A pair of eyeballs never walks into the office. We all know that you can’t treat visual problems as if they were disembodied from the individual. A new article published in PLOS takes a look at retinal contrast transfer function in adults with and without ADHD utilizing the pattern electroretinogram, or pERG. This is in instance where although the researchers could not demonstrate any difference in adult ADHD patients on pERG, their previous work contributing to the increasing evidence pointing to visual abnormalities at the retinal level in depressive disorder should be of great interest.
What is the basis for the retina acting like brain tissue? The authors note that the pERG can serve as an objective surrogate marker of retinal information processing from the photoreceptors to the beginning of the optic nerve. In previously published studies they found that the pERG–based contrast gain discriminated patients with major depression from controls with a specificity of 92.5% and a sensitivity of 77.5%. Of particular interest is that this abnormality in contrast gain normalized when depression lifted, and remained abnormal when depression was not in remission, despite anti-depression therapy. The authors advance the theory that the key element is change in dopaminergic function. The stimulus to dopaminergic function at the retinal level may differ depending on whether high spatial frequency (small check sizes) or low spatial frequency (large check sizes) are used.
Can you think of an optometric condition in which the response to smaller size letters on a Snellen chart at distance and near are equally reduced in both eyes, with no apparent refractive error or conventional disease? Streff Syndrome. And it would be interesting to study the pERG response to varying check sizes in that condition, wouldn’t it.