I am convinced we are seeing a resurgence in the use of electrophysiology in the detection and management of eye disease. This was certainly borne out by the AAO conference this year.
The Diopsys system was attracting much interest in the exhibition arena. This uses a small electrode, similar to a small plaster, secured to the face under the lower lid and produces a characteristic electroretinography (ERG) output curve when the patient views various pattern targets. A similar technique may easily generate a visually evoked pattern response (VEP).
The former curve shows changes in pattern when, for example, ganglion cell damage occurs in glaucoma, or where maculopathy changes result from use of drugs like hydroxychloroquine. The latter may detect when a visual pathway defect is reducing vision in the absence of apparent ocular disease. Having such easily and quickly performed objective testing in practice may be the biggest thing since visual fields testing.
There were plenty of research papers presented to support my view too. A presentation by Dr Kristen Bowles, AAO Ezell Fellow, showed how ERGs are refining the detection of photoreceptor dysfunction, either due to disease or drug adverse responses.
Another breakthrough in understanding of the visual pathway and its influence on vision came from ophthalmologist Dr William Sponsel and his team – members of whom had originally undertaken research at Bristol University that had led to the development of the frequency doubling technique for early glaucoma detection some years ago.
What Sponsel has shown is that, as vision is lost due to ganglion cell death in the retina of each eye, the central nervous system (at the level of the visual cortex) responds selectively in a way that maximises binocular input. This ground-breaking work implies that during diseases of the eye, the brain adapts to minimise sight loss impact on binocular vision.