Validation of a partial coherence interferometry method for estimating retinal shape

Abstract

Abstract:To validate a simple partial coherence interferometry (PCI) based retinal shape method, estimates of retinal shape were determined in 60 young adults using off-axis PCI, with three stages of modeling using variants of the Le Grand model eye, and magnetic resonance imaging (MRI). Stage 1 and 2 involved a basic model eye without and with surface ray deviation, respectively and Stage 3 used model with individual ocular biometry and ray deviation at surfaces. Considering the theoretical uncertainty of MRI (12-14%), the results of the study indicate good agreement between MRI and all three stages of PCI modeling with <4% and <7% differences in retinal shapes along horizontal and vertical meridians, respectively. Stage 2 and Stage 3 gave slightly different retinal co-ordinates than Stage 1 and we recommend the intermediate Stage 2 as providing a simple and valid method of determining retinal shape from PCI data.

Three-dimensional MRI study of the relationship between eye dimensions, retinal shape and myopia

“…There were 28 emmetropes with right eye spherical equivalent refraction in the range + 0.75 D to −0.62 D and 30 myopes (-0.75 D to −8.25 D). Some results for the participants have been reported previously [22]. Table 1 shows refraction characteristics related to race and gender.…”

“…Following this, a T2-weighted Half-Fourier-Acquisition Single-Shot Turbo Spin-Echo (HASTE) sequence was employed to generate 3D isotropic images of the eye with 0.5 mm cubic voxels (128 × 128 × 64 matrix; TR = 2500 ms; TE = 56 ms; imaging time 4 min). Limitations of the method associated with the dimensions of voxels have been discussed previously [22].…”

“…MRI data were analyzed using custom written MATLAB (Mathworks, Natick, MA) software in three major steps detailed previously [22]: 1. Image rotation to a common z-axis (visual axis), 2.…”

“…Retinal shape can be estimated by indirect optical methods that are based on peripheral refraction [11][12][13], partial coherence interferometry [14][15][16][17][18][19][20][21][22][23][24] and optical coherence tomography [25,26]. However such methods rely on assumptions concerning shape and refractive index distribution through the lens and other structures within the eye, in order to convert optical path lengths into geometrical dimensions.…”

Change in human lens dimensions, lens refractive index distribution and ciliary body ring diameter with accommodation

“…All had < 1.5 D astigmatism. These people were part of a larger group of 60 participants [11]; thirteen participants could not be included because accommodation images were not acquired, and for nine participants some images had significant motion artifacts (three without, and six with accommodation).…”