Plusoptix Vision Screener: the accuracy and repeatability of refractive measurements using a new autorefractor

Background: The Plusoptix Vision Screener (PVS) is a new non-cycloplegic videoretinoscopy autorefractor. Refractive accuracy may affect its performance as a screening tool. Aims: Study 1: To determine the intra- and interobserver variability of PVS measurements. Study 2: To compare PVS measurements with gold-standard manual cycloplegic retinoscopy (MCR). Methods: Study 1: PVS refraction of 103 children with mean (SD) age 5.5 (0.6) years by two observers. Study 2: PVS and MCR refraction of 126 children with mean (SD) age 5.5 (1.5) years, including 43 children with manifest strabismus >= 5 PD, comparing mean spherical equivalent (MSE) and Jackson cross cylinders J(0) and J(45). Results: Study 1: Repeatability coefficients (observer 1): MSE: 0.63 D, J(0): 0.24 D, J(45): 0.18 D; those of observer 2 were nearly identical. The mean difference (95% limits of agreement) between the two observers for MSE, J(0) and J(45) were, respectively, 0.03 (-0.62 to 0.68 D), -0.008 (-0.25 to 0.23 D) and 0.013 (-0.18 to 0.20) D. Study 2: MSE tended to be lower on PVS than MCR, with differences of up to 8.00 D. Less than 20% of values were within +/- 0.50 D of each other. Agreement was better for J(0) and J(45). Strabismus was associated with an odds ratio of 3.7 (95% CI 1.3 to 10.5) of the PVS failing to obtain a reading. Conclusions: The PVS may underestimate children's refractive error.