Image registration and multimodal imaging of reticular pseudodrusen

Purpose. To characterize reticular pseudodrusen (RPD) by using a point-to-point comparison of the reticular pattern on infrared reflectance (IR), autofluorescence (AF), and red-free (RF) images registered with en face sections of the choroid from spectral domain optical coherence tomography (SD-OCT) scans. Methods. A cross-sectional, retrospective study of all patients with the diagnosis of AMD who presented to the Doheny Retina Institute between December 2007 and November 2009 was conducted to identify patients with RPD. IR, AF, and RF images were obtained using confocal scanning laser ophthalmoscopy and were manually registered to OCT choroidal sections to study the location of RPD. The main outcome measured was point-to-point localization of RPD across multiple imaging modalities. Results. Of the 153 patients with AMD, 51 had RPD. In all 51 patients (97 eyes), RPD appeared as areas of hypoautofluorescence and hyporeflectance on AF and IR imaging, respectively, and as hyporeflective interlacing networks on RF. Reticular lesions on AF, IR, and RF images consistently colocalized with stromal regions between large choroidal vessels on registered en face choroidal sections. In contrast, outer retinal changes and subretinal deposits tended to localize immediately adjacent to the RPD. Conclusions. Point-to-point correlation of registered IR, AF, and RF images consistently localizes the reticular pattern to the intervascular choroidal stroma on en face OCT sections. In contrast, subretinal deposits and disturbances of the inner outer segment on OCT did not colocalize with the RPD, and may represent secondary mechanical or biologic disturbances in the overlying RPE and outer retina.