Our robot friend Short Circuit (aka: Movie Title) said it better than all of us. For a clinician (Thats us!) to really know if the progressive lenses are fitted and positioned optimally, it is necessary for us to get some form of information, one that can be evaluated, measured, and used to base further adjustments on, etc. Refractionists have come a long way since the "Which is better, A or B" days. But, for those of us who have to fit the lenses, there isn't a whole lot out there that gives us that information, immediately and interactively. We get tons of statements from manufacturers touting their front, back, up, down and sideways designs. Personally, I don't think most of that stuff is worth a hoot unless and until the patient says: "Oh, yes . . . that's better. I don't see the _____ like I used to. Or....... "I'm seeing thus and such with these new lenses.....what can you do to get rid of that?" In fact, using a graphic feedback method, we can actually "see" what the patient sees....and can change things in whatever necessary way, to alter the response to the benefit of the wearer.
What we do know is that the patient sees "stuff" we don't see, and if that "stuff" isn't right . . . we have little language we can give them that will describe it.
In other words . . . we have a limited "language of feedback" that we can "teach" a patient that will tell us what we need to know. I was taught a method of diagnosing progressive fit that was excellent and worked well. It gave the patient an opportunity to tell me what he/she sees in such a way that not only could I correct the fit, but also get a defineable and measurable indication of what he/she is experiencing that I could use to base my decision on to make adjustments/fit, etc. We nick-named it a "TFA" or tangential field analysis. And, it actually gave both me and the patient something to look at that told us both what needed to be done. If anyone wants it, I'll do a write up or something and upload it. The technique goes back 35 years and I learned it from a Swiss optician friend. We didn't have computers and video stuff to work with in those days. But, it's your turn to teach us your techique. Maybe you can teach others things like . . . .
How does the patient describe what's happening if, while looking through the glasses, one progressive seg is higher in front of the eyes than the other?
How does the patient describe his visual experience, when the sagital distance of the respective lenses is not "right"? How does the patient tell you, while wearing the glasses, that the height of the segs is "right"?
What if the PD is not "right"? What are the indicators?
And, notice that I use the word "right." Often in terms of measurements, you can stand on your head til your ears turn red . . . . measuring and signing your life away based on the pupillometer, dots, etc. But, when it's "right" the patient knows it . . . because he knows it when they are NOT RIGHT. What's WRONG with that? But, how does he tell you in a defineable and measurable way through his feedback? And, are you "tuned in" to the nuances, grunts, ahhhs, and oooohs and other body language that makes measurements less reliable than an errent head thrust?
Those of us "old dudes" have learned that no matter what the rep tells us and the so-called lens designers lead us to believe . . . the proof of the pudding is through the patients eyes. Not ours . . .not the manufacturers.
Technique is a wonderfull thing. It is the positive proof that somebody is on the ball with his way of doing things. And, that needs to be shared. The bottom line of it all is to fit lenses and eyewear in order to provide Clear, Comfortable, Single, Simultaneous, Binocular vision. And, with respect to progressives . . . how do YOU do that?
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