thinking outside the tank

Happy birthday dear central retinal vein occlusion

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This blog entry celebrates the second birthday of my central retinal vein occlusion. It shows the diary entries I made two years ago including diagrams to record what was happening to my vision. Although it was scary at the time, I’ve learned to live with it and in fact I feel as though I’ve had a lucky escape. There are forms of occlusion that get worse rather than better, as mine did, and there can be complications like the growth of new veins that interfere with sight.

If ontology recapitulates phylogeny then the human eye was previously: a sprite, a praying mantis, cotton wool, a monocle, a tropical fish, a dag, and a bushy eyebrow. These are all the phases through which my eye passed.

Monday, 19Feb07 – An Ocular Event


“0640 – ocular event. 0810 – Westway. Dr. Hulme suggested go to St.Paul’s. 0930 – St.Paul’s. First noticed ‘droplet’ that moved as I looked right-left. BP 164/90 Central Retinal Vein Occlusion”

At 0640 on the morning of 19Feb07 I was sitting quietly with a cup of tea watching the BBC News. I felt relaxed and still had 10 minutes before I needed to set out for work. For the previous two weeks I had suffered from a heavy cold but on that morning I felt well.

Quite unexpectedly, two things happened to my right eye; a halo of light appeared around its periphery and shortly afterwards, at the centre, I could see a pattern of white lines. I had recently started to learn Kanji – one of the sets of characters used in Japanese – and for all the world this pattern looked like a couple of Kanji characters. The halo lasted for 5 minutes but the central pattern persisted. I’m not normally one to panic and as an IT Consultant on contract who only gets paid when he turns up for work, I set off. The 15-minute journey was uneventful and I settled at my desk, computer on. It didn’t take long to realise there was something seriously wrong which needed investigation. The Kanji characters were still visible and, looking at the computer screen, all vertical lines were chopped into sections offset horizontally from each other. I logged off and went home.

By 0810 I was in my local medical centre to get an emergency appointment that day. Fortunately, one of the doctors was in the reception area as I explained my symptoms and recognised my description. She suggested that we go (my wife was driving by this time) straight to the St.Paul’s Clinic at the Royal Liverpool University Hospital.

By 0930 I was waiting to be seen by an ophthalmologist, but first there was the standard eyesight test and a dose of drops to dilate the pupils. At this time I first noticed what looked like a dark droplet that flicked rapidly from right to left and back as I moved my eyes.

By half-ten the diagnosis was in; I had a Central Retinal Vein Occlusion. In medical terminology, an occlusion is the closure of a blood vessel, and in this case it was one of the veins located at the centre of the eye that carries blood away from the retina. Either there was a blockage of the vessel or my blood pressure was excessively high; the result was a leakage of blood into the vitreous humour and a disturbance to the neat layers of the retina.

To investigate the cause of the occlusion a series of blood and urine tests was planned. These would look for diabetes and high cholesterol and a range of other possibilities. It was suggested I take 75mg of aspirin daily, if my stomach could take it, to reduce the risk of clotting. They measured my blood pressure and found it was 164/90 a disturbingly high figure.

At this stage I didn’t realise how much my life would have to change. I was still in shock from what had happened and was wondering if this would be a permanent problem. The internet, of course, provided me with all sorts of scary prognoses and I concluded that the best approach would be to go to bed and relax. If stress had given me high blood pressure then worrying about this new problem would not help.

Tuesday, 20Feb07 – Praying Mantis and cotton-wool


“good sleep, much improved vision. The Kanji have almost gone, and I’m left with the sprite darting about. “

“0645, sprite grows a tail. I get the feeling it’s some kind of clot and it’s breaking up. I’m hopeful it will dissolve and disappear.

“1240 – feels very tenuously attached. ‘cotton wool’ effect. Increased sensitivity to light through the day.”

Driving to work, the small, dark droplet which I called the ‘sprite’ developed a tail which also flicked about as I looked first one way and then the other. I had to force myself to concentrate on the road. Over the course of the morning, my feelings went from hope that the appearance of the tail meant the sprite would break up and disappear, to frustration at the way it developed.

You can see in the diagrams I drew how the tail stretched out and became forked, and then how the material from the sprite was spreading out. By noon the sprite had transformed into a praying mantis with antennae and feelers that swayed from side to side. Forty minutes later it felt as though one good flick of my head would somehow release the insect, allowing it to pursue an independent life. More of the material from the droplet, which I was beginning to realise was blood, was spreading out beneath the body of the mantis to give an effect like cotton-wool.

Frustration became distress as I recognised the possibility I might be spending the rest of my life with this mess inside my eyeball. Once again, the internet provided a range of drastic options, including the vitrectomy – a procedure in which the vitreous humour is removed. The fact that I would have considered that operation tells you a lot about how I felt. When you are used to excellent eyesight it verges on intolerable to have anything wrong at all.

Wednesday, 21Feb07 – The Tropical Fish


“floater is less obtrusive this morning, will it dissolve, I wonder ? “

“tropical fish”

“0730 Royal Liverpool – blood tests.”

“ask about vitrectomy – removal of vitreous humour.”

The first thing to do today, even before eating, was to go to the Royal Liverpool Hospital to leave some blood. At half-seven in the morning there was no queue and I was seated with my sleeve rolled up straightaway. I thought it was strange that the nurse who stabbed the needle into my arm wasn’t wearing gloves; surely in these days of HIV infection she should have protected herself, and me, from that risk. It turned out later that this blood sample was misplaced and I had to go back to give more. I wonder if it’s still in a fridge somewhere or has been used to misdiagnose another patient’s symptoms.

I managed to get to work before ten, but found reading the computer screen quite difficult. The reason was, I had a big  tropical fish in my eye with its huge tail swaying gently in the current. To see the screen properly I had to flick my head to one side in the style of Stevie Wonder.

The Mandarin script on the page shows the date: 2 Moons (February), 2 tens plus 1 Sun (21st), day 3 (Wednesday)

Thursday, 22Feb07 – The Monocle



“still changing the distribution of mass, but remaining broadly the same”

“The material in my eyeball seems to be spreading. There are curious threads that look like hairs protruding from the main strands”

The reference to Pirin, which I should write as ‘Pirin, comes from The Birdcage. Robin Williams is furious at Hank Azaria for giving Nathan Lane a new drug called Pirin, but is mollified when he learns that it’s Aspirin with the first two letters scratched off. My diary entry shows this was my first day of taking a daily 75mg of aspirin which helps to prevent clotting. Some people can’t handle this because of the extra acidity in their stomachs. I don’t know yet if I’m one of them. You can get two types of aspirin, coated and uncoated. The coated tablets are easier to swallow and supposedly protect the stomach, but are more expensive. I started out with the uncoated aspirin – nothing but the cheapest for me. The trick with these is to swallow them as quickly as you can. If you wait too long they start to dissolve on your tongue and just stick there.

Inside my eye, two main strands of material developed and the blood from the original droplet was spreading out along them, and from these strands further fine ramifications grew into unaffected areas of the humour. The long strands waved about independently and I discovered towards the end of the day that, if I flicked my head to the side and then back, I could get the two strands to wrap around each other which formed a circle rather like a monocle. This had the advantage that the lower strand didn’t interfere with my reading so much and the whole mess seemed a little tidier.

The Mandarin script on the page shows the date: 2 Moons (February), 2 tens plus 2 Suns (22nd), day 4 (Thursday)

Friday, 23Feb07 – Disintegration


“material seems to flow along and build up on a filament that reaches out from the main strand”

The thin filament heading ‘south-west’ from the monocle began to swell, as the bottom part of the monocle grew more faint. It seemed that the blood was exploring new routes through the vitreous humour and once it had found a way it pushed on through.

Towards the end of the day, the “cotton-wool” returned and the whole structure started to disintegrate. Material started to spread out as the monocle was ripped apart. Some of the previous patterns reappeared – a reversion to childhood rather than ontogeny recapitulating phylogeny.

If you didn’t know it before, I guess you know now the Mandarin/Kanji for the number five. 

Monday, 26Feb07 – Total Clag


“I am now less concerned about the mess inside my eye, and more about the risk of an occlusion in my left eye. I now eat no meat, but will eat oily fish. I will have no milk or other dairy produce. I will have Pirin every day (75mg)”

“walk 25 min.”

The sketch at the top of the diary entry gives an impression of the ‘mess inside my eye’. The constant waving of my head to move the ‘clag’ to one side of my field of vision was extremely irritating, and even after managing to do that it was impossible to focus clearly.

Self-pity reached its peak as I reflected miserably on the quality of my eyesight. Times like this help you to understand how precious the senses are. I was also beginning to understand how important it would be to avoid this happening to my left eye, hence the commitment to a different diet and the plan to take more exercise. 

Tuesday, 06Mar07 – Son et Lumière


“my eye seems to have stabilised. If anything the tropical fish is less obtrusive than at first.”

“I get phenomena like a sudden flash of light if there’s a sudden noise and steady light on first retiring.”

“There’s also a sparkly feature close to centre of field of vision. Bands of light and dark moving rapidly downwards.”

“Pirin, 1 grapefruit, green tea, banana, pasta, pesto, beans, pine nuts, carrot, beetroot, walnuts”

The tropical fish and all its relatives were still living in my eye some two weeks after the occlusion. My diet was well underway and you can see that my intake was entirely vegetarian and devoid of any dairy produce at this time .

It was disconcerting to have sudden, bright flashes of light if I heard any sudden sound no matter how loud. Each flash was a reminder of the halo on the first day and a worry that something similiar might happen again. This helped me to concentrate on the diet as one of the few things I could do that might prevent a recurrence or a problem with my left eye. Previously my weaker eye, I now felt the need to preserve it as the stronger one. 

Wednesday, 07Mar07


“increased number of flashes this morning as I was waking. Maybe one every 30s for about 5 minutes.”

pirin, oats & maple syrup, green tea, banana, apple, kiwi (not good), pasta, tuna, egg, feta, savoury pancake, wine

top soil, laser printer, composting turf

The picture shows that the tropical fish has started to break up, so this day marked the beginning of the gradual elimination of material that was lurking in my vitreous humour, and I was very relieved to see the back of it. It also showed that, although the clag was still there it was much less of a problem.

The reference to top-soil and compost shows that I had decided to start my own vegetable garden. I dug up part of the lawn and created some raised beds. I needed top-soil to bring up the level.

Thursday, 15Mar07 – The Dag


“walked for 20 min. The ‘dag’ is much smaller now, as distracting as a bushy eyebrow might be – but it just let me ‘see’ better how poor is the focus in the eye – although even that seems to be improving.

Hungry – perhaps two pieces of fruit are not enough to see me through the day

pirin, oats, honey, green tea, apple, banana, mackerel, salad: carrot, celery, radish, lettuce, spring onion, beetroot

No picture today as there wasn’t much left to draw. The set of numbers at the top of the page showed that my blood pressure was 129/78, quite acceptable, and my pulse was 50 beats per minute.  My weight was 80 Kilograms and my BMI (body mass index) was 26.4. This was not so good. My target was to get my weight down to about 76 Kilos when my BMI would be 25 – or borderline overweight rather than borderline obese.


Over the following six months I made regular visits to the ophthalmologists at The Royal Liverpool Hospital. All of the blood and urine tests returned negative results and my blood pressure is normal – I think it was only high on that day because I was stressed and shocked by the occlusion itself.

I’m left wondering why this happened to me and I have an idea that might be worth somebody pursuing: in the two weeks before the occlusion I had suffered from quite a bad cold. To help relieve this I used a nasal decongestant spray. It’s possible, given how difficult it is to deliver the correct dose, that I took an overdose of the active chemical. I read later that this acts as a vaso-constrictor, in other words it narrows the blood vessels. Could this, perhaps, have built up the blood pressure in the fine vessels that feed and drain the eye to the point where blood haemorrhaged into my eye?

Copyright © Colin Hazlehurst 2009


Written by netkingcol

February 16, 2009 at 12:05 pm

Posted in diary, health, medicine, personal log

Tagged with , , , , ,

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