Plusoptix Vision Screener : the accuracy and repeatability of refractive measurements using a new autorefractor
(Précisions et répétitivité des mesures de la réfraction en utilisant un nouvel autoréfractomètre : le Plusoptic Vision Screener)

Dahlmann-Noor AH, Comyn O, Kostakis V, Misra A, Gupta N, Heath J, Brown J, Iron A, McGill S, Vrotsou K, Vivian AJ.
Eye Treatment Centre, West Suffolk Hospital NHS Trust, Hardwick Lane, Bury St Edmunds IP33 2QZ, UK.

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.

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