Role of Flicker Perimetry in Predicting Onset of Late-Stage Age-Related Macular Degeneration

Figure 1. Flicker visual field test grid used in this study. A, Flicker test grid superimposed on the retina of one of our participants with age-related macular degeneration. The 24 test-point locations are indicated on the 1°, 3°, and 6° rings. Test points are identified serially in a counterclockwise manner starting at the temporal margin of the inner ring, as shown by the numerals (1, 2, 3, . . . 24). Representative flicker threshold outcomes for a normal eye and eye with drusen from part A are shown in parts B and C, respectively. There was a slight reduction in flicker sensitivity in the eye with drusen (C) compared with the normal eye (B).

Figure 2. Participant recruitment flowchart. AMD indicates age-related macular degeneration; CNV, choroidal neovascularization; and GA, geographic atrophy.

Figure 3. Flicker sensitivity and the rate of change seen during an 18-month follow-up in a representative eye with clinically detectable geographic atrophy (GA), detected 18 months after the initial visit. A, Fundus photograph showing the location of GA (arrowhead), with the magnified view of the atrophic area shown in the insert. B, The flicker visual field for the visit when GA was detected. Reduction of the flicker sensitivity over the atrophic area is evident in position 1. The flicker sensitivity was also markedly reduced in areas surrounding the GA where no GA is clinically present. C, Rate of change in flicker sensitivity over time. The rate was much greater in the area that became atrophic as well as in several other retinal positions. D, Examples of rate of change in flicker sensitivity in a progressing area (position 1 in part C) and a stable location (position 18 in part C) during the follow-up period. Black and red lines represent raw data and a linear fitted trend, respectively.

Figure 4. Fundus photographs (A-C) and flicker sensitivity (D-F) 6 months before, at diagnosis of clinically detectable geographic atrophy (GA), and 6 months later. The atrophic regions have been outlined on the fundus photographs (B and C). Significant reduction of flicker sensitivity was observed not only at the time when GA was clinically detected (E) but also at 6 months before the detection of GA (D). Further reduction of flicker sensitivity was associated with GA progression (F). The flicker sensitivity of the areas surrounding the existing atrophy was also significantly reduced and correlated with the expanded area of GA (E and F). The rate of change in flicker sensitivity 6 months before GA (ie, changes in flicker sensitivity between D and E) and after GA (changes in sensitivity between E and F) is shown in parts G and H, respectively. In this instance, the rate of change in flicker sensitivity increased significantly following the development of GA.

Figure 5. Color fundus photograph and the flicker sensitivity of a representative eye with clinical geographic atrophy (GA) that evolved during 5 years of follow-up. The atrophic region is within the outlined areas. At baseline (t = 0), when GA was clinically undetectable (A), there were already areas of reduced sensitivity that correlated with the new area of atrophy detected 2.5 years later (B). When GA was detected (B), the flicker sensitivity was significantly reduced in the atrophic area. There was also a reduction in sensitivity in the surrounding nonatrophic areas. The nonatrophic region with abnormal sensitivity shown at t = 2.5 years (B) went on to develop GA some years later (C).

Figure 6. Color fundus photograph and the flicker sensitivity of a representative eye with choroidal neovascularization (CNV). A reduction in flicker sensitivity was observed 6 months before clinical detection of CNV (A). Further reduction in flicker sensitivity was seen when CNV was detected (B). The rate of change in flicker sensitivity during the 18 months before CNV detection showed a small decline in flicker sensitivity over a few locations.

Figure 7. Color fundus photograph and the flicker sensitivity of another eye with choroidal neovascularization (CNV). Reduction in flicker sensitivity was detected in only a few positions before (A) and after (B) CNV was detected. Again, the rate of change in flicker sensitivity during the 18 months before CNV detection (C) showed minimal changes in sensitivity in most of the positions.