Patient sees reflections of light!!

[LENNY]

Ok!
We made progressive transitions for one of the patients.
the change in the Rx was very minor jus t the add by 0.50.
the frame is very simular and the fit of the new frame is the same now. The patients complains that he sees reflections of light only at night and only with his new glasses. After adjusting and readjusting, checking base curve and RX i dont know what else to do. Patient also tells me that if he raises the frame the shadows go away but the vision is blurry(more plus). So the fit is right also

Help

[chip anderson]

Over plus him to the limit that you can without making the vision intolerably blurry. If that fails try blinders and side shields.

Chip

[sticklert]

I am sure you checked but I have to ask since it was not something that was mentioned. What was the edge treatment: High luster, matte sheen, or none at all. It could be internal reflections?

[LENNY]

My edger does a regular non polished edge.
the RX is too small to cause reflections from the edges.
It is almost all covered by frame

[harry a saake]

lenny, my experince with this sort of thing, that i have seen crop up a few times over the years, is a combination of the progressive and the base curve. change it to whatever they had as far as brand, and also try and keep the base curve the same as what it was.

[Rich R]

Lenny
May also be amount of prism thinning is different, I've seen this where one pair with prism thinning and one without may create this problem.

Rich R.

[Clive Noble]

This Pt won't be happy 'till you solve the problem whether it's equithin prism differences or base curve, it could be both.

If this was my problem I'd send the lenses away for an AR coating.
It's certainly cheaper than a new pair of lenses.

I too have often been at my wits end with silly problems like this.
If I really can't see a problem with Rx, heights, PDs etc, as a last resort, I just reorder the lenses and that usually solves the problem. Sometimes the lab accepts them back and agrees there were abberations which we, as simple folk, can't always check out.

[Darryl Meister]

I would also recommend comparing the prism-thinning between the two pairs. Reflections are deviated considerably more through prisms than the actual (refractecd) images, which can sometimes make them more obvious, particularly in low powers. Although rare, progressive wearers with low Rx's may notice changes in reflections depending upon the amount of prism-thinning used. If that is the case, and the wearer cannot "adapt" to the difference within a week or two, you could look at applying an AR coating to the lenses, remaking the lenses with less prism-thinning, or playing around with the frame adjustment to see if that helps at all.

Best regards,
Darryl

[LENNY]

But why only this happens at night?

[CME4SPECS]

Lenny, it probably happens during the day as well. Due to contrast of light and darkness, it is noticed more at night. I bet on the prism also.

[chip anderson]

LENNY:

The reason it is more of a problem at night is the pupil is larger, this allows more abberations (both in the spectacle and the eye) to be allowed onto the retina. PAL's have more aberrations and a narrower field of vision than other bifocal types. The stronger the add, the more abberation. The reason I suggested crowding plus, is you reported that when the frame was pushed up the problem went away.

Now as the add increased the abberations may have become less tolerable, a PAL may not be the lens of choice for this patient any longer. Remember the statement: "PAL's are not to be used on presbyopes that are already wearing other bifocal types. PAL's are the ideal lens for the beginning presbyope." This was because the patient was used to seeing things more clearly and would not tolerate the aberrations in PAL's.

As long as we are on the subject, if you are presbyoptic you will find that for bench work and painting small details, an ST will be much better suited for your needs (I wear PAL's but I have a pair of ST's made up in intermeadiate and near for bench work and painting iris's.) Boy I expect to hear a lot of argument from PAL defenders on this one!

Chip

:cheers:

[CME4SPECS]

Chip, I believe that the reflection went away when the glasses were moved up, because of displacement, due to the prism. Terry

[David Wilson]

Hi Chip,
I think that Terry and Darryl are on the right track here. These are reflections, not aberrations. Also, I'm curious about the saying, "PAL's are not to be used on presbyopes who are already wearing other bifocal types." A collation, by Brooks, of around thirty studies (I don't have my copy in front of me so I can't give the exact details), carried out between 1985 and 1995 and published by Brooks in 1996, found that something like 83% of previous bifocal and single vision wearers prefered PALs when given the option.

Also, the percentage of PAL wearers in countries like Japan and many of the European countries are very high, much higher than the US and Australia. They can't all be young first time presbyopes; some must have been successfully changed out of bifocals.

This is not to say that everyone is a good PAL wearer. There are contraindications and there are some people who, even though there are no contraindications, just don't adapt. Many, I would think most non-adapts, though ared due to fitting rather than the lens as the shopper survey a couple of years back by 2020 magazine showed quite well.
Regards
David

[Darryl Meister]

CME4SPECS explained the most likely reason why this happens at night (or is at least more noticeable). It's just a matter of contrast. This reflection is very faint, and it will be harder to detect in a bright environment, not to mention the fact that your eyes increase in sensitivity at night. Imagine the difference between looking at a car headlight during the day, versus looking at the same headlight at night.

Best regards,
Darryl

[Optom]

Hello Lenny,

I am not very familiar with technicalities of PPL's, but I would recommend you to try out the following if it can help:

1) Fit the eyeglasses as close to the eyes as possible.
2) Ensure there is no warping of the frame. Also try altering face form to see if this helps.
3) Like prism thinning, check the base curves of each lens, it is possible for two similar powered lenses to have been made on different base curves.
4) Slightly increase pantoscopic tilt and re-adjust the frame accordingly. Also, it is not a bad idea to apply AR coating to the lenses.

And let us know how you managed to solve this problem.

Regards,
Optom

[LENNY]

Thanks a lot everybody!
I will offer a patient couple of choises.

[jon 22]

See if this rings a bell. I once had a patient that said he couldn't get used to his new lenses. I rechecked base curves, Rx, pd, and had everything lined up just proper. Still couldn't adjust. Then, I noticed that his eight year old glasses that he was used to had a terrible retroscopic tilt and almost an anti-faceform (non)wrap. You guessed it, I then intentionally screwed up the fit on his new glasses to match the old ones and now he's happy. I cringe just thinking about it.

[hcjilson]

read an article by Darryl which was the first thing I thought of. If this has been suggested please forgive my not having seen it in my cursory reading of this thread.

Darryl's article was written for Sola, describing their new Teflon AR coating. It is entitled Teflon Easy Care: A World First in Lens Coatings.Due to advancing years I am prone to forget much of what I read, but the description above of the reflections caused me to remember this quote." AR coatings eliminate the veil of refected light that masks the wearer's eyes as well as the internal reflections that causes ghost images and exacerbate the apparent thickness of the lenses.

I do not think the problem is caused by the type of lens ie. progressive vs fused. I was wondering if AR had been tried. I was also wondering what the Rx was to see if edge reflection was causing this. I had a recent case of problem reflections and solved it by putting a brown edge tint (like the kind used on rimless lenses) Just a couple of thoughts and a chance to let Darryl know his work doesn't fall on deaf ears! :D

hj

[Darryl Meister]

Just a couple of thoughts and a chance to let Darryl know his work doesn't fall on deaf ears!

I knew there was somebody out there reading that stuff! ;)

Best regards,
Darryl