Abstract
Purpose. To assess the performance of the 2Win eccentric videorefractor in relation to subjective refraction and table-mounted autorefraction.
Methods. Eighty-six eyes of 86 adults (46 male and 40 female subjects) aged between 20 and 25 years were examined. Subjective refraction and autorefraction using the table-mounted Topcon KR8800 and the handheld 2Win videorefractor were carried out in a randomized fashion by three different masked examiners. Measurements were repeated about 1 week after to assess instrument reproducibility, and the intertest variability was compared between techniques. Agreement of the 2Win videorefractor with subjective refraction and autorefraction was assessed for sphere and for cylindrical vectors at 0 degrees (J(0)) and 45 degrees (J(45)).
Results. Reproducibility coefficients for sphere values measured by subjective refraction, Topcon KR8800, and 2Win (+/- 0.42, +/- 0.70, and +/- 1.18, respectively) were better than their corresponding J(0) (+/- 1.0, +/- 0.85, and +/- 1.66) and J(45) (+/- 1.01, +/- 0.87, and +/- 1.31) vector components. The Topcon KR8800 showed the most reproducible values for mean spherical equivalent refraction and the J(0) and J(45) vector components, whereas reproducibility of spherical component was best for subjective refraction. The 2Win videorefractor measurements were the least reproducible for all measures. All refractive components measured by the 2Win videorefractor did not differ significantly from those of subjective refraction, in both sessions (p > 0.05). The Topcon KR8800 autorefractometer and the 2Win videorefractor measured significantly more positive spheres and mean spherical equivalent refraction (p < 0.0001), but the J(0) and J(45) vector components were similar (p > 0.05), in both sessions.
Conclusions. The 2Win videorefractor compares well, on average, with subjective refraction. The reproducibility values for the 2Win videorefractor were considerably worse than either subjective refraction or autorefraction. The wide limits of reproducibility of the 2Win videorefractor probably limit its usefulness as a primary screening device.