Is Macular Degeneration just Macular?
Diminished motion perception was used as indicator of early effects of eye diseases in the periphery of the visual field. We investigated whether subtle defects in patients with age-related maculopathy (ARM) can be found in regions of the retina that lie outside the macula, i.e. 10 deg eccentricity. The results showed that such defect can indeed be found. Bottom line: Early ARM already affects areas of the retina that do not belong to the macula.
Purpose -To study the dynamic visual field characteristics in age-related maculopathy (ARMD) we measured motion sensitivity, double-pulse resolution (DPR) and critical flicker fusion in 14 ARMD patients (18 eyes), age-matched controls, and young controls.
Methods - Motion stimulus was a plaid with spatial and temporal Gaussian envelope, moving in one of four directions at a constant velocity (5.7°/s) inside the Gaussian aperture. Motion contrast thresholds were determined by a 4-afc staircase algorithm on the horizontal meridian at 10°, 20°, 30°, 40°, and 60° eccentricity. DPR was measured under photopic conditions using Treutwein`s 9-fold interleaved technique (Treutwein, 1991), with stimuli positioned on concentric rings at 5°, 10°, and 20° eccentricity on the main and oblique meridians, at a total of 25 positions. CFF was measured foveally only.
Results - Motion contrast sensitivity in ARMD patients was pronouncedly reduced (0.23 – 0.66 log units, p< 0.01), not only in the macula but out to at least 20° eccentricity. In the two control groups, motion contrast sensitivity systematically declined with retinal eccentricity (0.009 – 0.032 log units/deg) and slightly with age (0.01 log units/year). Photopic double-pulse thresholds in normals were approximately constant in the central visual field and increased outside a radius of 10° (1.73 ms/deg). DPR thresholds were strongly increased in ARMD patients (by 23 –32 ms, p< 0.01) in the entire test field up to 20° eccentricity, which confirms the findings from motion sensitivity. The foveal CFF was increased in ARMD by 5.5 Hz, or 14% (p< 0.01).
Eisenbarth W, MacKeben M, Poggel DA, Strasburger H. (2008) Characteristics of dynamic processing in the visual field of patients with age-related maculopathy. Graefe’s Arch. Clin, Exp. Ophthal. Jan; 246(1): 27-37 (pubmed, free open access)