Polycarb lenses

[learnaboutit]

I may not be supremely vain, but I would like a somewhat thinner lens. In a few years when I'm less myopic, I'll go for regular crown glass.
I read somewhere that the human eye cannot tell when the Abbe value is higher than 40. Is this true?

If abbe value is your main concern then why pick a lens with only a value of 10 better than poly. Really you should pick regular plastic with a 58 abbe value or regular glass with a 60 abbe value. That would give you a value of 26 to 28 better than the best poly. Make sure you do it with AR.

[ikon44]

Of course wearing contact lenses gives me great vision, but I've basically stopped wearing them because of dry eyes and lifestyle change.

you dont say what type of contact lenses you have been using, but if dry eyes
are your main problem, then a silicon hydrogel lens like night&day should sort it out . Also johnson & Johnson have a lens called acuvue advance which I have found works well , with dry eye situations.

[learnaboutit]

I was put into Freq 55 Aspheric lenses, but I'm really not interested in wearing contacts anymore. Thanks, though.

[For-Life]

I may not be supremely vain, but I would like a somewhat thinner lens. In a few years when I'm less myopic, I'll go for regular crown glass.
I read somewhere that the human eye cannot tell when the Abbe value is higher than 40. Is this true?

I have an rx similiar to yours and I cannot tell the difference between poly and regular plastic. Saying that I wear aspheric poly. In theory an abbe value over 40 can be detectable, so that is not true.

[chip anderson]

If you are seeing things "outside the lenses" something is wrong with your contact lens fit. The main advantage of a good contact lens fit is the center of the lens moves with the center of the eye thereby creating the best possible vision. If you eye moves faster than the lens or the lens doesn't center something is wrong there.


Chip:cheers:

[Robert Martellaro]

If you have any opinions about the sola 1.6 finalite, I'm all ears.

Excellent material. Relatively high abbe of 42, and for 1.6 index, an unusually low specific gravity of 1.22g.cm3. That means it will be much lighter in weight than the Zeiss or Essilor 1.6. Last I heard it had to be surfaced which requires a slightly thicker center thickness of 1.5mm. Until Sola introduces this in finished form I prefer the Seiko 1.6. It also has a low density and is available in finished form with a 1mm CT. I-coat has this in stock with the Vivix anti reflection coating.

[Robert Martellaro]

I read somewhere that the human eye cannot tell when the Abbe value is higher than 40. Is this true?

My understanding is that our eyes have a couple diopters of longitudinal chromatic aberration (or axial chromatic aberration) which is more than what is found in ophthalmic lenses.Transverse chromatic aberration can be greater with ophthalmic lenses and will cause loss of acuity when .16 prism diopter is induced. The formula for TCA is cF/V. C is the distance of the eyes gaze from the OC in centimeters, F is lens power and V is the Abbe number.

Robert

[David Wilson]

Following up from Robert's comments. Dan Torgerson wrote a very good paper a few years back in which he says that when TCA reachers 0.16 the acuity drops one line. From memory, he also calculated TCA at a 15 degree viewing angle and a 30 degree assuming that 80% of your vision falls within a viewing angle of 15 degress. Furthermore, Prof Mo Jalie of the UK argues that TCA is not noticeanle below 0.1. I think that it may have been Torgerson who also pointed out that axial chromatic aberration is masked by the eye's own significant ACA.
Regards
David

[learnaboutit]

WOW! Thank you both for the TCA formula and all this invaluable information. I am completely fascinated :) and I'll be looking into the Seiko 1.6, which I wasn't aware existed with the abbe 42.