Ten years ago, visual impairment was just an abstract but certain concept. Now it's a daily reality. "What can you see?" people like to ask me. Go to the bathroom, find a toilet-roll tube, cut it in half lengthways, stare down the inside and you've got something not dissimilar. The middle is there, but the sides, top and bottom aren't any more. It's a bit like looking at the world through a couple of peepholes.
Retinitis pigmentosa is the blanket name given to a heterogeneous group of inherited and incurable disorders of the retina which affect around one in every 3,500 people. I'm one of them. The condition causes the photoreceptive cells on the retina slowly to die off, resulting, in my case, in the loss of peripheral vision (the bit you use to move around or spot someone waving out of the corner of your eye) and the development of tunnel vision. My central vision (the area used for seeing detail - reading and writing, for example) remains intact, apart from a slight distortion you can liken to looking through a dirty windscreen. This blurring is caused by macular oedema (a swelling, or water retention, on the retina), a common side-effect of the primary disease. In time, these peepholes will shrink to pinholes and I'll go blind.
So this is how it is. It's not a fair or enviable state of affairs, just a different way of being. But now imagine I am somehow bringing this tunnelled view of the world upon myself, that there's a degree of psychological control or choice involved. For many months, I wrote in Guardian Weekend about playing the field, going blind and a tattooed man who stole my unsuspecting heart. I openly admitted my fate, and hung out the rotten laundry of my life for folk to feast upon. From time to time, people would write to tell me they liked it, hated it, knew someone at sea in the same boat or, in the case of one letter from a concerned reader in Scotland, that this blindness game is just a case of mind over matter.
"Dear Rebecca," the letter read, "I worry that you have accepted a self-fulfilling prophecy. Please consider contacting Charlotte Gerson at gerson.org. My father was an eye surgeon and knew that retinas could regenerate. Do not give up on God's good work."
The notion of the self-fulfilling prophecy in relation to disability is a common one (he who can't hear just needs to listen harder; she who puts her mind to it will walk again). Disability is still largely regarded as something that must be triumphed over with medical intervention, single-mindedness and sheer determination. It remains the responsibility of the individual (rather than the collective responsibility of society) to overcome, normalise and fit into the unaltered world around them as best they can. To overcome the subhumanism with which many people regard physical impairment, the disabled person must also become superhuman in their attempt to put it right again.
The upshot of this onus on triumph, correction and normalisation is a rejection of difference. Just to be different, or disabled, becomes something to be abhorred and avoided, a metaphor for shame and failure that sees people going to extraordinary lengths to hide or correct their impairment. This societal emphasis on the correction or curing of difference leaves every impaired person under pressure to do all that they can to be as near as possible to the model of normality because it's just not OK to be otherwise. If you don't subscribe to the pursuit of normality and instead give yourself an easier ride by ditching painful operations, cover-ups and quackery in favour of accepting that your body is just fallible, you end up rendering yourself open to a charge of not trying hard enough and of potentially fulfilling your own prophecy.
In the early years after my diagnosis, I wanted nothing to do with blindness. I was repulsed and terrified by the idea of being different and remained incredulous of the fact that there was, according to my doctors, nothing that could be done. In my denial and fear, I became obsessed with looking for something to make me "normal" again. These were days long before you could browse the internet and, with no Google to search, all I could do was repeatedly ask my ophthalmologist if he knew of, or thought there would ever be, a cure or treatment. I just wanted him to say, "Yes," but he never did. Instead, he gave the same unambiguous response that, while research was progressing, I must plan and live my life with the certainty that blindness was inevitable.
I scoured newspapers and journals - he must be wrong. The Observer columnist Sue Arnold (who herself has RP and is registered blind) ran a piece saying smoking Jamaican skunk had temporarily improved her vision. I hung on her every word and obliterated myself to no avail. A woman I met in India said perhaps I should pray a little harder (I'd never prayed at all). And a friend in America said, "Try vitamin A, it's good for vision" - I did, and nothing happened. I went to a support group and sat in a circle with a bunch of people whose solidarity existed not in their shared experience of losing sight, but in their shared aim to find a fixative, get the hell out of that group and re-enter the majority world - it was all they could talk about.
Then the internet arrived and suddenly I had access to all the quackery the world had to offer. (Take a quick trip to Google today with the words "blind" and "cure", and up will spring, among others, Lorraine Day, MD, of California, an evangelical Christian and self-styled miracle-maker, whose self-help CD, Eye See, claims to prevent and reverse eye disease, and the Sanoviv Medical Institute, a holistic hospital on the Baja coast of Mexico, which claims to have answers to my vision loss and charges $4,000 for a four-day assessment.) But by this point I had long accepted my consultant's word and resigned myself to the fact that there were no secret cures, only unproven promises predicated on a desire for normality that had people chucking cash and hope at anything. So I kept my money in my pocket, accepted my vision loss and gave the matter little more thought - until that letter from Scotland arrived and I found myself climbing back into the self-healing saddle, only this time for a very different reason. The accusation of the self-fulfilling prophecy had irked me, as if anyone would say yes to being sucked into the darkness of their own skull if there were a degree of choice involved. I had a point to prove. "I'll do this Gerson thing," I said to myself. "It won't work and then they'll eat their hats."
The Gerson Therapy is an intensive nutritional and detoxification treatment that allegedly sends cancer cells scampering off into remission and prevents and corrects "most of the 1,500 degenerative diseases", including (so they say) the one I get to call my own. The therapy works on the principle that if you flood your body's cells with nutrients, enzymes and minerals from a vast quantity of fresh organic produce, then the body's natural immune defences will be strengthened to a level at which it will be capable of curing itself. This process of "hypernutrition" is said to bring about the release of excess sodium and toxins within the body, which are then removed with the help of coffee enemas to stimulate the activity of bile ducts, liver and bowels.
Devised in the 1940s by the German-born physician Max Gerson, while he was looking to cure his own headaches, the therapy is now promoted through numerous books and videos by the San Diego-based Gerson Institute. The daddy of these publications comes courtesy of Charlotte Gerson, Max's 82-year-old daughter. The Gerson Therapy - The Amazing Nutritional Program For Cancer And Other Illnesses is a mix of ill-organised, repetitious jargon propped up with anecdotal case histories citing miraculous tales of folk who have apparently risen from the near-dead or shrugged off an illness that's been bothering them for years.
So how, exactly, does it work? It goes like this: drink 10 (13 if you are treating cancer) glasses of freshly squeezed organic carrot, apple and green vegetable juice a day, stick to a vegan diet void of dairy, sugar, fats and salts, down a cocktail of supplements and two tablespoons of flaxseed oil a day, inject the fat of your buttocks with crude liver extract daily and take two to five self-administered coffee enemas a day to eliminate toxic residue and diseased tissue.
But does it really work? While the Gerson Therapy has many public proponents, it has since its inception been subject to much criticism. Several favourable accounts have been written by individuals claiming it cured their terminal cancers, and in 2004 Prince Charles gave it an enthusiastic endorsement and called for more research into the area. However, there remains no substantive evidence to support the view that the therapy is the effective treatment for cancer and the other 1,500 degenerative conditions that it claims to be; there have been no independent controlled clinical trials or comprehensive research undertaken. In relation to its treatment of eye problems, there is no evidence to suggest any research has ever been carried out.
So, with no proven scientific basis, scepticism prevails among medical professionals, many of whom argue that coffee enemas can cause potentially life-threatening infections and severe dehydration. The charity Cancer Research UK echoes these concerns, warning of the potential dangers of enemas and advising caution when considering unproven and expensive "potential cures", such as the Gerson Therapy, to which patients and their families who "will try anything if they think it might work" can be especially vulnerable.
The Gerson Institute itself remains vague about statistics and patient success rates, instead relying on anecdote as evidence of effective treatment. Prospective patients are provided with a testimonial list of 150 people who say they have found the therapy beneficial. However, with no baseline figure of the total number from which this sample is drawn, it is impossible to judge its effectiveness. And the Gerson Institute is reluctant to provide further, more specific, testimonials.
I emailed the institute to ask if it had seen patients with retinitis pigmentosa before. "Yes, we do have patients that have improved vision," replied Carol M Beard, the Institute's director of professional services.
"Do you have any testimonials on these cases?"
"I would not have the ability to find the patients' names."
So I emailed the Gerson Institute's only affiliated treatment centre, the Baja Nutri Care centre just over the border in Mexico, where the law allows types of treatments forbidden in the US.
"Can you help?" I asked.
"Charlotte Gerson has seen cases similar to yours which were helped by the therapy," replied the centre's Aleyda G Hoskins. The cost of treatment at the Baja centre is $5,500 a week: "It would be advised for you to stay at least three weeks."
I emailed Charlotte Gerson. "I am thinking of trying the therapy. Have you ever treated patients with retinitis pigmentosa?" I asked. "Can you provide me with some testimonials?"
"We have seen cases of retinitis pigmentosa vastly improved," she replied.
"Do you have any testimonials or email addresses for these people?" I repeated. "I would like to make contact with them."
"I do not have files and records, and can't put you in touch," she replied, before advising that I try the diet from home to begin with, using her book.
So for the next three weeks, that's what I did.
The Gerson Therapy sounds simple. But it's not. Not only must you do all the aforementioned things, but you must also bathe in and drink only filtered water, avoid all cosmetics and deodorants, use only organic soaps, shampoos and toothpaste, and avoid contact with newly painted rooms, new carpets and chlorinated swimming pools. You must not use aluminium cooking pots. All food must be cooked slowly over a low flame with a firm-fitting lid to preserve maximum nutrients. You must avoid smoke, tea, coffee (other than rectally, of course) and alcohol. Cut out all salts and strong flavour from your food, all oils (apart from flaxseed oil, which can be taken only cold and must not be used for cooking) and all nuts, fats, avocado, pulses, grains (with the exception of brown rice once a week and a little unsalted rye bread and porridge).
Put another way, all you can eat is fruit and vegetables. With no oil or seasoning. Everything that enters your body must be as it would be found on a tree or in a field. For the juice alone, you'll get through 20 carrots, 10 apples, three oranges, one large green pepper, two lettuces, one bag of watercress and two bunches of chard or similar greens ... a day. In other words, you can expect your monthly organic vegetable bill to come in at around £500.
Next, you can kiss goodbye to any kind of life because the 10 juices a day have to be pressed on the hour every hour, using a two-stage juicing system (costing £550) that involves first grinding the fruit and vegetables to a pulp, then loading this pulpy mixture on to a tray and jacking it up on a hydraulic press. Why? Because according to the Gerson Institute, a one-stage juicer doesn't produce the same quality of enzyme, mineral or micronutrient content as juices produced by the two-stage system. You can't have a job because you must be near your juicer at all times. You need to wash the juicer in between every go. And don't go thinking you could do anything as canny as making the juice in bulk at the beginning of the day because this is forbidden - apparently, storing the juice destroys those all-important nutrients that are going to make you well again. If you really must leave the house, then you can put some juice in a flask, but only up to four hours' worth, and wherever possible you must avoid doing this.
The whole process of chopping, grinding, pressing, washing up and drinking takes around 25 minutes. Then you have a rest for 35 minutes and just when you are getting stuck into something else, you have to start the whole merry dance again and again and again. Ten times a day, seven days a week. Week in, week out.
So my flat became full of carrots and my life became empty of everything, reduced to a perpetual cycle of giving myself coffee enema-induced diarrhoea first thing in the morning and last thing at night, juicing and washing up and juicing and washing up some more. The Gerson Therapy is allegedly a self-help treatment programme that can be administered at home, but aspects of it were too tall an order for me to follow without proper clinical supervision. Receiving injections has always given me sweaty palms, never mind injecting the flesh of my own behind, so out went the self-administered crude liver oil injections and the cocktail of supplements. I omitted the purified bath water, too, because there was just not enough room in my small flat for a filter that big.
The rest, however, I stuck to religiously. Not a single forbidden morsel passed my lips. My life became Gerson. Friends called and asked what I'd been up to. "Juicing," I'd reply. The tattooed man rang to see if I wanted an introductory meeting with his mum. "I can't," I said, "I'm juicing." Someone sent me a text message asking if I wanted to see their band play that night. "I can't come. I'm juicing," went the message back. People popped round to see me. My hospitality was reduced to offering a dry potato and carrot juice before interrupting any conversation with the cry that I just needed quickly to make some juice. The Gerson Institute says you should start to see results in three weeks, but for optimum results you must stick to the programme exactly, no wavering, no cheating, no life, for one to two years.
Day 1 I've got a splitting headache and feel anxious at the prospect of not eating anything but vegetables for the next three weeks. Day 3 I feel dizzy and start to worry that maybe I'm doing myself more harm than good. By day six, I've lost 4lb - I'm pleased because in the weeks running up to this experiment I ate everything in sight, and the night before it started I consumed a whole tub of Ben & Jerry's in solitude. Day 7 My step-sister comes round and says my skin looks great. Day 8 My body has gone into shock with the total lack of fats and protein, and I've gained 2lb. Day 10 My mouth is ravaged with ulcers. Day 11 My other sister comes round to tell me kindly I look dehydrated, I've aged and she can see open pores on my cheeks that didn't used to be there. Day 12 I'm meant to look well and glowing with good health. I don't. I feel pale and not very interesting. My head feels like someone is slicing from the inside with a metal ruler. Day 13 A friend comes to stay and arrives with a pizza from the local supermarket. "It was on two-for-one," she says. "I'll leave the other one in the freezer for you when you've finished all this nonsense." We sit down for a meal. She's got a two-for-one spinach and ricotta pizza, I've got a dry potato with raw onion and some sliced tomatoes, and am gagging my way through a bowl of what the Gerson Therapy calls Hippocrates soup, which is, in essence, an ungratifying gruel of boiled-up veg and water; no stock, no salt, no pepper, no nothing. Day 14 I've been doing this diet for two weeks. In total, I've consumed the juice of 140 apples, 280 carrots, 42 oranges, 14 green peppers and more than 30 lettuces. Day 15 My friend has gone and I'm thinking about the pizza nestling in the freezer. A lot. Day 16 I wake up and feel great. The headaches have finally gone and I've got my energy back. Day 19 I'm watching TV. I notice that the captions appear a little clearer. I wonder if the telly people have changed the font. I tell myself I'm imagining things. Day 21 I'm counting the hours until I can eat that pizza. Day 22 I have at last finished. After three weeks of eating a diet devoid of anything but organic vegetables, I eat the greasy, processed, salt-laden pizza and promptly feel rather unwell.
The next day I visit Moorfields, the UK's leading eye hospital, to have my vision retested and to see if the Gerson Therapy has been anything other than an entirely futile exercise of solitary juicing confinement. Before I'd embarked on the programme, my peripheral vision in each eye measured between 10 and 12 degrees (normal is 160) and my central vision unaided was 6/24. To ensure I had a double baseline before my intervention, I checked back to make sure there had been no natural fluctuation in my vision in recent years. My medical records showed that both my central and peripheral vision had remained constant for the past 18 months.
So there I was, 420 carrots, 210 apples and 42 coffee enemas later, with my head, still fat with cynicism, shoved in the large dome of the peripheral-field measuring machine. "Press the button when you see the light coming," Dr Saihan instructed as pin lights entered my narrow fields at varying speeds from left, right, top and bottom.
"It won't have changed," I declared with conviction.
"You're right," he replied. "I'm afraid it hasn't. Your peripheral fields still measure 10-12 degrees. I'm not surprised; I've never heard of field gain in patients with RP."
So three weeks of perpetual juicing and grappling on the bathroom floor with a bowl of cold coffee and a giant dropper pipette had failed to change the most disabling part of my vision loss, the tunnel vision. I was still looking at the world like a butler peeping through a keyhole.
"Now let's test your central vision," Dr Saihan said. "Stand here and read from the chart ahead."
"F, N, P, R, Z, E, Z, H ... " As I read, I thought about the TV captions and sensed I was getting further down the chart than I had three weeks earlier. I carried on reading until I could go on no more.
Dr Saihan led me back into the darkened consultation room and, in his gentle and cautious manner, talked me through the results. To my astonishment, after three weeks of the Gerson Therapy my central vision had improved from 6/24 to 6/18 unaided. In real terms, this meant I could read one and a half lines further down the vision chart than I could before. What had caused this unexpected improvement? The enemas? The carrots? A miracle? A scan of my retinas taken after my Gerson experiment showed that the swelling had reduced considerably since the last scan, 18 months earlier. The improvement in my vision is likely to have occurred as a result of this reduction in retinal swelling. It is, however, difficult to ascertain whether the reduction was a direct result of the Gerson Therapy, because no retinal scan was taken the week before I underwent the three-week programme; it's arguable that the change could have occurred at any time during the past 18 months. But this would still not explain why there was a marked improvement in my central vision during the three-week intervention. It is likely it did occur as a result of following the diet.
I wrote to Charlotte Gerson to tell her of my experience. "Do you think I should carry it on?" I asked.
"We have seen some advanced retinitis pigmentosa reversed, in one case where a patient was declared 'legally blind'," she replied warmly. "You need to give it more time."
The medical professionals at Moorfields, however, remained sceptical. Dr Saihan explained that because no retinal scans were taken in the week prior to my embarking on the therapy, there was "no proof that the cystic swelling at the macula had not resolved of its own accord over the past year anyway". The UK's leading RP specialist and long-time consultant at the retinal clinic at Moorfields, Professor Alan Bird, added that it was not possible to attribute with certainty the change in my vision to the Gerson Therapy because spontaneous variations to macular oedema do occur and have been seen in the past. "From the point of view of general health, the diet sounds like a bad idea," he said, before stressing that any previous tests into treatment for macular oedema (most notably Diamox, a drug also used for treating altitude sickness) have undergone five-way crossover trials in order to be absolutely sure of the effects. My results were the outcome of one individual doing an uncontrolled experiment in their home, so in the eyes of the medical profession could not be deemed conclusive. "Interpreting results such as these is interesting but proves little," Dr Saihan told me.
Reeling with surprise that three weeks of juicing hadn't been the entirely fruitless endeavour I'd expected, I scuffed my heels home. The Gerson Therapy is no cure for blindness, it had failed to treat the primary cause of my sight loss, the RP, but I do believe (despite medical scepticism) that it quite possibly had to some extent alleviated the macular oedema and subsequently my central vision (albeit an improvement so minor I had barely noticed it myself).
So maybe the letter-writer from Scotland had been right after all. Perhaps this blindness game is just a self-fulfilling prophecy, something I can/should choose to avoid if I apply enough conviction and determination. Perhaps I should reject being different more earnestly and chase the tail of normality with more gusto. If the therapy had worked to some degree in three weeks, what if I really put my mind to it for six weeks, six months, a year, two years - and this time with the injections and filtered bath water, too?
But it's a heavy price to pay. The reality of a life on Gerson is one of housebound misery that will take away more independence than vision loss ever could, render me penniless, rob me of all social contact and limit me to an insanity-inducing existence of perpetual juicing, enemising and washing up, and all with no real proof or guarantee. And if that's the trade-off, incomprehensible as it may sound, I'd rather go blind.
· With thanks to the Organic Delivery Company (020-7739 8181, organicdelivery.co.uk).