The SVOne is a portable, Hartmann-Shack wavefront aberrometer, which can be attached to a smartphone to determine the refractive error of the eye objectively. Previous results have shown the device to provide measurements equivalent to those of standard clinical techniques in young, healthy adults. The aim of the present study was to compare the findings of the SVOne with retinoscopy, subjective refraction, and two commercially available autorefractors (Retinomax-3 and WAM-5500) in a pediatric population.
The refractive error of the right eye was assessed both without and with cycloplegia in 40 visually normal children between 5 and 17 years of age (mean age = 11.3 years) using the five techniques described above. Further, to assess repeatability of the instruments, the entire procedure was repeated in a subgroup of five subjects. All data were analyzed in terms of power vectors (M, J0, and J45).
No significant difference was observed between the mean values of M (spherical equivalent) for the different techniques. Retinoscopy showed the best agreement with subjective refraction, both without and with cycloplegia, followed by the open-field WAM-5500. The most repeatable procedures, when measured without and with cycloplegia, were the WAM-5500 and retinoscopy, respectively. Measurements with the SVOne showed a decline in repeatability under cycloplegia.
The results indicate that the SVOne provides measurements of refractive error in a normal, pediatric population that are not significantly different from other subjective and objective procedures. Accurate alignment along the visual axis, especially when measuring through a dilated pupil, is critical. This instrument is valuable for vision screenings, for examinations taking place outside the clinical office, and a starting point for the refractive assessment.
*MCOptom, PhD, FAAO
†OD, PhD, FAAO
SUNY College of Optometry, New York, New York (both authors).
Mark Rosenfield, SUNY College of Optometry, 33 West 42nd Street, New York, NY 10036, e-mail: email@example.com