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Viswanathan Ramasubramanian, Adrian Glasser; Can Accommodation in Pre-Presbyopic Population be Predicted Accurately with Ultrasound Biomicroscopy?. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3773.
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© ARVO (1962-2015); The Authors (2016-present)
Previously, in a young population of 25 subjects, the accommodative optical response (AOR) was predicted from the population linear regressions of ultrasound biomicroscopy (UBM) measured ocular biometry parameters with a variance of less than 0.50 D. The goal here was to establish the accuracy of using UBM to predict the AOR in a pre-presbyopic population with lower accommodative amplitudes.
The population was 25 subjects aged 35 to 45 (mean ± standard deviation (SD): 40.8 ± 3.08) years, with at least 1 D of objectively measured AOR. Static AOR to stimulus demands of at least 0.25 D equally spaced intervals were measured with a Grand-Seiko (GS) autorefractor (WR-5100K). Subsequently, a 35 MHz UBM (Sonomed Escalon VuMAX) was used to image the left eye, while the right eye viewed the accommodative stimuli. The ocular biometry parameters were measured from the UBM images using automated Matlab image analysis. UBM images were calibrated by imaging five rigid contact lenses (CL) of known front and back surface radii of curvature at various distances from the transducer to correct for spatial distortion of the anterior and posterior lens surfaces.
Root mean square error of radius/power of the front and back CL surfaces after distortion correction were 0.22 mm/1.15 D and 0.17 mm/1.32 D, respectively. Statistically significant linear regressions fit to the data yielded per-diopter accommodative biometric changes of: anterior chamber depth (ACD): -52.6 µm/D; lens thickness (LT): 73.4 µm/D; posterior lens surface movement (PLM): 34.9 µm/D; anterior and posterior lens radii of curvature (ALRC & PLRC): -1090 µm/D and -186 µm/D respectively. The mean SD of biometric measurements for all subjects for all AOR were: ACD: 18 µm; LT: 27.7 µm; PLM: 33.8 µm; ALRC: 467 µm; PLRC: 173 µm. From population linear regressions, the SD of the AOR calculated from 1 SD of each UBM measured biometry parameter was: ACD: 0.16 D; LT: 0.28 D; PLM: 0.43 D; ALRC: 0.09 D; PLRC: 0.38 D. The mean variance in predicting AOR from biometry in this population using the 95% confidence interval is: ACD: 0.29 D; LT: 0.18 D; PLM: 0.53 D; ALRC: 0.39 D; PLRC: 0.46 D.
UBM measured biometry parameters can, on average, be used to predict AOR in a population with a variance of less than 0.55 D. This study demonstrates that UBM is a useful objective technique for measuring accommodation in older phakic eyes.
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