Visual function abnormalities and prognosis in eyes with age-related geographic atrophy of the macula and good visual acuity

Abstract

Purpose: Geographic atrophy (GA) may cause significant compromise of visual function, even when there still is good visual acuity (VA), because of parafoveal scotomas and foveal function abnormalities antedating visible atrophy. This study evaluates the visual function abnormalities at baseline and the 2-year worsening of VA and reading rate for eyes with GA compared with a group of eyes with drusen only.

Methods: Seventy-four eyes with GA and VA greater than or equal to 20/50 from a prospective natural history study of GA were included, as were 13 eyes with only drusen. Baseline visual function testing and 2-year VA and maximum reading rate are reported.

Results: The worsening of VA in decreased luminance and foveal dark-adapted sensitivity showed severe abnormalities for the GA group. Contrast sensitivity was significantly reduced for the eyes with GA. Half the eyes with GA, but none of the drusen eyes, had maximum reading rates below 100 words per minute. A scanning laser ophthalmoscope (SLO) measure of the scotoma near fixation combined with a measure of residual foveal function accounted for 54% of the variability in maximum reading rate in the eyes with GA. Of 40 eyes with GA observed for 2 years, half lost greater than or equal to 3 lines of VA and one quarter lost greater than or equal to 6 lines. The nine eyes with drusen with follow-up had no significant change in VA. Low foveal dark-adapted sensitivity, SLO measures of the scotoma within 1 degree of fixation, and low maximum reading rate were statistically significant risk factors for doubling of the visual angle. Significant reduction in maximum reading rates at 2 years was present for the eyes with GA.

Conclusions: The eyes with GA with good VA have profound decreases in visual function, particularly in dim lighting and in reading. Half the eyes with GA had doubling in visual angle at 2 years after the baseline examination, whereas the drusen eyes remained essentially unchanged. Impaired visual function at baseline was predictive of an adverse outcome for the eyes with GA.

Figure 1

(Left) This eye has a small central spared region (arrowhead) surrounded by geographic atrophy. There was a dense scotoma corresponding to the area of atrophy. (Right) Scanning laser ophthalmoscope retinal image of the patient attempting to read the letter ‘Z’ of size 20/240. The letter on the photographed retinal image has been outlined in pencil to improve visibility. The entire 20/240 letter does not ‘fit’ within the central spared region, and the patient was unable to read it. However, she was able to read small letters down to 20/40 in size (because these smaller letters fit into the spared region).

Figure 2

(Left) Fundus photograph of geographic atrophy (GA) at baseline. Visual acuity was 20/29, and maximum reading rate was 110 words per minute. There were areas of GA superior and inferior to the fovea, with a roughly horizontal small spared retinal region (arrowheads). (Center) Scanning laser ophthalmoscope map of dense scotoma at the baseline visit. The white cross in the center of the grid is the fixation cross. The patient does not see the black cross. Solid symbols indicate where the stimulus was seen, and open symbols indicate where the stimulus was not seen (dense scotoma). The symbol may be black or white, depending on the background color. The areas with GA had a dense scotoma, and there was a preserved horizontal strip of seeing retina from the 2 o'clock to the 3 o'clock positions, and from the 9 o'clock to the 10 o'clock positions. There were 3 inner scotoma points, and 39 total scotoma points. (Right) Fundus photograph of GA at 2-year visit. Visual acuity was 20/29, unchanged from the baseline, but maximum reading rate decreased to 51 words per minute. The fundus photograph shows narrowing of the horizontal strip of uninvolved retina (arrowheads) and enlargement of the areas of GA.

Figure 3

(Left) Fundus photograph of geographic atrophy (GA) at baseline. Visual acuity was 20/36 and maximum reading rate was 114 words per minute. There was GA surrounding the fovea from the 3 o'clock position to the 11 o'clock position. The superotemporal extent of the atrophy is shown by the arrows. (Center) Scanning laser ophthalmoscope map of dense scotoma at the baseline visit. The white cross in the center of the grid is the fixation cross. The patient does not see the black cross. Solid symbols indicate where the stimulus was seen, and open symbols indicate where the stimulus was not seen (dense scotoma). The symbol may be black or white, depending on the background color. There was a dense scotoma corresponding to the atrophy, with seeing retina superotemporal to fixation from the 11 o'clock position to the 3 o'clock position. There was 1 inner scotoma point, and 25 total scotoma points. (Right) Fundus photograph of GA at 2-year visit. Visual acuity was 20/58, 2 lines worse than the baseline visit, and maximum reading rate dropped to 7 words per minute. The GA has spread to involve the retina superotemporal to the fovea (arrows). There is a remaining small central spared region (arrowhead), and there is only a narrow spared vertical band at the 12 o'clock position.

Figure 4

(Left) Fluorescein angiogram of geographic atrophy (GA) at baseline. Visual acuity was 20/44, and maximum reading rate was 72 words per minute. The arrows delineate the superonasal extent of the large GA area, and the presence of a small additional area of GA just superior to this region. Several other small areas of atrophy are also present. (Center) Scanning laser ophthalmoscope map of dense scotoma at the baseline visit. The white cross in the center of the grid is the fixation cross. The patient does not see the black cross. Solid symbols indicate where the stimulus was seen, and open symbols indicate where the stimulus was not seen (dense scotoma). The symbol may be black or white, depending on the background color. Fixation at baseline is superior to the large area of GA, just inferotemporal to the small area of GA shown by the middle arrow in Figure 4, left. There was a dense scotoma corresponding to the areas of atrophy. There were 5 inner scotoma points and 31 total scotoma points. (Right) Fundus photograph of GA at 2-year visit. Visual acuity was 20/289, 8 lines worse than the baseline visit, and maximum reading rate was 44 words per minute. The GA has enlarged. The large area of GA has coalesced with the small area of GA superonasally (arrows) and now includes the foveal region.