What tool do optometrists use?

June 15, 2007 1:29 PM

What are those things called that optometrists use to determine your prescription, and how do they work? (The ones where they say, "Which looks better, this... or this?")
posted by smackfu to health (9 comments total)

Phoropter.
posted by cobaltnine at 1:33 PM on June 15, 2007

In grand AskMeFi tradition, I don't know the answer, but I have something to say about it anyway. :-)

I've worn glasses so ~30 years, so I've been visiting optometrists fairly regularly for a while now. Over the past years, it seems like the use of the "phoropter" (you rock, cobaltnine) has diminished greatly. Now there's some largish (1 meter cubed?) box you place your face against and a compuetr flashes lights at you for several seconds and then spits out a spool of tape with your prescription. The optomotrist still puts you in the chair for a bit of "Which do you like best, 1 or 2?", but it's a much shorter experience, as if the computer's output is simply being confirmed.

Anyone else noticing that trend as well? Any student optometrists in the audience who want to chime in?
posted by browse at 6:49 PM on June 15, 2007

Think of the phoropter as a pair of glasses that can be adjusted to any prescription. It contains lots of lenses and is designed so that your optometrist can easily switch from one to another. By asking you "Which looks better, this... or this?" your op is narrowing it down to the combination of lenses that best correct your vision. Op then looks to see what that is, and writes your eyeglass prescription accordingly.
posted by exphysicist345 at 9:30 PM on June 15, 2007

browse: Yes, I've noticed the same thing, and my eye doctor said "the machine is very accurate, I just like to double-check it."
posted by Ynoxas at 10:29 PM on June 15, 2007

Interesting. I've never seen this 'phoropter' nor the computer flashy box. My people have always used a big case of individual lenses (like this), which they slot into a pair of these adjustable eyeglasses. Is that just like a phoropter, but in kit form?
posted by chrismear at 2:05 AM on June 16, 2007

Anyone have a name for the "computer flashy box?" I'd like to be able to ask for it when I look for a new optometrist.
posted by feloniousmonk at 6:42 PM on June 17, 2007

chrismear: I've only seen that once... my eye doctor has the computer flashy thing and the phoropter, and he made up one of those so I could walk outside and look around after having a particular difficulty getting my prescription just right.

feloniousmonk: i don't know the name of it, but I strongly suggest using a doc that has one. My wife has profoundly poor vision, and was perpetually disappointed with her perscriptions, until we got married and she went to my eye doctor. He gave her the best prescription she'd ever had because the computer flashy thing did the heavy lifting.

To make sure I'm clear, you look into it, and it brings a design in and out of focus, and is somewhat noisy.

When you are finished, it actually spits out what your prescription should be. It usually gets you 95% of the way there, and then the doc just "fine tunes" with the phoropter.

It's borderline magic. And it also VASTLY reduces the amount of time going "Ok, which one looks better, #1 or #2" "Uh... they look the same".

God I hate that. There are many times I simply cannot see a difference.
posted by Ynoxas at 10:31 AM on June 18, 2007

I think that's what they're talking about here in the wikipedia article: "Sometimes a retinoscope or an automated refractor is used to provide initial settings for the phoropter."

They also have a neat machine that can read the prescription off a pair of glasses, which they can use for the same purpose, or to see if the lab screws up a prescription.
posted by smackfu at 10:32 AM on June 18, 2007

Retinoscope seems to be a good tip. Thanks! (TMI!) I pass out after too many sessions of "how about this one?" so it's a big help to cut that down.
posted by feloniousmonk at 6:47 PM on June 18, 2007