As a general rule, I like screening teenagers. They usually don't need eye drops, their vision is good, and they can follow every word you say without a hearing aid. In my experience, they tend to be well brought up too, because the ones with bad parents don't bother turning up to retinal screening appointments.

Of course there are bound to be exceptions, and I met one today. I don't know if St Trinians have opened a branch nearby, but the 15-year-old girl I screened this morning was straight out of the films. Bizarrely, her mother was lovely, and just how a parent should be: polite, respectful, interested in her daughter's health and concerned about the results. I can only assume the girl takes after her father.

Things started badly when I attempted to do the VA, and the girl immediately started taking the mickey out of me to my face. To my astonishment, she informed me that I have a "stupid posh voice", and that I sound funny. I was tempted to say "see how funny you find these eye drops", but sadly she didn't need any. So I went straight for the photos, with her throwing a strop between each one, and refusing to remain seated at the camera.

Her mother did her best, but the girl was in no mood to take any notice. So when it came to pointing out the problems with the girl's retinas, I addressed the information to the mother. Like a toddler trying to get her parents' attention, she then tried to break the external light off the camera. When that failed, she wiped her fingers on the lens. Naturally I moved the whole thing away from her. So she grabbed my mouse and started clicking randomly on the screen.

Now, learning difficulties and behavioural problems I can understand, but this girl was fully aware what she was doing, and simply didn't care. Her helpless mother even told me that she'll be going off to college next year, and university two years later, and that she's terrified she'll stop taking her insulin. She has good reason to be worried: apparently her daughter was hospitalised last year after refusing to take it while away from home.

We have a section on our patients' notes where we can add a warning for next year's screener, in case of a difficult patient. The moment she'd left the room, I opened it up and started typing. And then I stopped and deleted it. I wouldn't want anyone judging me on the person I was when I was fifteen, so I decided to give her the benefit of the doubt. There's a world of difference between fifteen and sixteen, and with a bit of luck she'll be a changed person in twelve month's time. Here's hoping, anyway.