Effect of single IOP elevation on visual pathway

Abstract

Purpose : To investigate short- and long-term effects of a single acute intraocular pressure (IOP) increase on the survival of retinal ganglion cells (RGCs) and on mouse vision as measured by visual evoked potential (VEP). Understanding these effects will potentially aid in tracking progression of glaucoma, in particular the influence of circadian IOP fluctuations on disease outcomes.

Methods : Unilateral intraocular hypertension was induced for 1 h to 30, 50 and 90 mmHg in wild-type mice, and their ocular health was analyzed after 7 and 21 days. RGC survival was assessed by fluorescent microscopy of Brn3a stained whole retina flat-mounts. Visual function loss was studied using VEP measurements.

Results : Acute intraocular pressure elevation resulted in RGC death correlative to IOP in all experimental groups at 7 days post-IOP. VEP showed functional losses following the same trend as RGC loss. Eyes showed minimal recovery in both health measures in the long-term cohort at day 21. Importantly, even a low IOP of 30 mmHg resulted in a significant, non-transient reduction in RGC count and the peak-to-peak amplitude of the N1 component of VEP.

Conclusions : These experiments demonstrated that the moderate IOP elevation recapitulated RGC loss and visual impairment observed in glaucoma patients and thus could be exploited as a tool to study glaucoma biology and to develop novel therapies.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.