Wierd lens reflections

[BMH]

OK I am calling on the wisdom of the board.

I have a patient that has noticed a double image/reflection in his lenses when he looks at bright light sources. I put the glasses on and could see it too. I have been in this industry for 20 yrs and really can't recall seeing reflections like this.

I also wear glasses but have worn A/R coating for several years now. When standing with the patient looking at a light I don't see the reflection with my glasses or when looking through demo lenses without A/R.

I went a step further and grab several pair of completed glasses from different labs and could also see reflections in them but not as bad as the patients lens.

His lens is plano -.25 X 62 2.50add Comfort poly. The reflected image is above the light source by about 6 to 10 inches.

So here is my question. Is everone without A/R seeing reflections like this? Is this an issue with the hard coating? It is not the patients vision because I see it too.

My first instinct was just a weird coating issue so I had the lens remade but the reflection/image is still there and actually in a higher position compared to the previous lens.

To continue the weirdness his other lens is a SV plano poly balance without A/R and I don't see the reflections in that lens at all.

??????? Puzzled
BMH

[Jacqui]

Poly is probably the problem. You may need to AR the lenses.

[uncut]

Jacqui is right....the lenses, being approx 1.59 index are surface reflectant enough to warrant an AR coat, and. keep in mind the SR coat over may also contribute to the problem, but without it the surface of the lens would scratch easily. The right lens would be of a non-uniform thickness, at the distance oc due to the lens powers, and left(PL distance) would return to a more parallel surface in the distance portion of the lens.

It is common for people with minor Rx's to notice annoying surface issues, since their benefit is minimal, and removal can be percieved as "better".

These lenses wouldn't happen to be edge polished, because that would increase the phenomena?

[Ginster]

Is the Mysterious image in the form of the Virgin Mary, Or Jesus? LOL Just had to do it, could it be a steaper B.C than what the Pt. is used to wearing?

[Uilleann]

Look at A/R - don't bother wasting time trying to change the material however. At that power and in that lens design, poly is a perfectly acceptable material. It will perform more than satisfactorily.

[BMH]

Nope no virgin mary or I'd be selling them on Ebay.

@Uncut

As I looked at many completed glasses this morning I was able to recreate the same issue with several materials. The common factor on the worst ones were low powers. I guess it goes to prove you never have seen it all in this business. I am just amazed that more people don't complain of this issue.

As far as this patient, it is his first pair of Rx glasses. He has been using OTC readers but needed something to wear all the time. He is also sighted in just his right eye. I put him in a progressive which he likes just fine. From readers to progressives, it can be done. But as Uncut pointed out he has no distance Rx and of course the reflections go away when he takes the glasses off.

I am a low myope but I wear AR on all my glasses so I have not had an issue. I am going to break out a pair of my old glasses this evening and see if I notice it.

My solutions to this issue was to re-order with AR. I'll find out if that fixes it in a couple of days.

Thanks for listening

[chip anderson]

Put a baseball cap on him and see what happens.

[mike.elmes]

Many of the lens companies are using flatter base curves which compounds the reflection problems, especially on the high index. I hate poly and rarely sell it. We prefer the TL16 MR8 material. less chromatic abberation, doesnt require an edge polish, drilling is far superior...with no cracking. we only sell it with a/r, or on a sunglass with backside a/r.

[uncut]

Many of the lens companies are using flatter base curves which compounds the reflection problems, especially on the high index. I hate poly and rarely sell it. We prefer the TL16 MR8 material. less chromatic abberation, doesnt require an edge polish, drilling is far superior...with no cracking. we only sell it with a/r, or on a sunglass with backside a/r.

Great points, mike.elmes.......

@BMH;

I tend to look at abbe values of lenses as a guide to whether an AR coating is applicable. Poly- 32, 1.8 glass-34, 1.67 plastic-32, 1.74 plastic-33, 1.6 plastic-42, CR-39-58, regular glass-57. I tend to not dispense anything that has an abbe of under 50 without AR. Please note the values listed are approximate and subject to variation by brand.

[Uilleann]

Why would you ever NOT recommend and use AR lenses?? Truly?? :hammer::hammer::hammer:

[uncut]

Why would you ever NOT recommend and use AR lenses?? Truly?? :hammer::hammer::hammer:

...about times I would not use, "recommend" AR:
1) When economy is paramount to purchaser.
2) When speed(time) is of essence in production.
3) When caustic occupation is presented.
4) When light transmission decrease is a goal, whether cosmetic, or functional.
5) When chemical compostion of lens material interferes with AR stability or quality.

Don't get me wrong, I love AR.....heck I've run AR coating equipment! Done Mirror gradients, too!:bbg::bbg::bbg:
Truly!!

[Uilleann]

...about times I would not use, "recommend" AR:
1) When economy is paramount to purchaser.
2) When speed(time) is of essence in production.
3) When caustic occupation is presented.
4) When light transmission decrease is a goal, whether cosmetic, or functional.
5) When chemical compostion of lens material interferes with AR stability or quality.

Don't get me wrong, I love AR.....heck I've run AR coating equipment! Done Mirror gradients, too!:bbg::bbg::bbg:
Truly!!

Our office has a rather different outlook and approach. To each their own!

[chip anderson]

I would not recommend AR for the following:
Mechanics, woodworkers, Painters, automobile body men, oilfield workers, farmers and any number of jobs or situations where a lot of abrasive substances are involved. In fact for many of these jobs Glass is the best material. A safety lens that is so scratched that the patient can't see through it may be more of a hazard than the potential for breakage, would use proper thickness and tempering for these of course. Often wouldn't push it at least for the CL wearer that only wears glasses in bed and to find CL's.
Of course we are once again in the vision or cosmetics, or profits question
Chip

[Uilleann]

We always fit for quality of vision first - regardless. That means AR. Interestingly, we haven't had a single issue related to workplace environment incompatibility with an AR lens in years. Perhaps a different AR lens might be helpful to any practice or dispenser who is afraid of problems. This ain't your Mamma's AR lens anymore me boyos! ;)

[miwani]

The material could be a possibility. Polycarbonates are not the greatest types of lenses!!!!!!!!!

[Uilleann]

Poly is fine in that Rx. To say otherwise only perpetuates myths that have previously and quite soundly been debunked. But again...to each their own preference at the dispensing table.

[WFruit]

I tend to look at abbe values of lenses as a guide to whether an AR coating is applicable. Poly- 32, 1.8 glass-34, 1.67 plastic-32, 1.74 plastic-33, 1.6 plastic-42, CR-39-58, regular glass-57. I tend to not dispense anything that has an abbe of under 50 without AR. Please note the values listed are approximate and subject to variation by brand.

I completely agree with lower abbe value lenses needing A/R. However, abbe is not the only reason, and actually would have less to do with this issue. Generally speaking, the higher the index, the more light is reflected off the surface of the lens.

CR-39 = 7.80% reflected
Trivex = 8.70%
Poly = 10.30%
1.60 (MR-8) = 10.50%
1.67 (MR-10) = 12.35%
1.70 (Hoya) = 13.45%
1.74 = 14.40%

Thus, the higher the index, the greater need for A/R (values are again approximate and can vary slightly by vendor).

@BMH - Just curious to know if changing the pantoscopic tilt/face form of the glasses makes any difference in the reflection?

[chip anderson]

Changing the angle makes a difference in the reflection but this is dependent on where the light source is. As it is dependent with all surfaces on where the light origionates.

[DragonLensmanWV]

Just be sure to note that AR does NOTHING to correct a bad ABBE. It's plenty helpful because generally the lower ABBE lenses also have a higher reflectance.
Believe me, a -15 in AR poly is still going to be worse visually than a 1.70 without AR.
-3.00? Not a lot of difference there, AR wins.

[WFruit]

One could argue that A/R acutally makes low abbe lenses worse, since MORE light is passing though the lens and thus being scattered.

[edKENdance]

one could argue that a/r acutally makes low abbe lenses worse, since more light is passing though the lens and thus being scattered.

*head asplode*

[uncut]

You're right, guys....I shouldn't equate abbe to reflectance. The average dispenser doesn't have access to reflectance tables, from manufacturers, so I used Abbe values.

[Pete Hanlin]

Not trying to pile on regarding abbe value, but wanted to point out that- at the Rx mentioned in the example- even a material with an abbe value of 22 would likely fail to produce a noticeable chromatic effect (although it would be incredibly expensive to produce a lens out of diamond :^). You need to have prism to create chromatic aberration (specifically, prism / abbe = chromatic aberration). So, you basically can't get chromatic aberration from a plano lens (or one that is near plano). Of course, the ADD is providing some plus power, but...

I would also +1 the comments on trying a ball cap (or cup the hands around the edge of the lenses) to determine if the reflections are originating from the periphery/edge of the lens. Sometimes you can also "move" the reflection by adjusting the panto or wrap. I once had a patient who always saw a "white dot" he referred to as "blare" (which I guess is some amalgamation of "blur" and "glare") when he sat reading in his easy chair (but no where else). Turned out to be his reading light (which was positioned behind the chair), and changing the panto actually did move it to a more tolerable spot (this was back when AR was still "rented" - aka usually peeled off after a few months).

[jrumbaug]

I ran into this problem about 30 years ago, when A/R was rarley mentioned. The setup was the same.
First time multifocal wearer
lower distance power
very observant customer (that did not want to wear glasses)

With plano lens, the reflected image is equal in size to the original image. As the plus power increases, the reflected image gets larger, more spread out, and is not as noticable. With an increase in minus, the refelcted image gets smaller and also less noticeble. In my opinion, it's noticable from -1.00 to +1.00, with plano being the worst.

Hands on learning moment...If you have some sphere lens from +1.00 to -1.00 get them out and look at a light and notice the images as you tilt the lens.

[AngeHamm]

(this was back when AR was still "rented" - aka usually peeled off after a few months).

This is the best thing I've read all day.