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Y. Chang, H.-M. Wu, Y.-F. Lin; The Curvature Relations Between the Lens Surfaces and Measurements of Total Rafractive Power, Radii of Principle Meridians on Ocular Anterior Segment During Accommodation. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4563.
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© ARVO (1962-2015); The Authors (2016-present)
To understand the relations between the radial change of the lens surfaces during accommodation observed in 3D by using MRI technique.
MR imaging system equipped with ocular coil was used to acquire ocular images in 6 healthy subjects with average age of 23.2 +/- 1.1 years. In our previous report lens tilt and decentration as well as shape change on the ocular anterior segment by accommodative stimuli of 60 (F), 40 (M) and 20 (N) cm were demonstrated. One month later, retest was carried out in 5 of the 6 subjects as longitudinal study. Relations in radial changes on both lens surfaces, sectional radii of the principle meridians and total ocular refractive power were measured.
Differences in total ocular refractive power change for F→M, M→N and F→N are 0.79, 3.69, 4.48 D and 0.62, 2.75, 3.33 D in test and retest, respectively. Radial relations between lens anterior surface (y) and posterior surface (x) can be fitted by a simple equation y = -5.27-13271.12 *Exp(-x) with R(sqr) = 0.7995 and significant difference of p = 0.027 in statistical means. In most of cases, statistical tests indicate no significant difference (p < 0.05) is revealed in radial change between accommodative demands for horizontal and vertical meridians, or between the two meridians at the same demands in test and retest.
The 3D MRI technique allows the relations between the components of ocular anterior segment to be simultaneously observed during accommodation. In addition to commonly being noted changes in radius and refractive power, the relations between the two lens surfaces during accommodation is linked and can be fitted by a simple equation with high correlation coefficient.
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