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’. Methods:  Students used both ophthalmoscopes to examine the optic disc in each eye of 10 ‘patients’. They were randomized as to the order in which they were used. A Consultant ophthalmologist was used as the gold standard. Main Outcome Measures:  Main outcome measures were accuracy in estimating vertical cup:disc ratio (VCDR), ease of use (EOU) for each examination, and overall ease of use (OEOU). Results:  Of 400 attempted eye examinations, sufficient visualization was achieved in 220 cases to allow a VCDR estimation: 107/200 VCDR estimates with the Optyse and 113/200 with the Keeler. Accuracy of VCDR estimates was better with the Optyse by the equivalent of 0.05 VCDR (P = 0.002). There was no significant difference in EOU or OEOU between the two ophthalmoscopes. EOU for 400 examinations: median (IQR) of 6 (3–8) for Optyse versus 6 (3–8) for Keeler (P = 0.648). OEOU for 20 scores: median (IQR) of 6.5 (2–9) for Optyse versus 5.5 (3–8) for Keeler (P = 0.21). Conclusion:  Medical students found the Optyse and Keeler pocket ophthalmoscopes to be of similar ease of use and performed slightly better with the Optyse when estimating VCDR. The lens-free Optyse ophthalmoscope is a reasonable alternative to the standard Keeler pocket ophthalmoscope.