I need lens advice

[hip chic]

Hi Fellow Optiboarders,

I am wondering if I could get some opinions. I have a customer with the following RX:

OD) -1.25
OS) +2.00

She is a young girl and obviously concerned with the cosmetic appearance of her specs. I want to do whatever I can to minimize the difference in the appearance of her eye size when she's wearing her new specs.

I am thinking that it may be best to use two different plastic lenses...different indexes? Obviously the left lens would be aspheric...is it crazy to only have the left asheric? But, I'm getting ahead of myself...I really wanted to hear from some of you optical gurus....

Thanks, in advance, for your help.

hip chic

[jherman]

Just my oppion, little kid(impact resistance), small frame. Should work ok.

[For-Life]

Hi Fellow Optiboarders,

I am wondering if I could get some opinions. I have a customer with the following RX:

OD) -1.25
OS) +2.00

She is a young girl and obviously concerned with the cosmetic appearance of her specs. I want to do whatever I can to minimize the difference in the appearance of her eye size when she's wearing her new specs.

I am thinking that it may be best to use two different plastic lenses...different indexes? Obviously the left lens would be asheric...is it crazy to only have the left asheric? But, I'm getting ahead of myself...I really wanted to hear from some of you optical gurus....

Thanks, in advance, for your help.

hip chic

Use an aspheric poly on both lenses. What it will do it flatten the curves and reduce the minification on the mnus lens, and reduce the magnification on the plus lens.

[hip chic]

Ugh-Ohhhh...

I'm showing my age (43) by saying that my patient is a young girl (she's about 23).

hip chic (...old...but, still really, really hip)

[mullo]

Use an aspheric poly on both lenses. What it will do it flatten the curves and reduce the minification on the mnus lens, and reduce the magnification on the plus lens.

This would be my exact choice also.

[misunderstood]

Use poly aspheric (surfaced, not stock), specify knife edge for the plus lens, and suggest AR......should come out nicely.

[spazz]

Use an aspheric poly on both lenses. What it will do it flatten the curves and reduce the minification on the mnus lens, and reduce the magnification on the plus lens.

Ditto.:)

[ikon44]

how about contact lenses, they will make the anisometropia much easier to deal with. with this rx no matter what lenses you use there will be problems,as mr scott of star trek used to say "ye cannot change the laws of physics"

[chip anderson]

I'm with IKon but I have seen a lot of SV with greater difference In Rx do just fine in SV anything. (This one scares you just because one is + and the other - although the effect is the same if each were + or minus)Such patients move their head to minimise the distortions and displacement from center. Now with a bifocal and same distance Rx you might or might not have a problem.

Chip

[Spexvet]

Make the base on the minus lens a little steeper than usual, and the base on the plus lens a little flatter than usual to minimize the difference.

[Stopper]

What is the acuity in the +2.00D eye?

Cheers

[hip chic]

Spexvet,

I was wondering if this might help...along with using high index plastic or polycarbonate lenses. Does anyone else have an opinion on this...i.e. steeper base curve on minus lens and less base curve than usual on plus lens?

Stopper,

I am an independent optician filling her own Dr's Rx. I'm afraid I don't know the visual acuity.

By the way...this patient DOES usually wear CL's but, wants to be able to give her eyes a rest once in a while...and wants to feel comfortable wearing her specs out in public.

Again, thanks for all the great feedback and opinions.

hip chic

[Jason Carruthers]

No one said anything about frame style, which will affect appearance as much as, or more than lens choice.Ideal frame would be thick, dark, plastic to hide lenses.

[drk]

You know, all these cosmetic changes in base curve and material actually work against her visual comfort, not that a 23 y.o. female would care about visual comfort over cosmetics...

Per anisekonia training: the correct answer is to order the job with equal base curves (whatever you'd do for the +2.00) and equal center thicknesses to minimize the disparity of retinal image sizes due to the "shape factor". There will still be some retinal image size disparity due to the "power factor". Relatedly, it minimizes the difference in eye appearance, as well.

Of course you would specify splits and levels.

As to material, spherical CR-39 should work just fine, if there are no contraindications. Since steepening the base curve OD will theoretically reduce the acuity, it's nicer to use a clear polymer.

AR is, as always, recommended.

Probably a more modern approach would be to utilize an aspheric OS to reduce image size magnification, but it would be very difficult to quantify, since various aspherics have various eccentricities. Someone, somewhere would be able to quantify this, but I've never heard of any clinically useful protocols for aspheric lens design in anisometropes.

[ikon44]

frame choice is important, i would suggest if possible oval eye small as possible,you have to bear in mind that if she looks 10mm down from the oc you are looking at 3 dioptres of vertical prism, so a shallow oval will help.

[chip anderson]

No prism imbalace if she moves her head as she will. Image imballance probable negligable. Any fancy lenses used will probably only help her cosmetics and your pocket.


Chip