Did you cram for your eye exam? Does a cold, sweaty feeling creep over your body as you wait to go into The Room? You know, The Dark room with all the blinds drawn and the chair you plunk down into while Nurse Ratchet seems to be taking great joy in adjusting you into something that looks like old sparky, the infamous Florida electric chair. Well she looked at you like she was sizing up your left kidney for the guy out front didn’t she?
Then The Fort Collins Eye Doctor comes strolling in right on time-OK truthfully you had to wait a few minutes more alone,—in a dark room,—in a chair that somewhat resembles Old Sparky,— with plenty of time to think about what was coming next.
What’s coming next is an inadequate explanation of what we are doing as Eye Doctors or no explanation at all. Most people don’t seem to want to know, so if you are feeling two steps away from having your eyes water-boarded (which by the way we utilize eyeball water-boarding and it works exceptionally well when someone has a toxic chemical spilled in their eye), it’s time for you to start asking questions. (And for your Optometrist to take the queue and start answering them).
First and most important I personally have only given failing grades to two patients on their eye test so your chances of passing are better than 99.999%. Those two people were both receiving a failing grade in their personal relationships prior to their eye exam so if you are having a bad day and want to yell, scream and throw things it might be a good idea to reschedule you eye examination and spend the day trying out for a local hockey team.
I find a large number of patients become very concerned they will get the wrong prescription because the lens changes are so hard to discriminate. From my side of the vision exam it’s a different perspective. We start with an instrument called an auto refractor. It does exactly what it is called; automatically it focuses through the optics of your eye and using mathematics called wave front analysis it determine what prescription you need. You don’t have to do a thing except look straight ahead at the target, keep still, and have your head pressed against the top headrest. Magically things clear up after the instrument whirs and hums and prints out your prescription. We refer to this as an objective refraction or reading because it is entirely independent of your verbal responses.
Now the bad part. The assistant who wants your kidney for her brother in law escorts you back to the “room”. You know whets coming next-yes it is one or two, one or two, on or two. And you thought we had to learn math for optics? Every subsequent view looks blurry and keep getting worse. It clears up in between the two bad choices you are given but the optometrist seems intent on ignoring that and giving you even worse choices.
Actually it is a well designed testing sequence called forced choice (uh oh here comes that water board). Really, if you remember the old dial TV’s where you turned past the channel and back a few times you could bracket in to the clearest place. This part of the eye test is subjective and depends on your responses of just noticeable differences. It brackets in to the place of maximum clarity. Unfortunately, that endpoint is often where it looks equally bad with both choices. Still, we force you to make a choice. That allows your eye doctor to see how repeatable your responses are and gives a very good idea of how precise the prescription will be. Most of the time in our eye center, it will be repeatable within the accuracy level that lenses can be made in today. That means if we check you tomorrow or next week the chances are very high your eyes will read for the exact same prescription.
Next I will compare those subjective responses with what the eye computer calculated. If there are significant differences I may repeat reading with both methods after using drops to prevent focusing changes effecting the findings, especially in children. An added check may be done with a hand held instrument, the forerunner to the auto refractor we use today. While it is very low tech, it does allow me to see any variations in focusing occurring while taking an objective measurement.
Finally, a good optometrist should check your old eyeglasses prescription and how well you can see with it. That is a good indicator of how much change we expect to see in the new prescription. When you add all of these things together, it really works well and rarely is a prescription wrong per say. It is more common to misunderstand how much change a patient can tolerate (we can be right and wrong at the same time), or fail in communicating unusual visual needs that have to be addressed (like someone working on computers 70 hours per week at an unusual distance suffering from dry eyes and computer vision syndrome).
Spend a few extra minutes to communicate your visual needs and distances you work at with your optometrist. Also explain any problems you have had adjusting to new glasses in the past. Then you shouldn’t need to worry about how blurry things keep looking during your eye test-there is a 99.999% probability you will see well in the end and get to keep your kidney!