Abstract
Purpose: :
To evaluate the rod–mediated function in relatively early age–related macular degeneration (AMD).
Patients and Methods: :
Process of dark adaptation of thirteen patients (mean age 68.3 years) with early AMD as defined by drusen and focal hyperpigmentation but no geographic atrophy and ten age–matched normal adults were recorded using both new–devised dark adaptometer and ERG b–wave. Informed consent was given by all subjects after the nature and purpose of the study were explained.
Methods: :
Dark adaptation function was measured using goggle type dark adaptometer and measure the following index; rod–cone break; second components of rod–mediated dark adaptation; time to baseline sensitivity; baseline scotopic sensitivity. The ERG b–wave was recorded using Primus (Mayo, Aichi, Japan) during the process of dark adaptation and analyzed as an index of dark adaptation and measured the time to reach maximal amplitude of ERG b–wave.
Results: :
Although their visual acuity was at fairy good, patients with AMD exhibited deficits all rod–mediated parameters of dark adaptation compared to normals. The rod–cone break was delayed approximately 5 minutes in early AMD eyes. The time to reach maximal amplitude of ERG b–wave during dark adaptation were prolonged in AMD eyes (23.1±3.4 min) compared to normals (17.4±2.2 min).
Conclusions: :
Rod–mediated function during dark adaptation, which could be a sign of the recovery of the visual cycle in dark are disrupted in relatively early AMD eyes. The results both from the adaptmetry and ERG b–waves during dark adapation demonstrated a disrupted function in the AMD eyes. Evaluation of rod–mediated function was sensitive method for identifying the changes in AMD.
Keywords: age-related macular degeneration • electrophysiology: clinical • electroretinography: clinical