Retinal ganglion cell dysfunction precedes death in glaucoma suspects

Abstract

Purpose: To estimate the timelag between retinal ganglion cell (RGC) dysfunction and death in patients suspected of glaucoma by comparing progressive losses of pattern electroretinogram (PERG) and retinal nerve fiber layer (RNFL) thickness over time.

Methods: Glaucoma suspects (N=107, 201 eyes) were monitored with PERG and optical coherence tomography (OCT) every six months for at least four years. Longitudinal PERG amplitudes and peripapillary retinal nerve fiber layer (RNFL) thicknesses were normalized on their respective dynamic range (difference between the values in normal subjects and advanced stages of the disease) and fitted with linear functions. Individual slopes were pooled. The time lag for PERG and OCT to lose 10% of their baseline value was calculated.

Results: In eyes with abnormal baseline PERG amplitude (50-90% loss from normal average, N=99), pooled PERG amplitude slopes took 1.9 - 2.5 years to lose 10% of their initial amplitude, whereas the RNFL thickness took 9.9 - 10.4 (P<0.05). Thus, the time lag between PERG amplitude and RNFL thickness to lose 10% of their initial values appears to be of the order of 8 years.

Conclusions: In glaucoma suspects, PERG signal anticipates an equivalent loss of OCT signal by several years.

Keywords: 507 electrophysiology: clinical • 531 ganglion cells • 496 detection