Archives for: July 2012, 02

07/02/12

  04:29:00 pm, by The Dreamer   , 440 words  
Categories: Stuff, Healthcare

How to check your PD

Since I seem to have this problem recently, that seems to lead to unexplained damage to eyeglasses....I thought I should acquire some cheap spares. Like using offers that appear via deals.woot.com or such sites now and then.

But, I had a bad experience before, because my PD wasn't right.

Now, I had noticed that there was a different PD measurement listed on my prescriptions that I've been getting from Eyecare Associates....which are probably right, but I thought I should see if there was some way to check for myself.

Searching the Internet, I found these instructions.

Self measure PD in front of a mirror: you need a mirror and a MM ruler.

  • Stand with you face about 20 cm (8 inches) from the mirror.
  • Close your right eye and look only with your left eye.
  • Place a ruler flat against the mirror and align it horizontally with the millimeter scale pointing up.
  • Look over the top of the ruler and align the zero mark in the center of your left pupil.
  • Open your right eye and close the left, but do not move your face or the ruler.
  • Read the millimeter measurement corresponding to the center of your right pupil.
  • Repeat the procedure several times to make sure you have a consistent measurement.

But this is rather difficult....well, there's another procedure:

  1. Hold the mm ruler on the bridge of your nose for stability. Pretend you can look through the mirror (X-ray vision) to see the horizon far away. This keeps your eyes from rotating in toward your nose.
  2. Point your face [nose] straight into a mirror.

    --- CLOSE your left eye to avoid parallax error. ---
  3. Align the ruler's zero to the center of your right pupil. The pupil is the black spot in the middle of the eye.
  4. Without moving the ruler, close your right eye and open your left eye.
  5. Read the millimeter line under your left pupil (careful -- backwards in mirror!).

    --- Keep you face "square" to the mirror to avoid parallax error. ---
  6. Repeat two or three times to confirm accuracy.

Using this second procedure, seems to confirm the PD on record for my prescription from Eyecare Associates.

65mm.

That's kind of a big difference than the number entered at Lenscrafters (62mm). Probably explains why buying glasses from anywhere other than Lenscrafters had always been a disaster. Which they don't use in the store, rather marking PD locations on the demo lenses and making the pair from that....within an hour.

Time to see if a few $9 pairs will really work....well, they'll end up much more than that, because I'll add in things like anti-scratch, anti-glare, high-index and progressive....and maybe I'll tint one.

Now instead of subjecting some poor random forum to a long rambling thought, I will try to consolidate those things into this blog where they can be more easily ignored profess to be collected thoughts from my mind.

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