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D.M. Win–Hall, A. Glasser; Comparison Between Objective Accommodation Measurements in Early Presbyopes Using an Autorefractor and an Aberrometer . Invest. Ophthalmol. Vis. Sci. 2005;46(13):721.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Objective measurement of accommodation has become increasingly important in clinical practice. The Grand Seiko WR–5100K autorefractor (GS) has been shown to be a reliable instrument for measurement of accommodation, but few other autorefractors or aberrometers have. In this study, the iTrace wavefront aberrometer (IT) and GS were used to measure accommodation by examining refraction measurements for subjects viewing far and near targets. Methods: 8 subjects, aged 38–40 years old (mean±SD: 40.4±1.92) participated. Distance refraction was measured monocularly while the subjects looked at a distant letter chart. Accommodation was stimulated by a high contrast, self illuminated, near, reduced Snellen letter chart pushed–up to dioptric demands of 2.0, 2.5, 3.0, 3.5 and 4.5 D and the refraction was measured three times each in one eye. Illumination of the target was kept constant by verification with a photometer. The same protocol was followed with the GS and the IT. The entire test was repeated on three different occasions in one same subject. On axis measurements were ensured by directing the subjects to find a letter on the far and near charts that corresponded to the position of the infrared measurement illumination source in both instruments. Results: The range of standard deviations from the three measurements for all amplitudes in all subjects were: GS: 0.01 to 0.62 and IT: 0.07 to 0.69. The range of standard deviations from repeat testing of one subject was: GS: 0.01 to 0.12 and IT: 0.13 to 0.94. An accommodative stimulus response graph of all the data for the GS and IT show them to be not significantly different (F–test = 0.717489; p=0.5169), with the IT recording a greater lag of accommodation. A Bland Altman analysis of the two instruments shows a mean difference between the two instruments of –0.29D and a 95 % confidence interval of 1.11D. Conclusions: The IT accommodative measurements were more variable than those of the GS. In general, the IT measured lower accommodative responses. Objective autorefractors and wavefront sensors need to be validated to determine their suitability and accuracy for objective accommodation measurements.
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