I have 7-year old boy with an Rx of OD: -2.25 -3.50X170 OS:-3.00 -2.50 X170. He says that when he looks through his new glasses of one week that all straight lines seem curved. It's so bad that he's bumping into walls. When we put the RX into a trial frame, he says that lines are now straight. What can I do with his glasses?
Base curves? Are they on axis? Are they poly?
What do you mean by on axis? ThanksOriginally Posted by CME4SPECS
Things I would check:
pantoscopic angle
on axis....to the degree!
vertical oc height
research the lens material of previous pair, base curve
A increase in cylinder, coupled with axis change can also create this phenomena.
Eyes wide open
That's a very high power lens prescription for someone so young, meaning that he has abnormally high myopic astigmatism. Something's wrong, there. That's another issue altogether.
These are adaptation effects. The question is:
1. is this his first pair of glasses? If so, then try them full time for longer. One week is usually enough for a kid, but this is a lot of power.
2. are the frames reasonable? If they're too big or the POW stinks, that's a problem.
Also, there is no such thing as "bumping into walls". That's hyperbole. Dismiss that crap.
Also, if the kid is really trying (and that means MOM AND DAD are trying) and can't adapt (almost never happens) then cut the lens power (by, say, 1/2) and then let him adapt to it for 6 months and increase the power, later.
If this is a first pair and this rx (or anything over a 1.00 cyl) is presented I like to tell the parent to expect this and either time will fix it or the doc needs to weaken the cyl to be worn temporarily then increased to full power. The bigger the frame the more likely it will be noticed and probably why the trial frame lenses were ok.
Is the reason for the patient noticing this more on a larger frame because of Prentice's rule?
Also, if I flatten the base curve, would I be able to reduce his symptoms?
How would pantoscopic tilt contribute to the symptoms? What about face-form? Thanks
It would help greatly knowing the previous Rx. POW of previous, frame size, OC relative vertically previous vs current would also be helpful info. There is a ton of guessing without knowing these.
The amount of cyl is the same as the previous Rx. The amount of myopia increased by one diopter in each eye. If the patient is looking through the optical center, would he be experiencing any induced prism due to Prentice's rule? He's using the same frame, so the optical center is the same for him as his previous glasses. What's POW? Also, everything about the Rx was made correctly - axis, power, optical center height, PD. The BC is probably different than his previous Rx - we didn't specify it on this order. He is using polycarbonate and was also using poly in his previous glasses.
You state 7yr old. At what age was the habitual dispensed? Did you keep the PD the same as the habitual, or remeasure?
One would naturally go straight to BC difference, as that’s the easy way out. A 1D increase in myopia would naturally drop the BC processed by the lab. But, here is the catch. A 1D change in base curve generally wouldn’t create this phenomena, though a 2D change could. Was the habitual made with an aspheric lens? Was the new RX made with an aspheric lens? Perhaps the other way around?
Reason for asking. What your patient is experiencing is most likely prism related. PD, MRP, aspheric vs spherical.
And to answer your question. POW is position of wear. Panto, faceform, vertex. Generally used for freeform compensation, not for traditional grind.
I bend light. That is what I do.
Piling on to restate what others are saying: Sounds like a combination of POW and/or the new frame is larger than the old one. Also, DrK is right; "I'm bumping into walls" is almost certainly silly hyperbole.
I'm Andrew Hamm and I approve this message.
Isn't it as simple as barrel distortion caused by the extra -1.00
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