Cynthia A. Toth, MD (Durham, NC), Marcin Stopa, MD (Poznan, Poland), Joseph Izatt, PhD (Durham, NC),* Bradley A. Bower, PhD (Durham, NC), Brian Dodge, (Durham, NC)


Pathology data from three-dimensional imaging of the fundus with spectral domain optical coherence tomography (SDOCT) can be extracted, cross-correlated with conventional retinal imaging and retinal function data, and can be precisely monitored over time. Such data would be useful in identifying physical outcome measures and markers of progression in age-related macular degeneration (AMD).


In a prospective study, patients with nonneovascular and neovascular AMD had fundus imaging with conventional OCT and with the SDOCT system. The superluminescent diode source was at 840 nm (??? 49 nm, coherence length in tissue 4.7 μm). 3D retinal data blocks (512 axial x1000 x100 lateral voxel images) were acquired in 5.7 seconds. OCT data were analyzed to determine precise location of focal retinal pathology compared to conventional imaging that had been performed in evaluating the retinal disease. Scans were assessed for motion artifact and use in defining location and extent of soft drusen, geographic atrophy (GA), neovascularization (CNV), cystoid macular edema and subretinal fluid.


Because of the rate of acquisition, motion artifact was not an issue in the SDOCT scans, while it was a confounder in evaluating drusen and pigment epithelial detachments in conventional OCT. Although some drusen and most GA and CNV were visible on
conventional OCT imaging, the location, number and size of drusen, GA and CNV could not be determined from those studies. Both small and large drusen could be resolved on the SDOCT system and these could be precisely located and compared to the corresponding autofluorescence image or fundus photograph or angiogram. Different patterns of reflectivity could be identified within soft drusen on the SDOCT images. SDOCT imaged focal sites of subtle thinning of the photoreceptor layer, that were missed with conventional OCT. Retinal thickening and subretinal fluid defined by SDOCT extended outside areas of abnormal
fluorescence in late frames of corresponding fluorescein angiograms.


In age-related macular degeneration, SDOCT imaging of drusen and neovascularization reveals pathology not visible with conventional imaging techniques, and provides a unique opportunity to localize and assess focal morphologic changes and moniter these sites over time.
* Financial interest disclosed