Steady-state pattern electroretinogram and frequency doubling technology in anisometropic amblyopia

Background: Steady-state pattern electroretinogram (PERG) and frequency doubling technology (FDT) perimetry can be used to selectively investigate the activity of the M-Y ganglion cells in adult anisometropic amblyopes. Methods: Fifteen normal subjects (mean 27.8±4.1 years) and 15 adults with anisometropic amblyopia (mean 28.7±5.9 years) were analyzed using steady-state PERG and FDT. Results: The amplitude of steady-state PERG was significantly different not only among the control group and both the amblyopic eye ( P =0.0001) and the sound eye group ( P =0.0001), but also between the latter two groups ( P =0.006). The difference in FDT mean deviation was statistically significant not only between the control group and amblyopic eye group ( P =0.0002), but also between the control group and the sound eye group ( P =0.0009). The FDT pattern standard deviation was significantly higher in the control group rather than in the amblyopic eye ( P =0.0001) or the sound eye group ( P =0.0001). A correlation was found between the reduction in PERG amplitude and the increase in FDT-pattern standard deviation index not only in amblyopic ( P =0.0025) and sound ( P =0.0023) eyes, but also in the healthy control group ( P =0.0001). Conclusion: These data demonstrate that in anisometropic amblyopia, there is an abnormal functionality of a subgroup of the magnocellular ganglion cells (M-Y), and the involvement of these cells, together with the parvocellular pathway, may play a key role in the clinical expression of the disease.