They do say that you don't realise what you've got until it's gone. And for all its faults, I'll never moan about our computer system again. Well, not for the rest of this week, anyway. We had a major server crash at work overnight, resulting in the temporary loss of three of the hospital's computer systems. Two were restored within the hour, but the third was out of action for the rest of the day. And that system was ours. Every bit of software used by the Diabetic Retinopathy Screening Programme was unavailable until late afternoon.

No appointments could be booked or rearranged, no grading could be done, and out in the field, I had to get through a clinic using Photoshop and a few sheets of paper. Capturing the images was frustratingly time-consuming, but what I missed most were the little things: the ability to check past results, to see a patient's eye history, and even just the computer's ability to tell me how long a patient had been waiting since I administered the eye drops. I had to take addresses, GP details and medical records by hand, and ended up with pages of scrawled notes that only a doctor with a graphology degree could read.

I had patients asking me if their retinopathy was any worse than last year, or if their vision had changed, and I simply couldn't tell them. I didn't have access to their previous results, let alone past images or treatment records. Conversely, I had a lady who could barely see the top line of the eye chart, yet claimed her vision had not deteriorated in any way. I had no way of checking if this was true, and was unable to challenge anything she said. A lot of my working life is spent in low-level lighting, but today I was completely in the dark. And I didn't like it.

Our computer system may not be perfect, but when you're suddenly forced to work without it, you realise just how much we take the thing for granted. We have a wealth of information at our fingertips - in fact we know more about the patients than most of them do - and when that information's not accessible, you realise what diabetic blindness is all about. It's obvious that we couldn't do retinal screening without state of the art camera equipment, but in many ways our computer system is just as priceless. The thought of having all that information printed on cards and sitting in filing cabinets sends a shiver down my spine. We might moan about IT issues and technical breakdowns, but we should be damn grateful that we live in an age of computers and digital photography. The alternative doesn't bear thinking about.