By: Brian Oulman, OD
I want to walk you through a process and let you in on a little secret. A secret that 90% of opticals don’t do or just don’t know about: Proper Personal Eyewear Measurements known as Position of Wear measurements (POW). If you have ever purchased eyeglasses to see better, I hope you had more than 2 forms of personal or POW measurements taken. You are probably thinking, what is the position of wear measurements? Great question and let me answer that.
The POW measurements include the Pupillary Distance, the Optical Center or Segment Height Distance, the Vertex Distance, the Pantoscopic Tilt and finally the Wrap Measurement. Yes, there are a total of 5 measurements that are needed to ensure your new prescription lenses inserted into your frame are as precise as possible. These are medical devices and Central Oregon Eyecare opticians know this and take pride in their knowledge to help you see better. Now, I would like to further explain each POW in greater detail and why they are so crucial.
The pupillary distance is simply the distance between your eyes, to center the lens horizontally. The optical center is measured from the bottom inside part of the frame to the center of your pupil, whereas the segment height determines where a progressive, bifocal or trifocal segment begins. The optical center and segment height are taken to ensure the exact vertical height. The segment height is measured from the bottom inside part of the frame to either; the center of your pupil for progressives, the lower lid margin for bifocals or the lower pupil margin (the location on the bottom where the black circle of your eye meets the colored part or Iris) for trifocals. The vertex distance determines how far your frames will be from your eyeball and extremely important for high prescriptions. For many prescriptions as the distance increases or decreases the prescription actually is different and needs to be adjusted for the surfacing of your new lenses. The pantoscopic tilt determines the angle of your frame and lastly, the wrap angle measurement determines the curvature of your new frame.
With your input and cooperation, our doctors obtain a new prescription to help improve your eyesight. Our opticians are some of the finest in the industry and have been trained to take all 5 of these measurements. The importance of these is to make sure you are actually using the exact prescription the doctor gave you. If these measurements are not properly taken, it is a coin toss if you are using the prescription obtained in the exam room with the doctor. Most opticals will take 2 measurements, the pupillary distance and the optical center or segment height distance, but is that enough, as you can now see the answer is NO! If these personal measurements are not taken, patients may have induced prism in their lenses causing eye strain, a pulling sensation, and overall uncomfortable blurred vision. Most patients will be frustrated and think the prescription is way off when in reality it was the measurements that were wrong or not taken. Patients have the ability to purchase their eyeglasses in all sorts of settings, even online in today’s world. Eyeglasses are medical devices and should be considered as such, that is why Central Oregon Eyecare goes above and beyond to ensure your medical device is as precise as possible while looking good in your new frame style. Please make sure you and your loved ones have their yearly eye health examination to SEE the difference!