My binocular vision since my eye operations occasionally presents problems. It is not quite what it used to be. I had to work hard for a time after the final operation to fuse the images from both eyes once again – my brain had slipped out of earlier habits after the years when I was dependent on the vision of only one eye at a time. After my spell of monocular vision, binocular vision only came back with training.

When I get fatigued, even now, the images tend to drift apart and require a constant effort to superimpose them again. But when I'm watching some rubbishy programme on late-night TV, this is a convenient warning to give it up !

For the life of me, I can't fuse the red/green images of the many stereo images in Richard Gregory's book The Intelligent Eye – I thought at first that I had a faulty copy and the red/green printings were displaced at too great a distance on the page for me to resolve from a comfortable distance.

Eventually, I decided it must be me – it's some quirk of post-cataract optics, focal distance complications caused by my dependence on external positive lenses to focus the images on my retinas...

But, curiously, your drawing and spectacles work for me ! ■

 
Letter to Diego Uribe, January 1985

On the matter of bifocals, I can report that for 99% of the time I find the reading lens line is completely invisible, the transition from distance to reading mode occurring without a hitch. I may have mentioned that I got the bifocals after attending a Russian class at [Manchester] university, where the tutor wrote out lots of words on the blackboard, which we were supposed to copy.

I was hindered in this because I needed my long-distance specs to read the blackboard, and then change to my reading specs to write it out in my notebook. The distraction of switching specs slowed me disastrously. The tutor having reached the bottom of the board proceeded to clean off the top half, and start out on another sequence. I just couldn't keep up.

By the time I got my bifocals the Russian class had been dropped because of lack of support. That's life. However, once I'd got used to them, the bifocals more-or-less became a permanent fixture, and my reading and distance specs have just collected dust, and been kept on hand for emergencies. There didn't seem to be any need for the refinement of varifocals until I hit this "in-between" situation as an onlooker at the computer. But I guess that occasional disadvantage hardly justifies the outlay on varifocals.

It was a source of considerable amazement to me, immediately after my operations, when I was coping with temporary lenses, how eye and brain adapt and correct distortions. Initially, I had great difficulty in assessing distances because of the magnification of the simple lenses I was given; things always turned out to be further away than they seemed, and it was hell coming down stairs. And the sides of doorways curved in alarmingly, so that I felt I needed to squeeze through.

Then vision adjusted as the learning process took over, and the doors miraculously straightened out, and an outstretched hand actually made contact with an object instead of stopping some inches in front. I learned to see what I expected to see, again. Mind you, If I lift up my glasses and look floorwards, my feet now seem such a long way off, I feel quite giddy! The rooms in the house seem smaller, and I can only get a sense of the true perspective (though blurred!) when I remove my specs.

About the only time I return to reading specs these days, is if I'm doing a big drawing and an all-over field of clear vision saves me wagging my head about unduly. Otherwise, I wear the bifocals all day. (I don't need them at night as my vision in dreams ins 20/20: don't recall ever wearing specs in my dreams). ■

 
Letter to Fran & Brian Varley, end of June 1997

On this matter of moving your head around to help with reading, I suppose I do it automatically when wearing the bifocals, to adjust different situations. I become more aware of it when, for example, I'm reading [from] the copyboard on the left of the monitor, and keep glancing over periodically to the screen to check on my keyboarding. At such times, I become aware of the restricted field of the "reading window" on the bifocals, and hurriedly change to reading specs, to cut down on unnecessary movement and make life easier...

With either specs I can accommodate a line length of text without any noticeable head movement, though if I try to use my left eye solo, I am hindered by a central blind spot (which just about covers an individual letter) as my eye travels along the line. Fortunately, this defect is not apparent when I use both eyes together...

My main complaint is the loss of peripheral vision after the operations. I find it difficult to walk alongside anyone; it's disconcerting when you're trying to carry on a conversation if you can't keep track of your companion's position. And when I need to cross the road, I have to look squarely in each direction, and then do a quick last-minute check before making a dash: crossing a junction, where a glance over your shoulder as well as in both directions is essential, can get me too dizzy to start off in confidence! ■

 
Letter to Fran & Brian Varley, September 1997, during Di-Mania