Nonstandard PD. How to measure?

[Traveler]

I was born premature in 1966 and have retinal damage (retinopathy of prematurity) from prenatal oxygen. I have 20/200 in the left eye and 20/40 on a good day corrected in the right eye. However, there was some drifting of the central portion of my retina in the right eye so I do not see exactly out of the center, therefore I have had difficulty getting a correct prescription that offsets the optical centers of the glasses so that I am actually viewing through the strongest (prescribed) portion of the lens. We have tried guessing a smaller PD than the standard measurements, but it's not very exact. To make this even worse, I have a very strong prescription with high astigmatism (-8.00 125 cyl) so any error in guessing the correct PD makes the glasses quite ineffective.

They are able to make up a trial set with the correct Rx, but I'm not getting the same acuity in the prescribed glasses without physically shifting them over a few millimeters to look thru the strongest part.

Is there a procedure for measuring this discrepancy so that eyeglasses with the correct PD can be manufactured? I have been to see many OD's but no one seems to have a handle on it, and of course, opthamologists are out of the eyeglasses biz these days.

Traveler

[chip anderson]

First where do you live, if the OMD's returning to ethical practice (going out of the eyeglass business) I want to live and go into business there.

Second have you tried contact lenses, the centers should move with the eye and solve your problem, not to metion the objects on the back of the eye are larger.

Last, It would seem that monocular P.D.'s would be quite accurate, especially if double checked with the frame, dotted monocularly.

Chip

[Traveler]

Contact lenses were presented as a solution, and I am trying them, however I had some very bad luck with the first set they gave me and lost them the second day. I don't think they had the exact right rx as there was a ton more astigmatism with the contacts over the glasses. I'm going to keep trying the contacts unless I find I just can't tolerate them.

When you say "dotting the lenses" are you referring to just putting a pen mark on the lens to denote where the center should be?

Thanks for the info!
Traveler

[Shutterbug]

With high prescriptions like yours, the vertex power shift is a big issue. As lenses move toward or away from the eye, the power changes and this needs to be calculated for your exact frame. PD can also be calculated based on convergence, but this has to be measured for your exact movement.


Find a good optician and let them work with you to solve the issue. The Dr. is probably not the person you need for this particular issue :0)

shutterbug