I have been myopic since childhood. The power gradually increased to -6 diopters before it stabilized. Now I am 65 and it has for some reason decreased by about 1diopter. I needed bifocals when I was close to 50. As I was a desk worker, I used to wear what they call executive bifocals. These lenses are divided into two distinct parts across the middle - upper half for distance vision and the lower half for near vision. Kids would often ask why was I wearing glasses that had a crack! Working on a computer was a challenge with this pair. It would lead to a pain in the neck if you looked at the monitor through the lower half.
So I had a pair of monofocals made for 'intermediate' vision with a power lying between the two in the bifocals. Often I would make do with the monofocals throughout the day and reach for the bifocals only when going out for a walk or a drive. The monofocals would make do even for driving and walking during bright daylight.
The last time I had my glasses made the optician advised that instead of carrying two pairs, I should go for the progressive lenses which would serve for all three purposes, namely, distance, near and intermediate vision. However my search on the internet brought out that progressive lenses have zones which make peripheral vision distorted. It said that many professionals, particularly pilots, often reverted to bifocals because of this problem. So I ignored the advice.
Then as luck would have it, I lost my intermediate vision glasses during a trip to Delhi. I put my apprehensions aside and visited my optician for making me a pair of progressive glasses. When I wore the glasses for the first time I experienced and realized what was meant by the blurry zones of intermediate vision. I chose to wear my bifocals for driving back home.
As recommended by the optician I kept on wearing the progressive lenses throughout the day. After a week I feel I am quite accustomed to it now and here are my findings. The glasses work quite well outdoors when it is bright and sunny. However when it is not so bright or you are indoors with subdued lighting, the distortions get amplified. The peripheral distortion zones do leave two narrow strips, one at the top and one at the bottom, free of distortion. So when you are looking at a distant object through the top narrow strip or looking at a book through the bottom narrow strip there is little problem. For intermediate vision, which mostly means working on a computer, you must train yourself to look through the narrow vertical strips towards the nose on either side. Distortions arise if you are not looking straight at the screen. If your head is tilted even a little on one side, one eye starts looking through the blur zone and discomfort starts.
Another problem is watching TV while reclining on your bed. In a reclining position you have to look through the lower part of the two lenses which are meant for reading. So you have to sit up a bit and / or tilt your neck a little forward so that you look through the upper part.
Yet, it offers a huge advantage of not having to switch your spectacles. I do hope that my eyes will acquire the discipline of looking through the correct zone and the visual cortex will learn not to mind the distortions when the eyes err!
Before I close, I must add that the distortions that we talked about are much more severe than the normal distortions at the periphery in monofocal lenses.
The last time I had my glasses made the optician advised that instead of carrying two pairs, I should go for the progressive lenses which would serve for all three purposes, namely, distance, near and intermediate vision. However my search on the internet brought out that progressive lenses have zones which make peripheral vision distorted. It said that many professionals, particularly pilots, often reverted to bifocals because of this problem. So I ignored the advice.
Then as luck would have it, I lost my intermediate vision glasses during a trip to Delhi. I put my apprehensions aside and visited my optician for making me a pair of progressive glasses. When I wore the glasses for the first time I experienced and realized what was meant by the blurry zones of intermediate vision. I chose to wear my bifocals for driving back home.
As recommended by the optician I kept on wearing the progressive lenses throughout the day. After a week I feel I am quite accustomed to it now and here are my findings. The glasses work quite well outdoors when it is bright and sunny. However when it is not so bright or you are indoors with subdued lighting, the distortions get amplified. The peripheral distortion zones do leave two narrow strips, one at the top and one at the bottom, free of distortion. So when you are looking at a distant object through the top narrow strip or looking at a book through the bottom narrow strip there is little problem. For intermediate vision, which mostly means working on a computer, you must train yourself to look through the narrow vertical strips towards the nose on either side. Distortions arise if you are not looking straight at the screen. If your head is tilted even a little on one side, one eye starts looking through the blur zone and discomfort starts.
Another problem is watching TV while reclining on your bed. In a reclining position you have to look through the lower part of the two lenses which are meant for reading. So you have to sit up a bit and / or tilt your neck a little forward so that you look through the upper part.
Yet, it offers a huge advantage of not having to switch your spectacles. I do hope that my eyes will acquire the discipline of looking through the correct zone and the visual cortex will learn not to mind the distortions when the eyes err!
Before I close, I must add that the distortions that we talked about are much more severe than the normal distortions at the periphery in monofocal lenses.
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