Retinal Sensitivity in Areas of Reticular Drusen as Measured by Microperimetry
Purpose: Reticular drusen, appearing as yellowish drusen in an interlacing pattern, have an unclear clinical significance in affected patients. To better understand how reticular drusen impacts local retinal function, we measured retinal sensitivity in affected retinal areas using microperimetry.
Methods: Patients with intermediate to advanced age-related macular degeneration (AMD) at the National Eye Institute Clinical Center were evaluated for the presence of reticular drusen using color fundus photographs and autofluorescence images. Eyes with reticular drusen (n = 18 eyes in 13 patients) underwent retinal sensitivity evaluation on the MP1 microperimeter (Nidek, Padua, Italy). A circular pattern of testing loci centered on the fovea and aligned on the horizontal raphe was used; a pattern of radius 20 degrees (61 points) was used in 16 eyes, and another pattern of radius 10 degrees (68 points) was used in 2 eyes. Areas of reticular drusen were circumscribed and measured by a masked grader using imaging software (NIH ImageJ). Testing loci in areas of reticular drusen were compared with control loci of equal eccentricity from the horizontal raphe located outside the area of reticular drusen. Testing loci in which the stimulus was not projected or located in areas of retinal/RPE atrophy were excluded from the analysis.,/p>
Results: Study eyes ranged in visual acuity from 20/20 to 20/400. Mean retinal sensitivity of all loci in areas of reticular drusen was 9.39±3.14dB (n = 157 loci in 18 eyes) compared to 12.9±4.76db (n = 157 loci in 18 eyes). Pairwise comparisons of reticular drusen loci to control loci demonstrated a statistically lower retinal sensitivity in reticular drusen loci (p<0.001, paired t-test). Mean retinal sensitivity in each area of reticular drusen (n = 18 areas in 18 eyes) were also computed. A trend towards a correlation between increasing area of reticular drusen and decreasing mean retinal sensitivity was observed (p = 0.151).
Conclusions: Retinal areas with reticular drusen are associated with decreased retinal sensitivity, indicating a negative impact of reticular drusen on local retinal function. A possible association between the size of the area affected and sensitivity decrement also suggests that this negative impact may incrementally increase with time and reticular drusen development. Longitudinal studies involving scotopic microperimetry or dark adaptation can further elucidate the functional significance of reticular drusen.