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Florence Cabot, Victor Hernandez, Fabrice Manns, Sonia H Yoo, Arthur Ho, Jean-Marie A Parel; Evaluation of a real-time Hartman-Shack based autorefractor. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2717.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the repeatability and comparability of objective refraction obtained with two commercially available devices: iTrace (Tracey Technologies, Houston,TX), ARK-760A (Nidek, Tokyo, Japan), and a prototype Hartmann-Shack based autorefractor designed to allow real-time measurements with large dynamic range.
Prospective comparative study including 42 eyes of 21 healthy patients. Each patient underwent 3 measurements of refraction on each eye with each of the following devices: iTrace, ARK-760A and a prototype Hartmann-Shack based autorefractor built in-house (Figure 1). The prototype device is a modification of a slit-lamp mounted HS-AR designed without the traditional 4f relay system (Beverage and Schwiegerling, J Ref Surg 2006). The modified design uses a compact relay system that increases the measurement range by imaging a reference plane located in front of the eye onto the lenslet array. All tests were performed by the same trained operator. Objective refraction including sphere, astigmatic power and axis was recorded with the three devices. Spherical equivalent was calculated. The Bland-Altman method was used to assess the agreement in variables between the 3 devices.
: Bland-Altman plot of sphere values shows a mean difference (+/-2SD) of -0.17+/-2.28D between the prototype autorefractor and ARK-760 and a mean difference (+/-2SD) of -0.06+/-2.84D between the prototype autorefractor and the iTrace. Bland-Altman plot of astigmatic power values shows a mean difference of -0.58+/-1.51D between the prototype autorefractor and ARK-760 and a mean difference of -0.45+/-1.13D between the prototype autorefractor and the iTrace.
The measurements obtained with the prototype Hartmann-Shack based autorefractor are consistent with those obtained with the 2 commercially available devices.
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