Spherocylindrical refraction performed with the Vmax Voice Activ Subjective Refractor yielded results that were not statistically different from those achieved using a traditional phoropter.
Christopher Lievens, OD, MS, FAAO, and colleagues reported that 50 subjects were examined first with the Nidek TonoRef II followed by subjective refinement by an experienced optometrist with a phoropter, then by a second-year optometry student using the Vmax Voice Activ Subjective Refractor (VASR) to produce an objective and subjection refraction.
Subjects were at least 18 years old and wore spectacles or soft contact lenses.
No statistically significant difference was found from the mean in equivalent sphere measurements, according to their poster presented at the Association for Research in Vision and Ophthalmology meeting.
Values for traditional refraction ranged from +1.13 D to -12.75 D and for VASR from +1.08 D to -14.39 D. The spherical equivalent datasets, cylinder power and axis were highly correlated, according to the study.
The researchers reported the visual acuity measurements were similar – 18% had better acuity and 3% had worse acuity with VASR. They noted that the VASR required 71 additional seconds, on average, to complete.
Vmax Vision CEO Shui Lai, PhD, stated in a press release from Vmax, “The study showed that the difference in the median refraction values between the Vmax measurement and the phoropter measurement is 0.19 D, and the 95% confidence intervals for the two methods are almost completely overlapped (-1.26 to -3.46), a clear indication the VASR and phoropter results showed no statistical difference in outcomes. The VASR method has a higher percentage in better visual acuity; one line or more, in 14% of the subjects vs. the phoropter method produced better visual acuity in 3% of subjects, and the rest are within one line of visual acuity.
“Put another way,” he continued, “the VASR measurements produced equal acuity in 97% of the subjects when compared with phoropter refraction.”
Lievens told Primary Care Optometry News, “It should be noted that the VASR does not perform binocular testing, whereas a traditional manifest refraction routinely does so.” – by Nancy Hemphill, ELS, FAAO
Lievens C, et al. Comparison of the Vmax Voice Activ Subjective Refractor and traditional refraction in a healthy population. Presented at: Association for Research in Vision and Ophthalmology; Honolulu; April 29-May 3, 2018.
Disclosure: Lievens reported no relevant financial disclosures. Lai is employed by Vmax.