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Abstract #45799 Published in IGR 13-2
Measurement of birefringence of the retinal nerve fiber layer using swept source polarization sensitive optical coherence tomography (1 UM)
Elmaanaoui B; Dwelle J; McElroy A; Paranjape A; Liu S; Rylander H; Milner TLasers in Surgery and Medicine 2010; 42: 16
Background: Glaucoma is the second leading cause ofblindness in the world and is characterized by progressive degeneration and eventual loss of retinal ganglion cells (RGCs) and their axons in the retinal nerve fiber layer (RNFL). Glaucomatous nerve damage usually progresses gradually from the periphery to the central visual field. Since peripheral vision is lost first and symptoms like pain or blurred vision are usually not present; glaucoma is often not diagnosed until a significant vision loss is noticed subjectively by the patient. Since pharmacologic/surgical interventions that slow or stop progressive axon degeneration in the RNFL and prevent additional vision loss are available early diagnosis becomes critical. Swept SOURCE polarization sensitive OCT (SS-PSOCT) can measure viability of the RNFL and possibly serve as an early indicator of Glaucoma. Study: A fiber-based SS-PSOCT and line scan laser ophthalmoscope (LSLO) imaging system was constructed. The system uses a 34 KHz, 60 nm swept SOURCE centered at 1060 nm. The axial resolution is about 10 nm with average incident power on the cornea (425 (square) W below the ANSI maximum exposure level. Five normal volunteers aged 29 to 63 were imaged. An automatic boundary detection and nonlinear fitting algorithm were used to measure RNFL birefringence from the acquired horizontal and vertical fringes. RNFL maps were recorded as ten concentric rings around the optic disk with radii uniformly distributed from 1 mm to 2.5 mm. Registration between RNFL maps was provided by the high contrast vascular fingerprint visualized in the LSLO fundus image acquired simultaneously with SS-PSOCT data. Results: Three sets of peripapillary RNFL thickness, retardation, and birefringence maps of both eyes of the five volunteers were acquired. Conclusion: Changes in birefringence measured by SS-PSOCT has the potential for clinical use as an early diagnostic indicator of glaucoma.
B. Elmaanaoui. University of Texas at Austin, Austin, United States.
Classification:
6.9.1.2 Confocal Scanning Laser Polarimetry (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis > 6.9.1 Laser scanning)
6.9.2.2 Posterior (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis > 6.9.2 Optical coherence tomography)
