Does an IOP spike affect retinal function?
Despite the well-known association between IOP and glaucoma little is known about how short duration changes in IOP (“spikes”) affect retinal integrity. Recent research from our laboratory (1) has considered this problem in rats (n=6-7 per group) by cannulating the anterior chamber and elevating IOP to 50 or 70 mmHg for periods of 15-60 minutes. Retinal integrity was quantified by measuring the retinal response to full-field flashes of light (i.e. the electroretinogram, ERG) and quantified in terms of specific ERG components known to reflect function of outer retinal (photoreceptor, P3), middle retinal (ON-bipolar cell, P2) and ganglion cell (scotopic threshold response, STR) layers. We assessed both the loss of function and how quickly function recovered from a given IOP challenge. We found that 50 mmHg spikes (35 mmHg above baseline for 42 minutes) particularly compromised ganglion cell responses (STR 80 +/- 7% reduction), leaving outer retinal responses largely unaffected (P2, 33 +/
