degrees of eye swivel built into corrective eyewear?

[msc]

On avg., when fitting someone for infinity correction eye wear, how many degrees can the eye swivel before the correction is compromised due to the change in eye-to-glass distance? (or any other reason)

+/- 20 degrees? less?

[chip anderson]

Be done ta depending on the strength of the lenses. Mo's swivel fo lo powa, less swivel for hi powa.

Curvatures of lenses can also be manipulated to increase or decrease the effect.

Contacts and eliminate the need for even concidering the effect.

Chip

[HarryChiling]

Usually 30 to 35 degrees.

[msc]

Harry, is that a total of 30 deg. swivel? i.e. +/- 15 deg.

or did you mean +/- 30 degrees?

Thanks

[HarryChiling]

harry, is that a total of 30 deg. Swivel? I.e. +/- 15 deg.

Or did you mean +/- 30 degrees?

Thanks

+/- 30

[chip anderson]

Don't really want to dispute Harry but steeper posterior curves, mounting closer to eye, and other factors (aspherisity for one) can effect this.
Also the power has a lot to do with it. Low powered lenses can allow much more eye rotation.
Very high powers such as aphakic lenses a whole lot less with scotomas in what field is available.
Harry and Daryll can give you the math but one will find that in strong to medium powers the acuity drops off in a hurry as one moves from optical center.
Now when one introduces things like progressives the deviation allowed for clear vision is greatly reduced.

Chip

[Darryl Meister]

With a well designed spectacle lens, vision is seldom compromised within the range of normal eye rotations. Extended eye rotations are typically accompanied by a compensatory head rotation that minimizes the total angle of eye rotation.

Historically, however, lens designers have traditionally ensured "good" optical performance out to at least 30 degrees, as Harry indicated. And, to Chip's point, optical errors are typically proportional to the power of the lens.

[chip anderson]

Dr. Louis Girard, M.D. who was the chief of ophthalmology at Baylor for many years and also unilateraly aphakic and amoung other things quite interested in photography, used to have a lot of excelent slides.
The slides illustrated what he saw with his phakic vs. aphakic eye.
I suspect he and Baylor still have copies.
These were quite revealing about how power could affect peripheral vision both in spectacles and contact lenses.

Chip

[msc]

Thanks for the responses....

I assume these answers are all applicable when the eyewear contains astigmatism correction as well?

[HarryChiling]

Thanks for the responses....

I assume these answers are all applicable when the eyewear contains astigmatism correction as well?

Yes, however unless you're using atoric lenses an astigmatic lens is going to have a comprimise on either primary meridian, secondary meridian or split between both.