patient sees better from progressives than trial frames??

**ilanh** · 06-17-2006, 11:40 PM

I recently tried to refract a patient who claimed that everything that I showed her through the phoropter was "blurry". She kept insisting that her own glasses were better than the manifest refraction that I was getting. After hearing for the 5th time how everything was "blurry" I had her put on her lenses and, sure enough, "everything looks clear". I meticulously measured her progressives (Varilux comfort) and put the Rx in a trial frame. Once again, "everything looks blurry". She very much wants a new pair of lenses but I am a bit confused as what to do. I sent the original pair of specs to the lab (with some new frames) and asked them to keep the same Rx, same base curves, same prism thinning, same lens material etc etc. Does anyone have an explanation of what's going on? Is there such a thing as base curve issues on a progressive?? This is the first time that distance trial framing yielded blurrier vision than progressives.

**chip anderson** · 06-18-2006, 07:17 AM

There are some people who can benefit by the asphericity of a progressive lens. I have had several patients who see better in aspheric bifocal lenses for distance than they did in spherical lenses at distance. They many or may not benfit by the add for near, but they claim the distance is better than they have ever seen (long time contact wearer). Have seen this in both rigid and soft contact patients. Had one yesterday with this result in my dim room office but couldn't see jack for near. Took her outside and she could see a lot better than J-1 at near and even better at distance.

Chip

**Ory** · 06-18-2006, 08:15 AM

Originally Posted by ilanh

I recently tried to refract a patient who claimed that everything that I showed her through the phoropter was "blurry". She kept insisting that her own glasses were better than the manifest refraction that I was getting. After hearing for the 5th time how everything was "blurry" I had her put on her lenses and, sure enough, "everything looks clear". I meticulously measured her progressives (Varilux comfort) and put the Rx in a trial frame. Once again, "everything looks blurry". She very much wants a new pair of lenses but I am a bit confused as what to do. I sent the original pair of specs to the lab (with some new frames) and asked them to keep the same Rx, same base curves, same prism thinning, same lens material etc etc. Does anyone have an explanation of what's going on? Is there such a thing as base curve issues on a progressive?? This is the first time that distance trial framing yielded blurrier vision than progressives.

Likely a silly suggestion, but when's the last time you had your phoropter cleaned? It's amazing to see the amount of debris that can build up. Of course that doesn't explain the trial frame.

What about lighting in the room? I've found a poorly placed light can cause major glare in both the phoropter and trial frame (I guess because of so many lens surfaces). If the patient had an AR coat that might sharpen everything up.

**HarryChiling** · 06-18-2006, 12:31 PM

Originally Posted by chip anderson

There are some people who can benefit by the asphericity of a progressive lens.

Chip has a point here in that the cornea is naturally aspheric in nature(more accurately NOT SPHERICAL) and the lens may help to compensate for some slight abberations that a spherical lens of the same power may not. Just a thought.

**rbaker** · 06-18-2006, 08:58 PM

Additionally. the lenses in the phoropter, like the lenses in your trial lens kit are flat lenses. It's amazing what "corrected curves" does for reducing spherical aberration and we all know that just a little bit of spherical aberration goes a long way. You will find a great treatise on this subject was written by Dr. Tillyer at American Optical back in the thirties. In fact, a lot of good info was published back then as AO and B&L were in heavy competition (Tillyer vs. Orthogon.)