For at least a decade I’ve been telling anyone who would listen that I wanted to end my days in California. One of the people I said this to, in San Francisco, was quick to put me right: you don’t end your days in California, you begin them. I was happy to be corrected in this distinctly Californian way, but when we eventually got here it seemed that I might have been right after all.

My wife and I moved to Venice Beach in mid-January. The timing was perfect: England was sinking beneath the waves, or the rivers at any rate, but the weather here, even by the high standards of Los Angeles, was wonderful. We quickly established a routine: at eight o’clock we’d go for coffee – an eight-ounce cappuccino, extra hot, please – and a twice-baked hazelnut croissant at Intelligentsia. My wife would cycle to her office in Culver City, and I would go home and work. Every other afternoon, I’d cycle down to the tennis courts by the beach, play for an hour and ride home as the sun was setting over the Pacific.

Then, only ten days into our new life, I bent down to push some rubbish into the already stuffed bin. When I stood up half the world had disappeared. It had disappeared but it was still there, sort of. The kitchen wall was visible but it didn’t seem quite right: familiar but changed, as happens in dreams. Ah, now here was something I recognised: a strip of brown wood against the pale yellow wall. It was the frame of the mirror: I was looking into a mirror but, like a vampire, I couldn’t see my reflection. The mirror had become a window, but all that could be seen in this window was the wall on the other side of the room, behind me or behind where I used to be. Where had I gone?

‘Something’s happened to my eye,’ I called out to my wife. She was in the bedroom but she too had semi-disappeared. I could see half of her body but her face had gone. I thumped myself lightly on the side of the head as if that might knock everything back into place, dislodge the opaque filter that had come between me – though even the idea of there being a me had become less certain than usual – and the world. I was getting confused as I tried to make sense of this insubstantial world in which things were and were not.

‘What’s happening?’ she said.

I was covering up one eye and then the other, trying to eliminate variables, as one does with an electrical fault (bulb, fuse, socket …) to ascertain where the problem lay, which part of my sight had gone.

‘I seem to be blind in one eye, the left, but I can sort of see out of it. Where have you gone?’

‘I’m here.’

‘So why are you just hallway?’

My wife has often had problems with her eyes. Three weeks earlier, before I’d even arrived in California, she’d gone to the ophthalmology department of the hospital with an ulcer on her cornea. That’s where we should go now, she said. She called and made an appointment. They could see us at 9.30. It was 8.30 now, and it would take twenty minutes to get there in a taxi. Which meant there was time to do what we did every morning: go to Intelligentsia for our eight-ounce cappuccinos and twice-baked hazelnut croissants which were not as nice as the doughnuts I’d had every day when we’d lived in New York for four months the previous autumn but which had become part of our unchangeable routine. Getting ready took longer than usual. I kept asking where the thing was, the thing that I kept my health insurance and credit cards in, the card-holder thing. And my keys. As soon as she told me I would ask about something else and by then I wasn’t sure whether I’d picked up my cards and my keys and I’d be wondering if I needed my passport and it would turn out that I had my keys in my hand and my credit cards in my pocket. It took ten minutes to get out of the house, during which time my wife’s patience quickly frayed. It was, she said, like dealing with a cross between a half-senile pensioner and a totally monged-out teenager.

We walked to the café. I held on to my wife’s arm. The sidewalk was the sidewalk and the road was the road. There were people and cars, brilliant sunshine, colours. We waited in line and ordered the same things we ordered every day. We ate and drank as usual and some of the world seemed to have come back. It was more like, as my mum used to say of people with mental trouble, I was not all there.

Our taxi arrived and we were soon speeding along Venice Boulevard. I could now see something out of my left eye but I had no peripheral vision.

At the hospital a nurse immediately gave me drops to dilate my pupils so the ophthalmologist could take a look. As a result, my vision, having improved slightly in the taxi, became distorted in both eyes. The world which had brightened out almost to non-existence became brighter still. The ophthalmologist did simple tests, covering up one eye at a time, waggling her fingers on each side of my head to test my peripheral vision.

‘How many fingers am I holding up?’

‘Two.’ I could see them on the right side. On the left side, I couldn’t even see her hand. The weird thing was that the result was the same whether I used my left or my right eye.

Within minutes she had succeeded where I had failed, in eliminating some potential causes. Since the problem was the same in both eyes – lack of vision on the left – the cause must lurk behind the eye, in the brain. So it was either a migraine or a stroke. This was the first time the word ‘stroke’ had cropped up. It was a word I didn’t want to hear but it was what Yeats, in a quite different context, called the surprising word that is also exactly the right word. If I’d had my wits about me I might have joked, when my sight first went, that I’d had a stroke – but the reality, the ophthalmologist made quickly clear, was no laughing matter. We needed to go straight down to Emergency, she said, picking up the phone to alert them to our imminent arrival. Since I was ambulatory it would be faster if we walked rather than waited for a wheelchair.

So that’s what we did. We ambulated through the hospital as we had previously walked to the café, with me clinging to my wife’s arm. The difference, because of the drops, was that as well as acting like an ageing teenager on E, I now looked like one as well: my pupils were the size of dinner plates.

A nurse showed us into a curtained cubicle. I changed into one of those hospital gowns that tie at the back, the purpose of which seems to be to enfeeble you, to reduce your capacity for independent action. To walk even a few steps is to risk the ignominy of exposing your bottom to the world. You are now a patient, the gown decrees, the recipient of treatment, someone to and for whom things are done. An ER doctor saw me straightaway. He touched my legs and face on both sides, asked if I could feel what he was doing: I could. I could also grip hard with either hand and extend both arms and legs. I could swallow and speak perfectly. After each of these little tests the doctor said: ‘Good.’ It wasn’t just reassuring to hear this; there was also the pride you felt at school, that you still feel in the course of a tennis lesson, when you get the answer right or execute a stroke correctly: the clever-kid-in-class glow, the sense of achievement and pride that you are not such a klutz, not a complete physical and mental wreck like that guy moaning over there, all whacked-out and smashed up on a gurney. Less encouragingly, I had been downgraded from my previous ambulatory status: I was now wheeled along on my own gurney to the MRI scanner, which was in a different building. With my pupils enormously dilated the Californian light was so strong I had to keep my eyes screwed shut.

There was only a short wait before I was fed into the scanner. The procedure was very similar – but quite different – to something I’d experienced a few days earlier in the Perceptual Cell in James Turrell’s retrospective at the Los Angeles County Museum. The highlight of that exhibition was to be slid into something that looked like an MRI machine by two assistants in white lab coats. Once inside you were bathed in soft blue light. There were two settings and I had, naturally, opted for the stronger. The light began to pulse and change. Headphones played beatless music that encouraged complete surrender to a non-corporeal world of pure light. As the fractal geometries and strobes of colour gathered pace it became impossible to tell whether these glowing patterns and acid flashes were emanations of an external world or were in your head. Deep space or inner space? Either way it was like a glimpse of infinity. Infinity, not eternity. The experience only lasted ten minutes; it was possible to lose track of oneself but not of time. I would like to have spent hours in there, a whole day even.

In the same amount of time I’d spent in the Perpetual Cell, the MRI made a map of what had happened in my brain. I emerged from the clattering, unmeditative soundtrack of the scanner, clambered onto the gurney and was wheeled back to my cubicle. The doctor returned within an hour.

‘I’m afraid there has been a stroke,’ he said. ‘An ischemic stroke.’ It had occurred at the back of my brain on the right side, affecting the working of the left half of my vision. They’d need to keep me in hospital overnight for more tests. My immediate reaction – shit, I’ve had a stroke – was followed immediately by a second: thank God we have health insurance. These, in turn, were quickly followed by a third: that a series of trapdoors might be in the process of opening up beneath me. One thing leads to another, each more serious than the last. This has happened because something else isn’t working correctly, and that is wrong because something else is faulty. To find out what that next thing is it will be necessary to burrow more deeply into your being and discover how much if any of that – your continued being – you have left.

I was wheeled up into what looked, to my still dilated, NHS-habituated eyes, like a business-class hospital room. My wife went back to our apartment to get various things I’d need. In the rush to get out of the house and to the café – why hadn’t we thought ahead, why were we so obsessed with having our coffee? – I had arrived like a guest who turns up at a party empty-handed. I hadn’t brought a book because I couldn’t read. But my column for the New Republic was due the next day and I had left my laptop at home. The column involved looking closely at a news photograph and writing five hundred words about it. Thankfully, I’d already chosen the photograph so, in the interludes between tests, I began jotting down my blurry thoughts about the image on the back of an envelope. One of the intervening tests was an ultrasound of my heart and carotid artery which would, in the words of the technician running it, ‘show us where we’re at’. I could hear my heart whooshing and splooshing on the monitor. I had no idea if this was the way it was meant to sound but I had absolute confidence in my cardiovascular system.

‘Ten bucks says my heart’s in perfect shape,’ I said. But he wasn’t a betting man, the technician. Which was just as well – for him – because my heart and arteries were, as I’d boasted, pumping away like there was no tomorrow. Like there was going to be no end of tomorrows – tomorrows and tomorrows – any time soon.

‘Least now we know what it’s not,’ he said when the test was completed. We knew where we weren’t at.

In the early evening I had an intravenous CAT scan and my wife returned with my laptop. We went through an amateur series of finger-waggling tests and it seemed my vision was continuing to improve. After she left I was able to type up my New Republic notes, knock them into shape and file my copy in case I was unable to do so the next day. A good decision, it turned out, though not because of any sudden deterioration in my condition. It was such a busy night that, in the morning, I was too exhausted to think. Whenever I was about to sleep someone would come in to check my blood pressure, my pulse, my temperature, to take more blood or monitor whatever else was happening in the gates and alleys of my body. I was glad of the attention, was even pleased to see the physical therapist – it’s important to get stroke victims moving again as quickly as possible – even if his skills were, in my case, superfluous. All of this was really just build-up to the headline attraction: the neurologist who came by just before midday. He was Korean, bespectacled, a little younger than me and – I’m not sure how this came up – his daughter was at Stanford. To be in his presence, to be the beneficiary of his training and expertise, was to marvel at how thoroughly the idea of rude health had been left behind. He was a reassuring advert for the efficacy of polite well-being.

All the test results so far were negative, he said. Apart from the small matter of the stroke I was in great shape. This was as expected: I played tennis and ping-pong all the time, cycled everywhere, was as thin as a rake. I loved soy milk. My favourite meat was tofu. ‘I even take the skin off chicken!’ I told him.

We went through the familiar round of tests at which, frankly, I had come to excel: squeezing hands, face stroking, finger counting and so on. I was fine, my vision was almost entirely back, I could go home as soon as the paperwork was taken care of. The discrepancy between the seriousness of what had happened – everyone at the hospital was at pains to emphasise that any stroke is extremely serious – and the speed of my already almost complete recovery was echoed by the contrast between the extravagance and expense of the diagnostic technology and the modesty of the cure: low-dosage aspirin. Then, just as he was about to leave, in anticipation of a few test results that were not yet in, he added a prescription for cholesterol-reducing Lipitor.

By two o’clock I was back home. I had a terrible headache, but it was a very familiar form of terrible, the sort I’d had hundreds of times before, a kind of hangover from the momentous events of the previous thirty hours. I slept for a couple of hours, cycled to the beach and walked by the ocean in the late surge and swell of afternoon light.

It seemed inconceivable that I could have had a stroke. I was 55, way too young, and of all of my contemporaries I would have put myself last in line for such a thing. I’d never had a cigarette. I drank a fair bit, but less than many of my friends, and was drinking less with every year. I actively disliked all the foods you’re meant to avoid. Except doughnuts and croissants. I’d always eaten a lot of pastries and in New York my doughnut habit had got, well, not out of control exactly but I was doing one a day for four months. Twice a week I had a couple of poached eggs, but what did that count for in the face of the overwhelming healthiness of my life?

‘Well, something,’ the neurologist called to tell me the following day, ‘has sent your cholesterol though the roof.’ Instead of twenty milligrams of Lipitor I should double the dose to bring it down as quickly as possible. After speaking to him I remembered that, fifteen years ago in England, my GP had said that my cholesterol was a little high. I paid it no mind, moved to a different part of London, signed on with another doctor. As far as I could recall my cholesterol had never been tested again. Until now. Now I’d joined the great American statin-dependent democracy, was being welcomed into the community of stroke victims as featured in a clutch of nicely produced brochures.

They made depressing reading, these brochures. In a friendly way they showed people of both sexes and many races going about their fulfilling post-stroke lives. These people, regardless of their race or sex, were overwhelmingly old and white-haired and the advice – a walk is good exercise, pruning trees in the garden can be aerobically helpful – applied to a demographic to which I did not belong. Even as I rejected the proffered kinship, however, I remembered something that had happened nine months previously. I’d been sitting in a café when my left thumb and forefinger went completely numb. It had been freezing outside, but, looking back, this numbness had nothing to do with the temperature: it was absolute. Not just numb or cold, more like dead. It only lasted a couple of minutes. On a couple of other occasions my vision had gone sort of sparkly and bleached-out, but these episodes were so transient that I forgot about them too. Such things, I read now, were called transient ischemic attacks: so fleeting they were difficult even to register until something more extreme occurred to give them definition and meaning. Until then they had nothing in common with anything you might think of as stroke-related.

Back in London I often used to bump into the writer Gilbert Adair on Portobello Road, both before his stroke (always smoking, never healthy-looking) and after, when he was, as he put it, ‘sadly diminished’. I last saw him, shuffling around with a friend, struggling to remember who I was, a couple of months before he died in December 2011, aged 66. Gilbert was stroke-brochure material who had led a perfect stroke-conducive life. I may have been unlucky to have had a stroke at all but it was a stroke of luck that I’d had such a mild one. Within 48 hours there was almost no physical difference between the way I’d felt before and afterwards. I was able to play ping-pong on Friday and Saturday (a very good workout for the eyes; one that persuaded me there was still some slight vision loss between 10 p.m. and midnight in the clock-dial scheme of things). On Monday I was playing tennis again. Apart from being at increased risk of another stroke I was fine, but psychologically I was conscious that the ground could open Adairishly beneath my feet at any moment. Every time I got out of the bath I worried that the giddy rush of blood from – or is it to? – the head might be the bow-wave of an approaching stroke. I was scared of bending down – and I was worried, constantly, about my brain.

There had certainly been some cognitive impairment, but my wife insisted that this had occurred before the stroke. I used to pride myself on my sense of direction but that had long gone south, or maybe north or east. I had trouble concentrating but that too had been going on for ages; I put it down to the internet, not to my brain blowing a fuse or springing a leak. So no, nothing had gone permanently wrong in my head, or at least nothing had gone wrong that had not been in the process of going wrong for a while, but I now regarded my head and the brain snuggled warmly inside it in a new and vulnerable way. I’d been looking forward to signing up for a medical marijuana card in LA, but the prospect of smoking pot now seemed quite dreadful. While marijuana might meliorate the symptoms of some conditions it seemed guaranteed to send the stroke victim spinning into an epic bummer in which you either fixated on the stroke you’d just had or the one that could blow your brain apart at any moment, the one that might be brought on by worrying about it. That was the thing about all this: it was a brain thing, and I loved my brain and the way it had been going about its business so gamely for more than half a century. Let’s say you have something wrong with your liver or heart. Terrible news. But if you’re lucky, if you get another one and take the right medication you’ll be back to your old self again. But with the brain, the one you were born with either works or it goes wrong and you start sliding away from yourself. Even if a better, cleverer brain – a brainier brain – had been available for transplant I wouldn’t have traded in the addled one I had. And although the problem, we’d quickly discovered, wasn’t in my eyes, that’s where it had manifested itself, and I loved my eyes too, especially here in southern California where half the reason for living, possibly all of it, was to see and be seen. I loved seeing the ocean and the sunlight and the gorgeous, tanned, fat-free, screen-tested bodies as they muscled and jogged along the beach, adorned with zero-cholesterol tattoos of Maori designs and lines from Infinite Jest.

A week after the stroke we bought a car. It had belonged to a friend who had recently died. Almost exactly a year ago we’d had dinner with her husband while he was in London. When he got back to LA his wife (who, until a few weeks previously, when she’d started to feel tired all the time, was much fitter and more energetic than him) was diagnosed with cancer. We saw them both when we visited in May; she seemed to be doing well with chemo – and then, in October, she died. Another friend, in London, died last spring after years of cancer treatment, remission and recurrence. They were both in their forties. My parents, by contrast, had lived very long lives. My dad soldiered on till his ninetieth birthday – to the day – in spite of a diet dedicated solely to increasing the chances of a stroke, cancer or heart attack. It’s a shame that he wasn’t around to enjoy the irony and comedy of his son having a stroke at 55.

So that’s where we are, where we’re at. Life continues unchanged except that I’ve had to cut out the twice-baked hazelnut croissants and I’m not playing tennis just now: I pulled a calf muscle which is taking ages to heal. A side-effect of Lipitor or a main-effect of middle age? I don’t know, but in keeping with the advice in the brochure I’m still getting plenty of exercise. I’m constantly out on my bike, in the amazing light and weather. How long would you need to live here to start taking that for granted? Longer, if you’re from England, than one lifetime, even one as lengthy as my dad’s. There’s a line in Tarkovsky’s Solaris: we never know when we’re going to die and because of that we are, at any given moment, immortal. So at this moment it feels pretty good, being where I’ve always longed to be, perched on the farthest edge of the western world. There’s a wild sunset brewing up over the Pacific. The water is glowing turquoise, the sky is turning crazy pink, the lights of the Santa Monica Ferris wheel are starting to pulse and spin in the twilight. Life is so interesting I’d like to stick around for ever, just to see what happens, how it all turns out.