Vision is Subjective

A few things that I frequently talk to my own patients about that might be of some use to you out there is internetland:

1) Vision is subjective. What do I mean by that? Mostly what I am referring to is that the perception & description of "blur" varies greatly between patients. It is anything but standard. We're talking about "how blue is the sky" and "on a scale of 1-10 how much does it hurt to have your foot smashed when someone steps on it" kind of thing. What is & is not "blurry" and how to describe to another person exactly what you see is virtually impossible to ACCURATELY PINPOINT. And even if we could exactly pinpoint to the Nth degree how blurry your vision is...as eye doctors we really can only do TWO things: a) eliminate refractive error and b) treat existing eye disease. If you have no eye disease and you're wearing the correct Rx...that's all we can do. Most people are happy with that, but some 20/20 patients will still tell us "it's so blurry". Ok, we believe you! But...we're limited by what we can do about it. There are other things besides disease & refractive error that cause blur, mostly optical aberrations: spherical aberration, coma, pincushion/barrel distortion, chromatic aberration, field curvature, etc, also macular cone spacing...but we can't really DO anything about any of those here in the real world. Just measuring them in a human eye takes special expensive lab equipment, and we cannot (yet) make a pair of glasses that would eliminate any of those other optical aberrations. Sometimes we have to tell healthy patients with good Rx's that we're at the limit of how "clear" we can make their vision.

2) Subjective testing is what it is: subjective. Ok so we just got finished reading a diatribe on how vision is subjective...but don't we optometrists base our glasses Rx's off of "subjective refraction"? Well yes & no. By the time we have you in the chair & behind the phoropter we've already taken multiple OBJECTIVE measurements on your eyes & refractive status. So we know basically what we're going to Rx you...possibly exactly what it's going to be. So we let you "fine tune" your Rx by offering you a little more or a little less, a little to the left & a little to the right, etc. But there are no "wrong" answers here. If you "choose" something way off, we're not giving it to you. Plus a lot of the time we're "bracketing" anyway...showing you just to the left & just to the right of your Rx but NOT RIGHT ON. So there REALLY isn't a wrong answer there...they're BOTH BLURRY choices. This is one reason why so many people get frustrated by the process of subjective refraction: they assume (incorrectly) that the lenses are "supposed" to be getting subjectively clearer with each successive choice. But they're not. That's not how it works. You're really relying a lot more on the skill & experience of the doctor than you are on your own choices behind the phoropter. That's why it's important to find an optometrist that you connect well & communicate well with.

3) If you hear hoofbeats, think "horses", not "zebras". This is a derivation of Occam's Razor: the simplest solution is probably the correct one. If you're a contact lens wearer & your eye is red, it's probably from contact lens wear. It is probably not "pink eye", etc. It *could be* contagious viral or bacterial conjuntivitis, but that's not the MOST LIKELY cause. If your head hurts it's probably a tension headache, not a tumor. Ok it *could* be a tumor...but statistically it's probably not. Especially in the age of the internet, often patients Google their own eye symptoms/conditions & come up with some very IMPROBABLE scenarios ("zebras"). Even some docs do this. I had a patient with known, longstanding neurological deficits and known, longstanding ataxia (can't walk w/o falling down), and his neurologist referred him for another eye exam saying it "could be" his glasses. Well ok yes it "could be"...but the patient had been here annually for eye exams and his refractive status was virtually unchanged in 20 years. His ataxia is PROBABLY NOT the result of an incorrect glasses Rx. That's a "zebra" for sure.

4) A lot of eye conditions have the same symptoms: The human eye can only respond in a limited number of ways - pain, redness, foreign-body sensation, vision loss, light sensitivity. That's pretty much it. Consequently many patients will call me asking me to please refill their eye drop Rx from 2.5 years ago b/c "it's the same thing again." Well, how do you know it's the same thing? You don't. There's no way for you to know it's the same, or even for ME to know it's the same unless I *LOOK* at your eye. Listing the symptoms again (foreign body sensation, redness, blur, etc) over the phone does not help much, b/c most symptoms are the SAME for most eye conditions. Someone has to LOOK at your eye anyway.