Re: Presbyopia

Feb 27, 2008 3 Replies


When I get my lenses replaced, I want to be focussed at about 10". I


> think they can do that.
>
> John

That's a request would for about -3 diopters [1]. The pre-op measurement isn't ultra precise, so results vary--my impression is that lens replacement tolerances are about +/- 1 diopter.


I'd shoot for -2, myself. Certainly not 0.0--I want to be able to see nearby things--like my glasses--without needing glasses!


[1] Your prescription is for the focal length of _the lens needed to correct you_ for distance vision (focus at infinity), given as 1/ (focal length in meters). Myopes are corrected by concave lenses, hence the "-".

Cheers, James Arthur


[snip]

My replacement was dead-on. Over time, however, it has tilted a bit, giving me some slight astigmatism.

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave

That's a damn good result. My mom's were within 0.5 diopters of target, IIRC, and corrected her a darn sight better than the original equipment.

The problem is not so much the doctors, AFAICT, just the vagaries of measuring the optical properties of ... um, meat. Live, wiggling, pulsing, transparent meat at that.

Cheers, James Arthur

My eye people, Barnet Dulaney Perkins (Phoenix), dilated and numbed me so I couldn't move my eyeball, then took a topographical photo of the retina, which was automatically analyzed by computer to size the implant... amazing medicine now-a-days!

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required