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BLOG: Glasses can change how patients see, feel
by Deborah Zelinsky, OD, FNORA, FCOVD
The eyes provide a direct connection to the brain — because the retina is made from brain tissue. When light strikes the neural portion of the retina, it activates brain function in a point-to-point representational map.
This connection between a visual stimulus (light) and the neural tissue is integral not only to eyesight, but also to the regulation of many other physical functions, including posture, sleep and blood pressure.
Anyone who has ever tried on someone else’s glasses understands intuitively that the wrong prescription can make you feel bad internally (ie, dizzy or nauseous). But it is much less well understood that the right prescription can make you feel better internally. This type of prescription relies on the activation of the hypothalamus via the retino-hypothalamic tract and the brainstem via the retino-collicular pathway
For example, I saw a patient with a functional midline shift who was continually straining his neck muscles. Weekly chiropractor visits provided relief, but within a few days his neck and shoulders hurt again. By prescribing glasses with a little blur in the nondominant eye, the patient reflexively shifted his head position and relaxed his neck muscles, while fixating his dominant eye more accurately because the peripheral signals of the two eyes helped him efficiently localize the target.
I have also seen patients with imbalanced cylinder axes. When each eye is refracted separately behind a phoropter, the measured axis might be 20° in one eye and 180° in the other, but this leads to a shift in the lower back that can be quite uncomfortable. Patients with imbalanced axes sometimes find that crossing their legs improves comfort, but in some situations — sitting at a desk in school, for example — the legs can’t easily be crossed. Children end up using cognitive reserves just to compensate for the discomfort, leading to attention and short-term memory problems. We can address that by balancing out the cylinder axes so that they add to 180° (or are each 180°).
There is much more to correcting visual processing than just sharpening central eyesight. Consider that according to Patrick Quaid, MCOptom, FCOVD, PhD, approximately 6% of the visual field is dedicated to central targets, while the remaining 94% is for peripheral retinal processing. We use our central eyesight for stationary targets (like an eye chart or a book), but seeing moving targets is highly dependent on peripheral eyesight. Moving targets are found all around our environment, including on screens used in GPS navigation systems or website scrolling. We use peripheral and central eyesight as a team to scan and shift gaze from place to place, such as from a dashboard to the road when driving, or from a desk to a teacher or from a tennis ball to a player.
Optometrists have many tools available to address deficits or imbalances in both central and peripheral eyesight, including standard lenses, yoked and nonyoked prisms, tints and occlusion filters. With knowledge about how each of these tools works, optometrists are in a prime position to affect both their patients’ external eyesight and their internal physical health.
Have you seen patients whose posture or level of comfort changed after being prescribed specialized lenses? Comment here on your experiences.
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Deborah Zelinsky, OD, FNORA, FCOVD, is director of research at the Mind-Eye Institute in Northbrook, Ill. She is an active member of the World Brain Mapping Foundation and a community leader for the Society for Neuroscience. The past 30 years of her optometric career have been spent developing methods for assessing brain function with emphasis on the often-untested link between eyes and ears. Zelinsky is also spearheading a campaign to “Leave 20/20 in the 20th Century,” because it is no longer sufficient in lens prescribing.
Zelinsky will be speaking on, “The importance of a mind-eye connection” on Sept. 20 at the NORA annual conference, Sept. 19-22, 2019, in Scottsdale, Ariz. Her 7-hour talk will review the tools available to optometrists to help patients feel more comfortable, with a particular emphasis on how to look at a prescription, convert it into spatial changes and understand how it might affect posture. For schedule and registration, visit: https://noravisionrehab.org/about-nora/annual-conference.
Disclosure: Zelinsky reports no relevant financial disclosures.
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