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The big problem is patients. They have a nasty habit of being human, so they fidget, they blink, their eyes water and they flinch and, generally, are not terribly keen on having bright lights pointed at them, especially by students.
With regard to the students, they are the other potential problem. They fiddle about and refocus and change the illumination and refocus and lose the fundus and refocus, while the patient is fidgeting and blinking. It's not an ideal situation.
Then there's the issue of safety. Modern slit lamps can damage maculae. At a high setting you can harm a macular if you linger more than eight seconds, and even at a medium illumination level you are only safe for about 13 seconds. Given that the observers are inexperienced, the tutor has to watch them rather carefully. Most tutors only have one pair of eyes which they usually point in only one direction at a time, so you can't have many students practising at any one time, and unsupervised practice isn't really an option.
For the registered practitioner, it would be nice to be able to practise your moves when there isn't a real patient the other side of the slit lamp to embarrass you.
New alternative
It was, therefore, a happy day when my colleague Richard Llewellyn gave me the name of Andy Levy, Professor of Endocrinology at the University of Bristol.
In his spare time, Levy makes medical mannequins, including model eyes that were developed to train and assess doctors in ophthalmoscopy. Each eye is constructed from a table tennis ball painted on the inside with orange paint and with a cut-out of the optic disc and major blood vessels positioned via a 10mm hole in the front (Figure 1).
The lens and diaphragm assembly of a single use camera is mounted in the hole. The whole eye can be mounted on a stand by pushing it into another cut down table tennis ball acting as a socket. The stands originally supplied were developed for ophthalmoscopy, so I mounted the eyes into polystyrene display heads which could then be strapped into the slit lamp using bungee cords (Figure 2). This gave a brow for the practitioner to rest his fingers on.
The clever part is that a series of words appears at various points of the fundus. If the viewing lens is correctly focused, the word can be read. Moving from word to word is a good way to learn navigation around the fundus and for the more peripheral words it is necessary to tilt the viewing lens appropriately to read the whole word. If you can read all of the words, you have the basic skills of slit-lamp BIO. The basic eye costs £25 and the heads about £5, so even if you factor in the Blue Peter session joining the two together it's hardly a major investment. There is also an eye available with additional targets (£50) so that you can practise viewing the periphery. The money goes to the university, so you can feel a bit smug about sponsoring education as well.
As a teaching and practice aid the eyes are extremely useful, allowing students to practise at their own pace and removing the need to worry about (or indeed, pay) patients. Myself and colleague Bill Harvey have used these eyes a number of times and for the basic acquisition of skills they allow far quicker progress than the use of live patients.
They may also have wider application. They have been used in professional examinations for doctors. The eyes offer a standardised task. Using live patients, there is no guarantee that they will turn up on the day with the right type of fundus anomaly of the right degree of difficulty. The candidate's observations are easy to mark, since the words are either seen or not.
Given that there are also health and safety concerns regarding live patients used for repeated slit-lamp BIO examinations, these eyes, or something similar, might be a good way of assessing entry-level BIO skills in our own professional examinations.