Purchase this article with an account.
N.S. Logan, K.D. Singh, B. Gilmartin; 3D Conformation of Human Eye Shape Using MRI . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4266.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Previous studies have used computer modelling, optical low coherence reflectometry and magnetic resonance imaging (MRI) to depict a 2–dimensional representation of the posterior vitreous chamber and demonstrate that retinal shape varies in ametropia. In general myopic eyes exhibit prolate elongation compared with emmetropes although considerable inter–subject variation is evident. We extend further the utility of MRI in assessing structural correlates of ametropia by generating 3–dimensional conformations of human eyes. Methods: An internal 3D image of the eye has been acquired using a Siemens Trio 3–Tesla MRI Scanner with sequences that have been optimised for revealing detail in the eye. A T2 weighted image allows generation of an envelope of the eye to which a shrink–wrap and smoothing algorithm have been applied. The resulting 3D envelope of the eye can be used to measure axial length, ocular volume and nasal versus temporal asymmetry in the vitreous chamber. The method has been applied to both eyes of 6 subjects, age range 25 – 39 years, range of refractive error +4.00 to –9.00D. The imaging and analysis methodology also allows both visualisation and an ability to rotate the model in real–time enabling viewing of the eye from any angle. In addition morphological parameters of interest using local radius of curvature of the surface of the eye can be calculated. Results: Axial lengths from the MR images corresponded to those measured using the Zeiss IOLMaster (r=0.98, p<0.001). Ocular volume was found to increase with axial length (r=0.95, p=0.01). Nasal versus temporal asymmetry (nasal steeper) in curvature of the vitreous chamber was evident in all subjects, confirming findings from previous computed eye shapes (Logan et al. IOVS 2004; 45: 2152–2162). Conclusions: The new methodology allows manipulation of the spatial orientation of a complete, in vivo, 3–D representation of the eye; associated measures of ocular shape and volume; indices of regional expansion that may correlate with degree of myopia.
This PDF is available to Subscribers Only