Wednesday, June 13th 2012
For health reasons, Tigger and I both qualify for free sight tests annually. My optician is Mr Shah, a discreet and courteous gentleman who always remembers me and enquires after my interest in photography.
Every year he sends me a letter reminding me that it is again time for my annual sight test and every year I keep putting off making an appointment until nearly another year has passed.
At each of the last several meetings, Mr Shah has carefully examined my eyes, required me to read from the distance chart and from the hand-held card and then pronounced himself satisfied with things as they are. One of Mr Shah admirable features is that he does not seek to sell you new spectacles without a real need for this, unlike certain high street opticians’ stores I could mention.
What finally prompted me this time to make the appointment was that I was finding it more difficult than before to read small print or see the detail in things.
When we watch a video together, we usually run the “Subtitles for hard of hearing” when these exist as otherwise my hearing sometimes misses important bits of dialogue. For some time I have had difficulty reading these subtitles without scrunching up my eyes.
Mr Shah confirmed my diagnostics and even he was surprised at the degree of change in my eyes and the speed at which it has come about, especially after a long period of stability.
I first started wearing spectacles, for reading only, when I was in the sixth form. For a number of years, that remained the case. Then I began having difficult with my distance vision and was prescribed a second pair of spectacles which I wore for driving or for watching TV. That situation remained, with occasional slight lens changes, until about a decade ago when, after an eye test, an optician told me I no longer needed my distance specs and that I was “legal to drive”. I still do not wear glasses for distance vision though I am aware that my visual acuity is less now than when I first stopped wearing them. As I no longer drive, though, it does not seem necessary to bother with them.
For reading or working at the computer, however, it is a different matter. What Mr Shah discovered was that whereas my right eye is long-sighted, my left has become very short-signed. “It is your right eye,” he said, “that is doing all the work.”
So after half a decade or so, I suddenly need new specs. Worse still, a single pair will not suffice as I will need one pair for reading and the computer and another pair for “middle distance”, that is, to allow me to read the subtitles on DVDs. The good news is that the latter specs will be useful, according to Mr Shah, for viewing museum displays and art exhibitions. At the moment, I have to put on my reading specs to read the labels and take them off again to view the picture or sculpture.
I had of course taken my current spectacles with me but, unfortunately, Mr Shah quickly diagnosed that they had reached the point where their joints were perilously worn and would soon fail. I would need to buy new ones. Such an expense is unwelcome at any time but there is no alternative and one’s eyesight is a precious gift that deserves to be looked after properly.
I am looking forward to being able to read small print again without screwing up my eyes and also to being able to read DVD subtitles. The thought does cross my mind, however, that if my eyes have changed so suddenly now, they might do so again, even before the end of the customary year between sight tests.
On a different but related topic, I was one day playing about with pieces of cardboard and pins. I discovered that if you view a scene or a page of print through a small hole, the scene appears in focus even without the observer wearing corrective lenses. This, of course, is the principle of the “pin-hole camera” that takes sharp photos without a lens.
It therefore occurs to me to wonder whether it would be possible produce a sheet of some opaque material pierced by thousands of closely packed small holes and whether this material could then be used in spectacles as a sort of universal correcting device, obviating the need for expensive transparent lenses.
There are probably good reasons why this would not work. Can anyone explain (simply, if possible!) what these are?
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I seem to recall an etched lens from decades ago (something akin to Fresnel, I think, or maybe concentric rings focussing an image from all depths of field) that was supposed to be the basis for a new universal lens. Not sure whatever happened to it – it featured on Tomorrow’s World.
As I recall, the pinhole requires a high level of illumination to work, making it unsuitable for low light levels (or night-time).
I grant that a sheet pierced with holes by old technology would reduce the transmission of light but with modern technology and fractal techniques, one could reduce the solid matrix to any arbitrary level (leaving enough, of course, to ensure sufficient rigidity).
I remember a number of inventions that appeared on Tomorrow’s World and were forecast as world-savers and then sank without trace.
There’s an interesting new camera design (you’ve probably seen it already, but just in case: http://www.lytro.com) that holds out the interesting possibility of being able to have virtually infinite depth of field – AFTER the photo has been taken.
I wondered whether the same technology could be applied to prescription lenses (so you’d be having an image projected onto your retina by the camera/lens, suitably miniaturised of course
). One pair of glasses for all needs – and not varifocals, either…
I read somewhere about the possibility of post hoc refocusing but had not encountered this specific product. It looks very interesting and I can imagine it quickly finding a place in what is currently the cheaper compact market. The camera itself is not yet good enough for professionals and serious amateurs and it remains to be seen whether the technology can be scaled up to achieve the requisite picture quality without becoming prohibitively expensive or unwieldy.
Where it would be very useful for me would be in photographing fast moving insects such as bees. You don’t have time to focus manually but when you do fire off a shot, the camera often focuses on foliage instead of the bee! Being able to change the focus afterwards would be a boon.
I think spectacles are also due for some new development. At the moment they are what you might call “dead lenses”, that is, they have fixed focus, and what you need are “live lenses”, capable of changing focus according to environmental conditions and feedback from the wearer.
There are “liquid” lenses that might fit the bill – they’re being incorporated into cellphone cameras and I guess they might work for spectacles. http://www.varioptic.com is one provider.
Quite possibly. All the good stuff seems to be going in in the arena of cameras, phones and tablets. It;s about time that spectacle wearers got some love as well!
I remember seeing such glasses in junk shops in Liverpool, but I think that they were some sort of primitive sunglasses.
I realised that my eyes were going when I could no longer read sauce bottles – I’m slowly sliding into Shakespeare’s sixth age;
The sixth age shifts
Into the lean (I wish!)and slipper’d pantaloon,
With spectacles on nose, and pouch on side,
His youthful hose well sav’d, a world too wide,
For his shrunk shank, and his big manly voice,
Turning again towards childish treble, pipes
And whistles in his sound. Last scene of all,
That ends this strange eventful history,
Is second childishness and mere oblivion,
Sans teeth, sans eyes, sans taste, sans everything.
In the shops these days there are plastic slatted specs though whether these are for sun protection or for “style” I do not know.
Shakespeare knew a thing or two about life but tended to express things in a somewhat dramatic tone – only to be expected, of course.
Among the many useful things I carry around with me in my handbag (along with the folding scissors and the anti-bacterial handwash) is a folding magnifying glass. Sauce bottles cannot hide theIr secrets from me.
The lens of the eye is ringed with muscles which focus vision by contracting to thin the lens or relaxing to thicken it. The lens tends to “sclerose” (harden) with age, which eventually leads to a form of cataracts called “nuclear sclerosis” cataracts. As the lens scleroses, it becomes less flexible and visual acuity suffers (“presbyopia”). Everyone eventually gets cataracts — it’s merely a function of living long enough. However, some people’s lenses sclerose more slowly than others to the point that they succumb to old age before their lenses reach the point of needing surgery. I wonder that you have to use two sets of glasses. Can you not obtain bifocal lenses? I have lineless trifocals, which I adore, with the middle “focal” specifically ground for computer distance (I actually measured the distance from eye to screen so that my ophthalmologist could make the prescription.) I still read “dead tree edition” books better without my glasses than with them, but when I’m using my reading table to read my Kindle, I do so with my glasses on. The one quibble I have with my lineless trifocals is that they do slightly distort one’s peripheral vision. However, my previous pair of trifocals had lines, and it became quite annoying always to have to be canting my head up and down in order to “center” the object I was trying to view between the lines of the “focals.” This new pair also have frames which feature a separate set of “clip on” type sunglass lenses that are held to the glasses frames by magnets located beside the hinges. (http://www.jcpenneyoptical.com/productswomen-easyclip.html# ) . I think they are the bees knees.
As the new spectacles are for close work and mid-distance, respectively, which are two well defined sets of activities, I don’t think bifocals are particularly indicated.
In the days when I needed distance and reading spectacles, I commissioned a pair of varifocals. They were dreadful. It was like looking through a keyhole and to read even a small page like that of a paperback book, I had to move my head from side to side – a whole line of text would not fit within the field of vision.
Such spectacles also have the problem that you have to look through a specific area of the lens to see a particular distance. Try looking down a stairwell, for example, and you have to bend your neck at a ridiculous angle, The same is true if you want to read a notice in a high position.