Purpose
To identify a potential topographic relation of evolving reticular pseudodrusen (RPD) to choroidal watershed zones (CWZ) as well as to local changes in choroidal thickness (CT) and choroidal volume (CV).
Methods
20 eyes of 20 patients with RPD in the posterior pole in an area < 10 mm2 and no other phenotypic retinal alteration were included (16 females, 4 males; age 75.9 ± 7.0 years). Patients underwent fundus photography, spectral domain optical coherence tomography (SD-OCT), enhanced depth imaging OCT (EDI-OCT), fluorescence videoangiography (vFA), indocyanine green videoangiography (vICG) and confocal scanning laser ophthalmoscopy (cSLO) (Fundus autofluorescence [FAF, λ = 488 nm], near-infrared reflectance [IR, λ = 830 nm]) (Spectralis, Heidelberg Engineering, Germany). vICG were evaluated for the presence, localization and configuration of CWZ. Retinal areas affected by RPD were measured and their localization was determined in relation to CWZ. Cursor lines marking the internal limiting membrane and the retinal pigment epithelium (RPE) in EDI volume scans were moved manually to the outer border of the RPE and the choroidal-scleral interface to construct a CT map of the posterior pole. CT and CV were measured using the ETDRS grid. An age and sex-matched control group of 20 healthy eyes underwent the same procedures.
Results
In all study eyes, RPD and no other retinal alteration could be clearly demonstrated in SD-OCT, EDI-OCT, vFA, vICG and cSLO. CWZ were identified in 17 eyes (85.0%) in the study group and in 7 eyes (35.0%) in the control group. The area affected by RPD in the study group was 7.58 ± 2.39 mm2. In 17 study eyes showing CWZ the RPD area was fully or partly located within the CWZ in 15 eyes (88.2%). Mean CV in the full ETDRS grid area was 4.76 ± 1.93 mm3 in the study group and 4.74 ± 1.24 mm3 in the control group. CV and CT in the grid sector mostly affected by RPD were 0.96 ± 0.37 mm3 / 181 ± 70.7 µm and 1.1 ± 0.3 mm3 / 207 ± 57.9 µm in the corresponding sector of the control eyes.
Conclusions
The localization of evolving RPD seems to be related to the presence and the site of CWZ. However, an association between the presence of RPD and macular CT and CV could not be shown in this population.
Keywords: 412 age-related macular degeneration •
504 drusen •
550 imaging/image analysis: clinical