Clinical evaluation of the Shin-Nippon NVision-K 5001/Grand Seiko WR-5100K autorefractor.
OBJECTIVE
A clinical evaluation of the Shin-Nippon NVision-K 5001 (also branded as the Grand Seiko WR-5100K) autorefractor (Japan) was performed to examine validity and repeatability compared with subjective refraction and Javal-Schiotz keratometry.


METHODS
Measurements of refractive error were performed on 198 eyes of 99 subjects (aged 23.2 +/- 7.4 years) subjectively (noncycloplegic) by one masked optometrist and objectively with the NVision-K autorefractor by a second optometrist. Keratometry measurements using the NVision-K were compared with the Javal-Schiotz keratometer. Intrasession repeatability of the NVision-K was also assessed on all 99 subjects together with intersession repeatability on a separate occasion separated by 7 to 14 days.


RESULTS
Refractive error as measured by the NVision-K was found to be similar (p = 0.67) to subjective refraction (difference, 0.14 +/- 0.35 D). It was both accurate and repeatable over a wide prescription range (-8.25 to +7.25 D). Keratometry as measured by the NVision-K was found to be similar (p > 0.50) to the Javal-Schiotz technique in both the horizontal and vertical meridians (horizontal: difference, 0.02 +/- 0.09 mm; vertical: difference, 0.01 +/- 0.14 mm). There was minimal bias, and the results were repeatable (horizontal: intersession difference, 0.00 +/- 0.09 mm; vertical: intersession difference, -0.01 +/- 0.12 mm).


CONCLUSIONS
The open-view arrangement of the Shin-Nippon NVision-K 5001 facilitates the measurement of static refractive error and the accommodative response to real-world stimuli. Coupled with its accuracy, repeatability, and capability to measure corneal curvature, it is a valuable addition to objective instrumentation currently available to the optometrist and researcher.
Davies
Leon Nicholas
LN
Neurosciences Research Institute, School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, United Kingdom.
Mallen
Edward Arthur Harry
EA
Wolffsohn
James Stuart
JS
Gilmartin
Bernard
B
D000293:Adolescent; D000328:Adult; D003315:Cornea / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009907:Optometry / Q000295:instrumentation*; D011237:Predictive Value of Tests; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000175:diagnosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015351:Vision Screening / Q000295:instrumentation*