Comments on: What tool did the optometrist use?

Question: What tool did the optometrist use?

Pantengliopoli — Tue, 03 Mar 2009 09:30:07 -0800

What did the optometrist use to make my vision so much better, and how does it work?

Not the fancy bells/whistle machine with all the cool gears and lenses. Before that, he used a simple piece of plastic to block one eye and leave a hole for the other. After testing vision with that, he flipped a second piece of plastic over the hole -- from what I could tell, the second piece was just a thin sheet of opaque plastic with a bunch of small holes in it. No lenses or anything, just little holes.

With that covering my eye, I could see the smaller print much more clearly. How does that work? Does it replicate the eye squinting by reducing visual "noise" or something? I'm fascinated.

By: tomierna

tomierna — Tue, 03 Mar 2009 09:34:36 -0800

Like a camera lens, the smaller the aperture, the wider the depth of field.

By making the aperture of the iris of your eye as small as a pinhole camera, most everything will be in focus.

By: Pantengliopoli

Pantengliopoli — Tue, 03 Mar 2009 09:39:40 -0800

That's amazing... I've never really understood depth of field or how it works wrt the aperture.

By: luciaisdada

lucia__is__dada — Tue, 03 Mar 2009 09:47:07 -0800

Actually, my mother was telling me about these. Pinhole glasses is the googling term you need for further info. Thanks for reminding me to look them up.

By: MrMoonPie

MrMoonPie — Tue, 03 Mar 2009 10:06:42 -0800

Google pinhole magnifier for more detail.

By: cowbellemoo

cowbellemoo — Tue, 03 Mar 2009 10:13:03 -0800

I can't read anything beyond 1ft without glasses, but if I need to read my alarm dial in the middle of the night, I make a small hole with my fingertips to see through. Then I can read the blur!

By: JackFlash

JackFlash — Tue, 03 Mar 2009 10:45:27 -0800

People instinctively squint their eyes when straining to see something better. Making a slit with your eyelids reduces the aperture of the eye, improving visual acuity.

The optometrist uses the pinhole test to determine the underlying visual acuity of your retina despite refractive problems with your cornea or lens.

By: Pantengliopoli

Pantengliopoli — Tue, 03 Mar 2009 11:04:57 -0800

Wow -- that's just fascinating. I had no idea -- thanks everyone. I'll be making little circles with my fingers and staring at stuff for the rest of the day.

By: willmize

willmize — Tue, 03 Mar 2009 11:37:55 -0800

Pinhole glasses are also used in the Bates Vision Improvement Method. More info here.

By: paulg

paulg — Tue, 03 Mar 2009 18:55:55 -0800

JackFlash is correct. The tiny hole means you're using a much smaller bit of your cornea. It's sort of like if you look at a fun house mirror from ten feet away the mirror makes you look really tall or really fat, but if you look at the mirror from an inch away the bit you can see isn't very distorted.

Comments on: What tool did the optometrist use?

Question: What tool did the optometrist use?

By: tomierna

By: Pantengliopoli

By: lucia__is__dada

By: MrMoonPie

By: cowbellemoo

By: JackFlash

By: Pantengliopoli

By: willmize

By: paulg

By: luciaisdada