Abstract
Purpose: :
Geographic Atrophy (GA) , the advanced form of dry agerelated macula degeneration (AMD) causes a severe visual function loss. Foveal sparing can often be observed in the atrophic process.. The aim of the present study is to compare the grading of foveal sparing in fundus autofluorescence(FAF), as the current gold-standard and spectral-domain optical coherence tomography (SD-OCT) in relation to the best-corrected visual acuity (BCVA).
Methods: :
Eightyone eyes of 42 patients (55 to 89 years ) with GA secondary to AMD were examined. Retinal imaging included time-domain optical coherence tomography (TD-OCT, StratusTM OCT), SD-OCT (SpectralisTM HRA+OCT, CirrusTM HD-OCT) and FAF (SpectralisTM HRA+OCT). The foveal region was graded by two independent certified readers from the Vienna Reading Center (VRC) using the afore mentioned devices. The grades were defined as: grade 1 = fovea affected by GA, grade 2 = fovea probably affected, grade 3 = fovea definitely spared. Concordance and discordance of all four imaging methods were evaluated. BCVA was defined as aiding factor: BCVA <0.4 was assumed as fovea affected (grade 1), BCVA ≥ 0.4 was assumed as fovea spared (grade 3). For each imaging method an inter-observer analysis was performed.
Results: :
The agreement between both graders was 93% (75 eyes) for Spectralis HRA+OCT, 79% (64 eyes) for CirrusTM HD-OCT, 68% (55 eyes) for StratusTM OCT and 59% (48 eyes) for FAF.Grade 2 was never used in SpectralisTM HRA+OCT, grade3 was never used in FAF.56% (45 of 81) of all eyes were assumed to have an affected fovea due to a BCVA < 0.4, 44% (36 of 81) of all eyes were assumed to have a spared fovea due to BCVA ≥ 0.4.The validity of BCVA as an aiding factor was reflected in an agreement with the image grader in 59% (48 eyes, grader 1) and 64% (52 eyes, grader 2) for SpectralisTM HRA+OCT, in 65% (53 eyes, grader 1) and 62% (50 eyes, grader 2) for CirrusTM HD-OCT, in 51% (41 eyes, grader 1) and 56% (45 eyes, grader 2) for StratusTM OCT, in 44% (36 eyes, grader 1) and 46% (37 eyes, grader 2) for FAF.
Conclusions: :
Evaluation of foveal sparing was superior with the SD-OCT systems than FAF. This might be due to the fact that in SD-OCT the complete volume of the macula can be evaluated and therefore the precise evaluation of the fovea is easier than in the grey scale FAF image. In uncertain cases BCVA might be of use to evaluate the status of the fovea.
Keywords: age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea