This was obviously not a surprise to people who know about these things, but it was to me and I want to share. I was having a problem with my “good eye” (the one that currently does not have an oil drop–which will come out later this year-to hold the retina against the eyeball). It was getting hazy and quite suddenly I was unable to read. During the examination, I was asked to try an eyechart. I had one of those “flattened spoons” over my other eye and could not get below the third line of the chart. Then he gave me what at first glance looked like another spoon and asked me to hold it over the eye being tested. This spoon turned out have about 40 or 50 pinholes in it. When I held it over my eye, suddenly my vision cleared enormously. Although the light level was seriously less, I was able to go many lines down the chart. Now I know about small apertures and focal length, but I was unaware that 40 pinholes could be combined in that way and my problem wasn’t focus anyway. What it was was something they called posterior capsular opactification. What that meant was a cloudy membrane had formed behind my artificial lens and two minutes of laser therapy cleared it almost instantly. Yay, I can read again. Can’t wait till the oil drop comes out.
But I was–and remain–astonished by the optical effect of those tiny pinholes.
You mean the future where I’m reading this with a pair of very light, mild-correction desk glasses (worn only to keep the strain of hours of this crap down, not from 100% need) instead of peering at it through the bottoms of two old-fashioned glasses?
The holes were maybe 1/8" apart. Yes, the laser treatment was miraculous. I knew will what one pinhole lens could do. What blew my mind was the fact that 50 of them would combine as they did. Also, stronger reading glasses would not help (I tried one of my wife’s), but these many pinholes had a remarkable effect.
This has been known for a long time. Aristotle wrote about using tubes (not pinholes) to “correct” vision. (Some people make the claim that Aristotle and others knew about the pinhole effect from the camera obscura effect, but that’s something completely different).
I suspect (and have suggested in print) that pinhole “glasses” were in use in the ancient world. It’s an easy effect to discover, and the pinholes can be fabricated from any tough material – ceramic, seas shell, leather, stone, woopd, etc. The devices probably wouldn’t look like “glasses”, but might be in the form of a “monocle” or a “lorgnette”. They’d be a helluva lot easier to fabricate than glass or crystal lenses. Have they been found? Who knows? They’d look like discs or paddles with holes in them. Lots of things like thios have been found (I’ve located some), but how could you tell if they were ever used as pinhole viewers?
There have been claims of pinhole glasses that actuall look like pinhole glasses, from India, but the proponents of these never give locations or dates. Having traced them myself, I think the location is wrong – these appear so similar to items found in Central Asian Chinese tombs* (probably from circa 800 AD) that I think the identificationm of the origin in India is mistaken. Some people think these werre simply decorative things, but they were fouind on the eyes of the deceased, and they work. Think they were just burying people with their effective eyewear.
Pinhole glasses have beenb patented sebveral times since the late 19th century. Sthenopeic pupils (as they are often called) used to be used for eye conditions where no good corrective glasses existed (sorta like the OP’s situation).
A back issue of a Hiking magazine (Backpacker for June 2007, p. 54) suggests making your opwn pinhole glasses if you’re nearsighted and lose or break your glasses while on a hike. Or you could do it if you’re Burgess Meredith with broken glasses in a postapocalyptic world, and you have a lot of reading to do.
The glasses reduce input light, so you’re trading light for clarity of vision
The claim that this increases eye strain seems odd – these glasses reduce the strain induced by squinting. When you wear these, you don’t have to squint.
I have a book containing this, and other weird Optics stuff, coming out in August.
*specifically, the Xinjiang Uygur Autonomous Region. T’ang dynassty tombs in the Astana region of Turfan, in case you’re wondering.
