Saturday, November 04, 2006

On bifocalism

Well, I've had my working glasses for a week now, and am getting used to them. The spread of focusing distances is much greater than I remembered ordering, but perhaps this is an effect of the lens-grinding technology. Right at the upper rim, I can see clearly up to about 1.2 metres away; at the lower rim I can focus down to book-holding-distance of 40cm - at which distance I don't need glasses anyway. The effect is that I can walk around well-known environments (the office, home) without changing glasses, as soon as I get within reach (or trip-over) of something, I can see clearly (enough) to grasp (or avoid) it.

In the first few days, I had problems when looking left or right of centre. There is a much greater refraction effect than in my distance glasses, and I would have a twinge of nausea if I looked too abruptly to the side. That has disappeared, I cannot now remember whether the problem occurred when I moved my head or my eyes.

When one hears bifocals described, they sound ridiculous: "What, you have to tilt your head back to read that, then drop your chin down to read this?" While this is true, the motion is much smaller and less disturbing than one thinks. Old-style bifocals, with a clearly defined break in the middle, were a simple way of wearing two sets of lenses at once; wearers of these did indeed need to move their heads up and down by a significant distance. Modern bifocals are what you might call "sliding focus" meaning that there is no division between areas, the lenses are smoothly and continuously ground. There is in theory a spot in my glasses which is perfectly focussed for 51.382 centimetres, somewhere between nominal "40" and nominal "60."

And (at least in my case, only -2 diopters to be remedied) the differences aren't that great. I am looking at a sentence on a piece of paper behind the laptop's screen, 65cm away, and can force my eyes to focus there through any part of the lenses. It is a strain, yes - and the body learns to avoid strain. I noticed that I move my head my head moved slightly to bring this sentence into the upper middle of the lens, where the least strain is. The point is, it's automatic: after a week I no more think about moving my head to refocus my eyes, than I do about finding the right spot for my hands on this keyboard. It just happens.

The bifocal effect (things nearby are seen in the lower part of the lens, things distant are seen in the upper part) made me think of traditional Japanese scroll paintings, where a similar effect is used: the upper parts of the painting are in the far distance, the lowest part is closest to the viewer. I had always thought that this was just an odd convention, but wearing these glasses has made me understand it: the scrolls were painted - and intended to be viewed - lying flat on a table. In this case the artistic convention conforms to physical reality: the "close-up" lower parts really are closer to the viewer, the "distant" upper parts really are farther away.

Public service announcement #5 These glasses cost around 300 Euros including frames. Now, I'd be the first to admit that they are neither hip nor cool, GQ will not be sending a photographer around; but neither are they ugly, small children don't cry and dogs don't bark. They're just perfectly normal bifocals for 300 Euros.

Ageing Yuppie recently bought a pair of bifocals for 950 Euros. Slim recently bought a pair of plain-vanilla distance glasses for over 500 Euros.

Well, that is in my opinion just craziness. In case any other readers in Stuttgart want a reasonably-priced pair of glasses, I recommend Optik Maier, Silberburgstrasse 102 (no website, how quaint).

Four down, twenty-six to go.


Blogger Savtadotty said...

The brain, she is a wondrous friend.

November 4, 2006 at 10:21:00 AM GMT+1  
Anonymous noorster said...

That is still my monthly rent in glasses!
When I was a kid I once asked my grandma (who had one of those split-lense bifocals), "What, you don't see anything without these?!?" Later TPTB punished me by making me need -5.00 dioptre glasses/contacts (I really don't see anything without them.)

November 4, 2006 at 3:44:00 PM GMT+1  
Blogger Mary Beth said...

I tried a pair of the no-line "progressive" bifocals when I first went to needing them. The progressive part was where I marched back to the eyeglass store and demanded my money back! Geesh, so instead of tilting my head up and down a bit, I had to turn my whole head every time I wanted to see anything, because of that very small sweet spot in the middle. Um no thank you. Now I have straight bifocals and a set of prescription reading glasses for times when I'm doing prolonged computer or close work. Much better.

Coming to you from te NaBloPoMo! randomizer.

November 4, 2006 at 4:22:00 PM GMT+1  
Anonymous May said...

For some reason, this post sounds a bit melancholic to me - reminds me that we're all getting older. But I guess that talking about the passing of time is better than to pretend that it doesn't happen.

Now I'll read some more of your posts...

November 4, 2006 at 7:47:00 PM GMT+1  
Blogger brooksba said...

Someday, I figure bifocals will adorn my face so I appreciate the description of your experience. Glad to hear you did get a bargain on them and that you're getting used to them. Savtadotty is right - the brain is wondrous.

November 4, 2006 at 9:23:00 PM GMT+1  
Blogger Udge said...

May: melancholic? I can't see it myself, unless you consider addressing reality to be in itself a form of melancholy.

MaryBeth: I assume that this was some time back, and that technology has changed since then, because there is no "sweet spot" on mine. I can see well (at the various appropriate distances) through all of the lens except the far corners (the nausea thing).

Noorster: yeah, even the cheap ones are expensive in real terms. -5 is pretty strong stuff!

Savtadotty & Brooksba: nature intended for us to repair ourselves on the go!

November 5, 2006 at 4:51:00 PM GMT+1  
Blogger JoeinVegas said...

No, not twenty six to go, the idea is to change you so that you get used to it, and keep doing it every day.
I had progressives, then went in for Lasic - first time in forever I can drive without glasses (used to be really thick ones). Now I need them for close up, which used to be good.

November 5, 2006 at 7:59:00 PM GMT+1  

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