Short-Term Moderately Elevated Intraocular Pressure Is Associated With Elevated Scotopic Electroretinogram Responses

Area of Science:

• Ophthalmology
• Neuroscience
• Physiology

Background:

• Elevated intraocular pressure (IOP) is a key risk factor for open-angle glaucoma.
• Some glaucoma patients exhibit normal IOP, suggesting fluctuating IOP may play a role.
• Transient IOP elevations in rats mimic early glaucomatous optic nerve changes.

Purpose of the Study:

• To investigate early physiological retinal changes using noninvasive tests during moderately elevated IOP.
• To determine if electrophysiological and optical imaging can detect early signs of glaucoma.

Main Methods:

• Intraocular pressure was elevated to 35 mm Hg in one eye of rats.
• Noninvasive tests included scotopic threshold response (STR) and electroretinogram (ERG).
• Optical coherence tomography (OCT), Western blot, and histology were also performed.

Main Results:

• STR and ERG amplitudes were enhanced in eyes with elevated IOP compared to baseline and control eyes.
• Structural changes were observed in the optic nerve during IOP elevation.
• These findings contrast with known effects of ischemic IOP elevations.

Conclusions:

• Acute IOP elevation in rats, similar to levels in untreated glaucoma patients, increased ERG parameters.
• Further research may elucidate mechanisms of early retinal changes in fluctuating or chronic IOP.
• Noninvasive electrophysiological and imaging tests show promise for detecting early glaucomatous changes.