and to investigate the relationship between ocular hypertension and apoptosis of retinal ganglion cells. METHODS: IOP was monitored by rebound tonometry in a group of 10 rats that received topically administered dexamethasone in both eyes (experimental) and in another group of 5 rats that received artificial tears (control) three times daily for 4 weeks after the establishment of baseline IOP values. Only eyes that increased by more than 50% compared with the basal IOP were administered once per day for 5 weeks. After 8 weeks, selective immunofluorescence stain for retinal ganglion cells and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) stain were conducted. RESULTS: Among 20 experimental eyes, 11 eyes (55%) showed a greater than 50% increase in IOP compared with basal IOP. After 8 weeks, the mean IOPs for the experimental and control groups were 11.8 +/- 1.4 mm Hg and 18.5 +/- 1.0 mm Hg, respectively (p < 0.01). The counts of central retinal ganglion cells (RGCs) were 2718 +/- 240 and 2612 +/- 443, respectively (p = 0.294). The results of the TUNEL stain also showed no differences. CONCLUSIONS: Rat eyes exhibit a steroid-induced ocular hypertensive response with no local complications. However, maintaining ocular hypertension increased by 50% for two months was not enough to detect changes in RGCs.