Ernie is a pleasant 67 year-old gentleman who experienced an acute stroke a year and a half ago while driving. He was outside the window of tPA and therefore suffered right-sided hemiplegia, right facial droop, and right neglect. Due to repeated atrial fibrillation episodes, he has experienced left PCA territory infarction. Frontiers in Neurology has a nice primer on ischemic posterior circulation stroke.
Ernie’s BVA OU is reduced to a struggling 20/150 whole line, and 20/80 isolated letters. Isolating the letters on a chart helps him scan better to search for what he’s looking toward. As predicted by the slide above, Ernie has right homonymous hemianopia (RHH), visual deficits, and memory deficits. He had significant difficulty recognizing alphabet letters when we first saw him, mirroring the path a number of PCA stroke patients with RHH (Ruth always comes to mind). Here are Ernie’s visual fields:
Here’s where optics comes into play. Ernie has the following Rx in Progressive Addition Lens (PAL) form:
PALs are hard enough for any patient with acquired brain injury to function with, distorting the periphery and compromising visual-vestibular interactions. But they’re a double whammy for Ernie, because when he fixates he tends to elevate his chin and rotate his head toward the right to maximize viewing angle with his intact left field. Ernie isn’t reading yet. He’s still working in letters, so a PAL interferes with his distance vision because he elevates his chin and rotates his head to search for intact field and clarity. Also note Ernie’s myopic Rx power. When he is working on reading readiness skills, including individual letters, he can imply remove his Rx and be in focus at near. Simply to give him the convenience of one Rx, we re-wrote it as a bifocal – but it is crucial in his case to set the bifocal line considerably lower than normal due to his chin elevation and head tilt.