Abstract
Purpose: :
To study the effect of a short course of intermittent hyperbaric oxygen (HBO) exposure on retinal electrophysiology.
Methods: :
Six healthy eyes in six subjects who underwent HBO for branch retinal vein occlusion with foveal edema in the fellow eye were examined using multifocal electroretinography before and after HBO. Pure oxygen was administered in a pressure chamber at 2.5 atmospheres absolute pressure during one 90 min session each day for 5 consecutive days. Electroretinography was performed immediately after HBO treatment, one week after treatment and four weeks after treatment.
Results: :
Compared with the baseline examination before HBO, no significant change in mfERG responses was seen immediately following HBO, whereas shortened implicit times were found 1 and 4 weeks after HBO in the central part of retina (0o-5o) for P1 but not for N1. Specifically, the nominal change in mean P1 implicit time was -2.18 % immediately after HBO (p=0.2572), -6.35 % after 1 week (p=0.0468), and -3.69 % after 4 weeks (p=0.0252).
Conclusions: :
While the cone driven N1 component of the multifocal ERG remained unchanged, the bipolar cell-driven P1 component showed an acceleration of retinal function in the form of shortened implicit times that were detectable 1 week and 1 month after hyperbaric oxygen exposure but not by the end of the week when hyperbaric oxygen was administered. Reduction of implicit times has previously been demonstrated to follow immediately after an increase in glycemia. This suggests that common mechanisms may be involved in retinal adaptation to supply variations in its principal energy substrates.
Keywords: electroretinography: clinical • retina: distal (photoreceptors, horizontal cells, bipolar cells) • oxygen