Southern College of Optometry Reported at ARVO 2018 a Study Comparing the Accuracy of Subjective Refraction Using a Vmax Vision's VASR™ vs. a Traditional Refraction
HONOLULU, May 17, 2018 /PRNewswire/ -- A comparison study was reported at ARVO 2018, which has recently concluded in Honolulu, Hawaii. Drs. Christopher Lievens, Christina Newman, Alan Kabat and optometry student Jacob Weber conducted this study at the Southern College of Optometry (SCO). This study included 50 healthy subjects. Subjects were examined by a masked investigator using a standard autorefractor (Nidek TonoRef™ II) followed by subjective refinement using a standard phoropter (monocular subjective refraction with binocular balance). Subjective measurements were also conducted in the corresponding subjects using the VASR, a Voice Activ Subjective Refractor by Vmax Vision.
Phoropter values were measured in 0.25 diopter steps, while VASR data was refine-able to the nearest 0.01 diopters. Final corrected visual acuity was recorded for each eye after each procedure using standard Snellen targets. The phoropter measurements were conducted by faculty members at SCO (Lievens, Newman and Kabat) and the VASR subjective measurements were conducted by an optometry student (Weber).
The results revealed that there was no statistically significant difference from the mean in equivalent sphere measurements (p = 0.1383) between Vmax VASR and the phoropter. Non-parametric analyses (Wilcoxon) were performed as there was a negative skew and the data was platykurtic. Dioptric values for traditional refraction ranged from +1.13 to -12.75 (95 percent confidence interval = -1.63 to -3.63), with a median of -2.50. The VASR, values ranged from +1.08 to -14.39 (95 percent confidence interval = -1.26 to -3.46), with a median of -2.69. The spherical equivalent datasets were highly correlated (r = 0.993); cylinder power and axis were as well (Cylinder: p = 0.6377, r = 0.864) (Axis: p = 0.6991, r = 0.738). Visual acuity measurements were similar for both groups: 14 percent of subjects had better acuity with VASR (> 1 line Snellen), three percent of subjects had worse acuity with VASR (>1 line Snellen), and 83 percent had less than 1 line Snellen difference.
For spherocylindrical refractive error, the results obtained with the Vmax VASR by a second-year optometry student with two hours of training were not statistically different from those achieved using traditional phoropter methods by an SCO optometrist and faculty member. This indicates that the training requirement to refract with the VASR is substantially easier than training to refract using a phoropter, which takes several months (or even years).
Dr. Shui Lai, Ph.D., CEO of Vmax Vision, stated, "The study showed that the difference in the median refraction values between the Vmax measurement and the phoropter measurement is 0.19D and the 95 percent confidence intervals for the two methods are almost completely overlapped (-1.26 to -3.46); a clear indication the VASR and the phoropter produced essentially identical outcomes. The VASR method has a higher percentage in better visual acuity (VA) - one line or more in 14 percent of the subjects vs. the phoropter method which produced better VA in three percent of the subjects, and the rest are within one line of VA. Put another way, the VASR measurements produced equal or better acuity in 97 percent of the subjects, when compared with phoropter refraction."
The VASR (Voice Activ™ Subjective Refractor) autorefraction utilizes wavefront aberrometry and its subjective refraction uses proprietary point spread function technology. The VASR exam is voice-guided during the entire refraction and it combines artificial intelligence to optimize refraction outcomes. Other advanced features include subjective nighttime refraction, four-minute complete auto and subjective refraction in normal sighted patients; increasing patient flow. The VASR's small footprint of 12' by 18" reduces a refraction lane to a tabletop station. The low weight and small in size make it ideal for portability.
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