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Thomas Forshaw, Sten Andreasson, Torben Lykke Sørensen; Age-related Macular Degeneration: a generalised retinal disorder A prospective study of retinal function using full-field electroretinography. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1163.
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Age-related macular degeneration (AMD) is generally considered a macula “cone” disease. However,patients with AMD have impaired retinal function on full-field electroretinography (ffERG) compared with those with healthy retina, even though the macula accounts for only a small part of the ffERG. Studies have shown impaired dark adaptation in patients with AMD, suggesting potential rod dysfunction. We wanted to study if there is a more generalised affected retinal function in AMD patients compared to healthy, and also study the correlation between visual acuity (cone function) and dark adapted ffERG (rod function) in patients with AMD.
We performed ffERG in 32 AMD patients diagnosed by fundus examination, and 14 patients without vitreoretinal disease as control group. All patients had bilateral cataract. Patients were recruited from the outpatients department of a university teaching hospital. Average age was 78 years in the AMD group (N) and 72 years in the control group (N1). VA was measured using the ETDRS scale. ffERG was performed binocularly according to ISCEV standards using a Ganzfeld stimulator and DTL fibre electrodes. Dark-adapted 3.0 cone-rod response was obtained. ffERG recording and VA from the right eye was used, unless a patient only had AMD in the fellow eye, in which case the left eye was used. Total number of eyes was 46 (N=32; N1=14). Patients were excluded from the study if they had amblyopia, a retinal pathology other than AMD, or glaucoma with visual field defect. Statistical analysis was performed using SPSS.
Fig 1 shows negative correlation between dark-adapted implicit time in the a-wave and VA in the AMD group (P=0.067). There appears to be no such correlation in the control group. Fig 2 shows positive correlation between dark-adapted a-wave amplitude and VA in both groups (P=0.053).
Correlation between global photoreceptor function and visual acuity suggests AMD is a generalised disorder affecting the retina as a whole. Increased magnitude of the a-wave response has a positive effect on VA in both patients with AMD and those without vitreoretinal disease, while prolonged implicit time is associated with poorer visual outcome in those with AMD. Reduced a-wave amplitude and prolonged a-wave implicit time may therefore indicate a worse visual prognosis in patients listed for cataract surgery.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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