Which patients benefit?
I have used visual electrophysiology testing as a diagnostic tool for many years. However, the expense and inconvenience associated with the tests necessitated a certain level of discernment on my part; deciding which of my patients would get the benefit of the additional information and who would not.
Thankfully, scientific advances now have enabled this testing modality to be incorporated into the clinic. I use an ERG and visual evoked potential (VEP) testing system (Diopsys NOVA), which employs non-invasive sensors and a straightforward operating system to make it more comfortable and less expensive for both patients and clinicians.
The test results are colour-coded based on documented reference ranges, creating an output summary that enables intuitive interpretation.
The uses of ERG tests are widespread, with applications for glaucoma; central retinal vein occlusion;3 retinal ischaemia,4 macular degeneration;5 and many other pathologies. This means that I use this testing in my clinic daily.
I perform pattern electroretinogram (PERG) on patients who have suspicious nerve shape and thickness, to determine if they have pre-perimetric glaucoma. If the tests show non-optimal cell function, I am able to start the patient on treatment that will prevent damage and preserve their vision. If the result shows good function, I can save the patient the hassle and expense of starting unnecessary treatment.
In patients with inflammatory retinal diseases, I use ffERG to understand the activity of the inflammation. This allows me to adjust the amount of steroid a patient is using, or indicates what their maintenance amount should be.