Abstract
Purpose :
The micro-structures and circulation in optic nerve head (ONH) are expected to be associated with glaucoma and myopia. However, there was no modality which can measure the micro-structure of ONH in vivo. Jones matrix OCT (JM-OCT) is an emerging modality which can image the ocular tissue and also can quantitatively measure the several optical properties in vivo. It includes scattering coefficient (SC), birefringence (BR), polarization uniformity (PU), and flow (OCTA). Since the SC and BR are associated with tissue micro-structure, JM-OCT can assess the micro-structure in vivo. Here we investigate the relationship among the optical properties of ONH tissues and demographic and biometric parameters.
Methods :
A custom-build posterior JM-OCT with a 1-µm probe was used in this study. JM-OCT provides the above mentioned 4 optical properties by a single scan. SC, BR, and PU are known to be associated with tissue density (SC), collagen content (BR), and melanin (PU). Right eyes of 6 non-glaucomatous subjects (37.2 ± 10.3 y/o, mean ± SD) were measured by JM-OCT. Six regions of interest (ROIs) are manually selected in a horizontal cross-section around the ONH center. The ROIs are lamina cribrosa (LC), prelaminar region (PL), nasal and temporal scleral canal rims (NSCR and TSCR), and nasal and temporal nerve fiber layers (NNFL and TNFL). The correlations among the average optical properties within the ROIs, age, refractive error (RE), and intraocular pressure (IOP) are evaluated.
Results :
The mean IOP, RE are 16.2 ± 1.5 mmHg, and -4.3 ± 3.1 D, respectively. LC’s BR was correlated with OCTA of TSCR (r = -0.95, p = 0.003), and RE (r = -0.82, p = 0.044). LC’s OCTA was correlated with BR of NNFL (r = -0.85, p = 0.032), OCTA of NSCR (r = 0.90, p = 0.013), and age (r = -0.85, p = 0.035). PL’s BR was correlated with PL’s OCTA (r = -0.82, p = 0.046) and age (r = 0.92, p = 0.01).
Conclusions :
Although no direct correlation was found between LC and PL, both tissues are correlated with age through OCT (LC) and BR (PL). It is an in-vivo measureable evidence of age-related alterations of these tissues. Myopia seems to affect the collagen microstructure of LC as suggested by its BR. The microstructure of LC seems to be associated with the microstructure of sclera. Since both tissues are collagenous, this relation is plausible. These relations are summarized in the figure.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.