Abstract
Purpose:
To characterize subretinal drusenoid deposits (SDD), also known as reticular pseudodrusen, using en face spectral-domain optical coherence tomography (SD-OCT)
Methods:
Consecutive eyes with pseudodrusen appearance were examined using near-infrared reflectance (NIR) confocal scanning laser ophthalmoscopy (SLO) and eye-tracked SD-OCT. SD-OCT images were acquired with the Heidelberg Spectralis using a pattern size of 20x25° with 241 sections, each composed of at least 19 averaged B-scans at 30 µm intervals and analyzed using a newly integrated transverse section software. En face OCT scans were correlated with cross-sectional B-scans and NIR-SLO images. For classification of SDD a previously proposed grading system was used which is based on their cross-sectional appearance.
Results:
The study included 95 eyes of 73 patients (57 female, 16 male) with SDD. In 83 eyes (87.4 %) soft drusen were also present. SDD at stage 1 was present in all eyes, stage 2 SDD occurred in 33 eyes (34.7 %), stage 3 SDD was graded in 62 eyes (65.3 %). Morphologic features of SDD in en face OCT scans ranged from hyperreflective roundish lesions with or without a hyporeflective annulus to interconnecting homogenous moderately reflective branching structures depending on the height of the en face OCT-scan in relation to the retinal pigment epithelium (RPE) and the drusen stage. SDD at stage 3 appeared as roundish homogenous hyperreflective lesion usually surrounded by a ring-shaped hyporeflective zone (annulus). Of en face OCT scans exhibiting hyporeflective annuli, 96.6% contained SDD at stage 3. We did not find any association between best corrected visual acuity and en face SD-OCT features.
Conclusions:
Conventional SD-OCT macular cube scans may fail to display SDD with adequate resolution. Using the recently integrated transverse section software analysis of Spectralis the interlacing network and the distribution of SDD can be visualized. As en face images of eyes containing hyporeflective annuli do include a high probability having stage 3 SDD, characteristic findings allow conclusions on the present stage. Transverse section analysis displaying SDD can provide useful additional information to classify SDD more accurate and might be important for automated macular analyses in future epidemiologic studies.