title: Comparison of two ophthalmoscopes for direct ophthalmoscopy.
abstract: 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.
  
  
  METHODS
  Randomized cross-over study.
  
  
  METHODS
  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.
  
  
  METHODS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: College of Medical and Dental Sciences, University of Birmingham, UK.
authors.forename: Niraj
authors.initials: N
authors.lastname: Mandal
authors.forename: Philip
authors.initials: P
authors.lastname: Harborne
authors.forename: Sarah
authors.initials: S
authors.lastname: Bradley
authors.forename: Nikki
authors.initials: N
authors.lastname: Salmon
authors.forename: Roger
authors.initials: R
authors.lastname: Holder
authors.forename: Alastair K
authors.initials: AK
authors.lastname: Denniston
authors.forename: Philip I
authors.initials: PI
authors.lastname: Murray
mesh_terms: D018592:Cross-Over Studies; D004504:Education, Medical, Undergraduate / Q000379:methods; D004867:Equipment Design; D006801:Humans; D009885:Ophthalmology / Q000193:education*; D019721:Ophthalmoscopes; D009887:Ophthalmoscopy / Q000379:methods*; D009898:Optic Disk / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D013337:Students, Medical; D013663:Teaching / Q000379:methods*