Intraocular pressure lowering is associated with an increase in the photopic negative response (PhNR) amplitude in glaucoma and ocular hypertensive eyes.
PURPOSE The aim of our study was to determine whether IOP lowering in glaucomatous and ocular hypertensive (OHT) eyes leads to an improvement in the full field photopic negative response (PhNR) of the electroretinogram. METHODS A prospective nonrandomized interventional cohort study was conducted. Patients with OHT or glaucomatous optic neuropathy were recruited, and photopic full field electroretinograms (ERG) were performed at baseline and then repeated 1 to 2 months later. The change in PhNR amplitude was compared between those eyes that had a significant lowering in IOP (defined as >25% decrease from baseline or to a predetermined target IOP) during follow up and those that did not. RESULTS From a cohort of 30 eyes, 18 eyes had a significant reduction in IOP during follow up (n 18) and 12 eyes had no significant change in IOP <25% reduction in IOP, n 12) A significant increase in PhNR amplitude and the PhNR/b wave amplitude ratios was observed in the reduced IOP group, but not in the IOP stable group for the two flash intensities used (2.25 and 3.00 cd.s/m(2) CONCLUSIONS The full field PhNR amplitude provides a potentially reversible measure of inner retinal function that improves after IOP lowering. Further study now is required to assess its use as a measure of optic nerve health in glaucoma patients.
Investigative ophthalmology visual science