The multifocal electroretinogram in aging and age-related macular degeneration

Age-related macular degeneration (AMD) is a common retinal disease that often causes a devastating loss of central vision. A good treatment for AMD has yet to be found. A reasonable course of action would be to treat the early form of the disease, age-related maculopathy (ARM), to prevent the development of AMD. ARM is much more prevalent than AMD, but only a small percentage of ARM patients convert to AMD. It would be beneficial to identify those ARM patients at the highest risk for conversion to AMD and direct treatment towards them. The electrophysiological and psychophysical studies of retinal function reported in this dissertation were motivated by this need.;The multifocal electroretinogram (MERG) is a new electrophysiological technique design to evaluate local retinal function. The first set of experiments (Chapter 3) demonstrated that the MERG technique shows little variability and is repeatable over a broad range of ages and average responses. An age-related change in MERG responses was found indicating that MERG studies of retinal disease need to employ age-matched controls.;The hypothesis that the MERG is sensitive to the retinal changes in AMD and ARM was tested in Chapter 4. Abnormal MERG responses (>2 SD from normal) were found in all of the AMD patients corresponding to the gross retinal abnormalities. MERG responses were also abnormal in 89% of the ARM patients. The degree of MERG abnormality was significantly related to the location and severity of soft drusen. Visual fields in the ARM patients were not different from the controls.;The usefulness of the rod MERG in ARM patients was tested in Chapter 5. Technical complexities limit the clinical applicability of rod MERG recordings.;The results in Chapter 6 showed that SKILL card low-luminance contrast sensitivity was significantly reduced in the ARM patient group, but individually, few ARM patients had abnormal results. Color vision testing with the D-15 test was not sensitive to the retinal changes in ARM patients.;In conclusion, the MERG is a simple, objective, sensitive, and non-invasive method to study retinal function in ARM. Longitudinal follow-up is required to identify high-risk ARM patients.