Abstract
Purpose::
To study the relationship between the best-corrected visual acuity (BCVA) and the amplitude and implicit time of the focal macular electroretinograms (FMERGs) in eyes with age-related macular degeneration (AMD).
Methods::
FMERGs were recorded from 139 eyes of 127 patients with untreated AMD (91 men, 36 women; age, 71.5± 8.43 years) under direct fundus observation using a modified infrared fundus camera and a 15 degrees stimulus. The eyes were classified into three groups according to their BCVA: Group A, BCVA <0.1, n=37; Group B, BCVA = 0.1-0.4, n=78; and Group C, BCVA ≥0.4, n=24. FMERGs were also recorded from 20 age-matched normal controls.
Results::
The amplitudes of FMERGs were significantly smaller (P<0.001), and the implicit times were significantly delayed (P<0.001) in all three AMD groups. There was a weak correlation between BCVA and the amplitude of the a-wave and b-wave of the FMERGs (a-wave, r=0.288, P=0.0006; b-wave, r=0.316, P=0.0001). The amplitude of the a-wave was significantly smaller in Group A than in Groups B and C (P<0.05). The implicit times of both the a- and b-waves were significantly longer in Group A than in Groups B and C.
Conclusions::
These results suggest that AMD eyes with lower visual acuity tend to have lower a-wave amplitudes and longer implicit times of the FMERG.
Keywords: age-related macular degeneration • electroretinography: clinical • visual acuity