The use of computer-aided learning (CAL) in medical education has grown considerably in recent years. CAL has a number of attractive educational features, and computer simulations have been shown to improve learning in health professions education. This paper describes the formative evaluation of a multimedia CAL simulation used in a third year ophthalmology clerkship. The CAL program combines the use of a Macintosh computer with a mannequin head, housing two motor driven camera diaphragms which simulate pupil response. This allows students to practice the“swinging flashlight test”, an important clinical exam commonly used to detect visual dysfunction. Five questions are addressed in this study and the formative evaluation process is described. The highly positive results are then presented, with suggestions given for improvement followed by implications for future development.