Ophthalmic Assistant

Answer: C - 3 to 4 mm.

In dim illumination, the average pupil diameter is 3 to 4 mm. This can be measured by shining a light from below the patient’s nose so that the pupils are just visible to the examiner; the lightis not shone directly into the patient’s eye. The assistant can then use a millimeter rule to measure the pupil diameters. With experience, theassistant will become fairly accurate at estimating this measurement at a glance.