Open versus closed view autorefraction in young adults.

PURPOSE: While there are numerous studies comparing open-view autorefractors to subjective refraction or other open-view autorefractors, most studies between closed and open-view autorefraction tend to focus on children rather than young adults. The aim of this study was to determine the concordance in non-cycloplegic refractive error between two modern objective autorefractors: the closed-view monocular Topcon TRK-2P and the binocular open-view Grand Seiko WR-5500.

METHODS

Fifty young adults aged 20-29 years (mean age 22 ± 1.6 years) underwent non-cycloplegic autorefraction using the Grand Seiko WAM-5500 (open view) and Topcon TRK-2P (closed-view) autorefractors on both eyes. Findings were expressed as the isolated spherical component and were also converted from clinical to vector notation: Mean Spherical Error (MSE) and the astigmatic components J0 and J45.

RESULTS

Mean MSE ± SD was -1.00 ± 2.40D for the Grand Seiko WAM-5500 compared to -1.23 ± 2.29D for the Topcon TRK-2P. Up to seventy-six percent of the cohort had mean spherical errors from the Topcon TRK-2P which fell within ±0.50D of the Grand Seiko reading and 58% fell within ±0.25D. Mean differences between the two instruments were statistically significant for all components (J0, spherical, and MSE) (p < 0.01), except J45 (p > 0.05).

CONCLUSIONS

The differences in non-cycloplegic MSE between these two instruments are small, but statistically significant. From a clinical perspective the Topcon TRK-2P may serve as a useful starting point for subjective refraction, but additional work is needed to help further minimise differences between the instruments.