Abstract
Purpose: :
It has been known that optical coherence tomography (OCT) at 1 um wavelength can visualize deep posterior eye such as choroid and sclera. On the other hand, OCT with polarimetric extension (polarization sensitive OCT; PS-OCT) is known to be effective to enhance the contrast of fibrous and birefringent tissues. In this paper, we demonstrate newly developed high-penetration PS-OCT (HP-PS-OCT) with 1 um probe, and investigate the birefringence properties of optic nerve heads.
Methods: :
A prototype HP-PS-OCT that acquires conventional intensity OCT and phase retardation OCT simultaneously was developed. This OCT is based on a swept-source OCT technology and uses a wavelength-sweeping laser at a center wavelength of 1 um and a line rate of 28 kHz. Three healthy human eyes were involved in this study. Volumetric OCT of the optic nerve heads was measured with a raster scanning protocol of 2.8 mm x 2.8 mm in 3.4 s. An OCT intensity image and the corresponding phase retardation image were obtained simultaneously.
Results: :
Three-dimensional structure of pores in lamina cribrosa was visualized in the intensity OCT images. The figure shows representative OCT intensity (left) and phase retardation (right) images of horizontal B-scan. Lamina cribrosa had inhomogeneous birefringence in the optic nerve head. Birefringence of scleral canal rim at the edge of the optic nerve head and that of sclera beneath the choroid were observed.
Conclusions: :
HP-PS-OCT visualized birefringence of deep lamina cribrosa and sclera. Further study may reveal the relationship between inhomogeneous birefringence and structural deformation of lamina cribrosa.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • lamina cribrosa • sclera