Purpose
The presence of basal laminar deposits in Bruch’s membrane is a risk factor for the development of age related macular degeneration (Sarks et al., IOVS 48(3), 2007). Polarization-sensitive optical coherence tomography (PS-OCT) is an imaging modality that can potentially identify these deposits in vivo.
Methods
Volumetric PS-OCT data sets centered at the fovea were obtained in 4.4 s in 13 subjects recruited from the Indiana University School of Optometry. The location of the connecting cilia was used as a reference for double pass phase retardation (DPPR) calculation, to avoid contamination from the birefringent cornea, retinal nerve fiber layer, and Henle’s fiber layer. DPPR induced by the deposits was retrieved at approximately 60 µm below the connecting cilia. Data are presented in B-scans and en face projections.
Results
High DPPR signals, up to 180°, were observed immediately beneath Bruch’s membrane of subjects with retinal lesions or subjects who are older (age > 60 years). Figure 1 shows DPPR cross sectional and en face images of a 58-year old subject with retinal lesions and a healthy 38-year old subject. While the intensity images show similar layer structures in the two subjects, the DPPR images reveal obvious retardation differences. In particular, DPPR remained low in Bruch’s membrane of the young subject, but was noticeably elevated at Bruch’s membrane in the older subject, with values approaching 180°.
Conclusions
Older subjects and subjects with retinal lesions often exhibit elevated phase retardation near the RPE/Bruch’s membrane, in sharp contrast to young, healthy subjects who showed no such evidence. We propose that this signal is induced by basal laminar deposits. PS-OCT measurements may be used to monitor the accumulation of deposits in patient eyes and the effect of medication.
Keywords: 412 age-related macular degeneration •
630 optical properties •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)