Acuity is Hard
It's back to school! The busiest time of the year for optometrists. Everyone needs new glasses and contacts, preferably before school starts! It's also the time of year most kids are getting their sports physicals to participate in football, volleyball, tennis, track, etc etc etc. That brings us to today's topic: acuity. It's simple, right? Cover one eye, read letters, write down the numbers. Easy! SO EASY, in fact, that almost anyone can do it! School, DMV, pediatrician's office... so why am I even bringing this up? Well obviously because too often those people are coming up with crazy/wrong vision measurements. We get them all the time. The pediatrician's office told the mother of a recent patient of mine that her daughter had "terrible" 20/50 acuity in both eyes with her NEW contacts on...the ones I prescribed two months ago. This mother was naturally distraught! I mean they JUST PURCHASED A WHOLE BUNCH OF BOXES OF CONTACTS! Are all of those contacts now RUINED!? Naturally when we retested her vision she was 20/20 with those same contacts on. Actually she was 20/15! I had another patient just this morning who was tested at their sports physical and was told his left eye was "20/100". When we re-tested he was 20/20. Almost every day I get someone who "fails" the DMV acuity test who is easily 20/20. And of course we get the opposite as well: the school nurse "passes" a child on their vision screening...we test them and they're 20/200 and moderately nearsighted. So how does this happen? Here are some the factors in play for incorrectly measuring subjective visual acuity: wrong test distance/calibration, allowing the patient to press their hand/occluder into one eye VERY HARD while testing the other eye, not pushing the patient to guess at all, allowing the patient to look around the occulder, allowing the patient to squint, and falling for an obvious faker. In the case of the DMV the culprit is often the device they use which often has opposing polarized lenses. Basically nobody but the eye doctor's office really knows what they're doing. It's bad. When someone tells me they've been told they're 20/xx it literally means nothing to me. Could be bad acuity, could be fine...not enough information. So if the sports physicals people "fail" your son or daughter for vision and you have to come to the optometrist...don't fret! Often they're fine.