The mission: Supermarket shopping without spectacles but with lots of baked beans? It's all a bit of a blur for Matthew Sweet

I was 15 when I got my first pair of glasses. It was a shocking experience. Not because of their oblong, fake-gold Bamber Gascoigne-ish naffness - which, for some reason, I found winningly attractive - but because of what I saw through them. Every leaf had a separate identity. Hedges were not just vague green mounds but bundles of distinct little privet leaves. I had thought the world was an Impressionist sort of a place. In that moment, I knew it was a mess of Pre-Raphaelite detail.

Since then, my short-sightedness has got worse, and I've switched to wearing contact lenses or a pair of round plastic tortoiseshell specs (bought in 1990 because I thought they would make me look like Peter Davison in Campion). So this week's mission should be the large-print edition. I've spent the last week engaging with the world without a perceptual truss. So I'm sitting at my computer, writing this in a point-size which means I can only get three words on the screen at once. It's been a tough week.

When you leave the house and enter the blurry, murky, unmagnified world, a number of thoughts occur to you. Will I get run over by a milk float? Will I snub my friends on the street? Will I accidentally buy the kind of spaghetti hoops that have small frankfurter sausages already in the tin? This last one was too important not to put to the test.

An unfocused trip to Lewisham Tesco's is a terrifying experience. Especially for the people whose feet I ran over with my trolley. My main problem was not the danger of making a Mr Magoo-like mistake. It was the extra effort required in deciding what I was looking at, and the self-consciousness I felt in expending it. Because the rows of packets all seemed much the same, I had to blink and squint to see what they contained. And navigation was intensely difficult. The signs were too high in the air for me to read, so when I bumped into a staple all-rounder like baked beans, I felt like a conquistador stumbling upon El Dorado.

Getting to the right till was a bigger challenge. "I'm sorry, this is 10 items or less," said the woman at the checkout, pointing to a gigantic blurred rectangle hanging over her head. "I'm very sorry," I said, leaning forward and trying to make out the name on the badge on her right breast. "I'm very sorry, Jacqui." I'm sure she appreciated this personal touch. When I got home my partner, Nicola, said, "Why have you bought eight tins of beans?"

That evening, Nicola helped me down to our local multiplex for a screening of Hilary and Jackie. If you haven't seen it, it's a film about two blurry women who don't really like each other very much. As I understood it, one of the blurs wanted to sleep with the other one's indistinct husband. One blur was a cello player, I think. At least, she was jiggering about with a stick and there was a lot of Elgar on the soundtrack. Possibly the director had given melodramatic over-emphasis to a scene in which she was unblocking a sink or retrieving a sock from behind a radiator with a piece of dowling, but my money's on the cello. Anyway, not being able to see any of this very well was quite instructive. "The script was certainly very bad," I said to Nicola as I held open the exit door for her. "What did you think?" "Why do you want me to go into the gents?" she replied.

At least I said it to her, and not the fire extinguisher