Comparison of two ophthalmoscopes for direct ophthalmoscopy.

Background: To measure the ease of use and performance of the Optyse lens-free ophthalmoscope compared with the standard Keeler pocket ophthalmoscope, and to assess its suitability as an inexpensive ophthalmoscope for medical students.

Design: Randomized cross-over study.

Participants: Twenty second-year medical students, 10 as ophthalmoscopists ('observers') and 10 as 'patients'.