Clinical evaluation of the Topcon BV-1000 automated subjective refraction system

The BV-1000 is a new instrument that performs binocular autorefraction and subjective refraction. The aim of the study was to evaluate the accuracy of the BV-1000 compared with subjective refraction without cycloplegia and the repeatability of the BV-1000 in subjects without cycloplegia.

BV-1000 binocular autorefraction (mean of three measures) and automated subjective refraction was performed on 100 eyes and compared with practitioner subjective refraction. After BV-1000 assessment, the result was modified by the investigator in the form of a binocular addition; the practitioner was masked as to the result of the BV-1000. Repeatability was evaluated by comparing the test-retest data on 40 eyes. Refraction data were converted into Fourier component terms: mean spherical equivalent (MSE), J0, J45, and vector dioptric difference (VDD).

Mean difference of MSE (BV-1000 subjective vs. practitioner) was 0.05 +/- 0.35 D (p = 0.13), whereas after binocular addition, the mean difference in MSE was -0.01 +/- 0.21 D (p = 0.67). The mean difference of MSE (BV-1000 objective vs. practitioner) was +0.10 +/- 0.37 D (p < 0.05). Mean difference in J0 and J45 was -0.03 +/- 0.12 D (p = 0.09) and -0.02 +/- 0.10 D (p = 0.06), respectively. More than 95% of cylinder powers were within +/- 0.50 D. The median VDD was 0.35 D (range, 1.38 D; interquartile range, 0.31) for comparisons of BV-1000 subjective refraction and the practitioner. A median VDD of 0.25 D (range, 1.06 D; interquartile range, 0.16) was found after binocular addition correction. There was no statistically significant difference (p = 0.73) in spherical intereye difference between BV-1000 subjective and subjective refraction. Mean spherical intereye difference (spherical balancing error) between the BV-1000 and practitioner subjective refraction was -0.02 +/- 0.24 D. Repeatability as described by the mean difference between occasions for MSE was found to be -0.06 +/- 0.19 D, -0.02 +/- 0.08 D for J0, and -0.03 +/- 0.07 D for J45.

The subjective refraction routine within the BV-1000 improves the results of simultaneous binocular autorefraction data. The BV-1000 provides an accurate and repeatable measure of subjective refraction after binocular addition.