Three–Dimensional High–Speed High Resolution Fourier–Domain Optical Coherence Tomography for Volumetric Analysis of Retinal Structures

Abstract

Purpose: : To make volumetric analyses of retinal structures in various clinical disorders using high–speed ultra–high resolution Fourier–domain OCT (Fd–OCT).

Methods: : Five patients with glaucoma, and 5 patients with macular edema were imaged with Fd–OCT system built at the UC Davis Medical Center to acquire volumetric representations of their retinas. Axial data was acquired by the use of two superluminescent diodes as light sources, SLD1 and SLD2. The measured axial resolution on the retina was about 6µm for SLD1 ( 840@50nm), and 3.5 µm for SLD2 (890@150nm). The lateral resolution was calculated to be in the range of 10 to 15 µm for most of our subjects. The B–scans were acquired in 1000 A–scan frames with 100 µs exposure time per A–scan, resulting in data acquisition and real–time post processing of 9 frames per second (fps) display and acquisition speed. A set of 100 B–scans were acquired for each patient covering 6 x 6 x 2 mm volume of retina (lateral x lateral x depth). After acquisition of a full set of B–scans, these data were registered for eye movements, segmentation was performed to isolate structures of interest: nerve fiber layer for glaucoma patients and outer retinal layers for macular edema. Analyses were then performed on these data to measure the volumes of the segmented retinal structures.

Results: : Fd–OCT was able to acquire accurate volumetric representations of the retina that were then used to calculate volumetric measurements of the retinal structures of interest in both glaucoma and macular edema.

Conclusions: : Fd–OCT is a reliable non–invasive technique that can be used to perform volumetric analyses of retinal structures that may aid in the evaluation and treatment of glaucoma and macular edema.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical