Grading of age-related maculopathy: slit-lamp biomicroscopy versus an accredited grading center

To compare clinical age-related maculopathy (ARM) grading using slit-lamp biomicroscopy (SLB) versus photographic grading of stereoscopically captured fundus photographs (FP) using a high-resolution fundus camera.

A subset (129) of participants in the Carotenoids in ARM study were clinically graded for ARM signs and the corresponding FPs were graded in an accredited reading center.

Drusen were said to be present in 192 (94.5%) eyes graded by FP, and in 165 (82.5%) eyes examined by SLB (agreement = 84%, k = 0.23). A good and modest degree of agreement was observed between SLB and FP for quantification of total drusen number (agreement = 81%, k = 0.33) and for classification of drusen subtypes (agreement = 60%, k = 0.33), respectively. Localization of drusen to either the inner zone or the outer zone was comparable for both techniques of ARM grading (inner zone: agreement = 89%; outer zone: agreement = 88%, k = 0.39). Agreement between SLB and FP was 76% (k = 0.46) for identification of any pigment abnormality; however, agreement was less for hypo-pigmentation abnormalities (agreement = 64%, k = 0.21).

From the statistical perspective, SLB grading of ARM is generally comparable with findings from standardized grading of FP. However, the lower levels of agreement for classification of drusen subtypes and detection of hypo-pigmentation suggest these features may go unrecorded in a study which relies on SLB for grading ARM.