Abstract
Purpose :
In early cataracts, the crystalline lens presents some subtle opacifications causing an increase in scattering and a reduction in quality of vision. We have developed a long-range swept source OCT utilizing short external cavity wavelength tunable laser technology for in vivo three-dimensional (3-D) imaging of the crystalline lens to detect opacifications.
Methods :
A high speed swept-source OCT instrument operating at 1050 nm for long-range imaging was developed and optimized for full anterior segment visualization. Imaging of the cornea and the crystalline lens at 50 kHz axial scan rate with 17 mm depth range was performed. OCT volumetric data sets consisting of 350x350 A-scans and covering 7x7 mm2 area (iris area) were acquired. Different contrast parameters were explored in post-processing to effectively visualize the opacities in the crystalline lens. 3-D rendering of spatially resolved scattering within the lens were produced.
Results :
We characterized the performance of the OCT system to minimize signal drop with depth (-6 dB at 10 mm depth) and achieve high sensitivity (102 dB). The swept light source used in the OCT system had enhanced coherence length leading to low signal drop. We obtained volumetric OCT tomograms spanning the depth of the entire anterior segment for 3-D visualization of the scattering properties of the crystalline lens. The opacities are characterized by enhanced scattering and generate shadows in cross-sectional images of the crystalline lens, which enables their effective mapping. Eyes with different types and degree of cataract severity were measured.
Conclusions :
3-D long-depth-range Swept-Source OCT enables volumetric visualization in vivo microstructural changes in the crystalline lens related to opacification. This instrument might be a useful tool in the evaluation and management of crystalline lens opacities in cataract patients.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.