Abstract
Purpose: :
To simulate multifocal double flash responses in normals and patients with retinal diseases using the mfERG.
Methods: :
We analyzed the data taken by means of the standard mfERG protocol in 73 normal subjects. Normally, only the first - order kernel from the mfERG is analyzed. We have developed a method of analysis we call "synthesis" which combines all kernels above the noise level. We can then synthesize or simulate what responses would look like if a stimulus consisted of a series of flashes. Our primary interest is with simulating a double flash experiment with increasing flash intervals. Recovery curves after adaptation to the initial test flash were plotted. The data recorded in patients with age related macular degeneration (AMD) and diabetic retinopathy (DM) were analyzed with the same technique and compared to the mean of the normals.
Results: :
The average time course of response recovery rate in normals was linear followed by saturation. Complete recovery to the isolated single flash response was reached after approximately 50 ms. In some AMD patients, highly abnormal recovery was seen in the center, while the recovery was within normal range in the periphery. A patient with DM showed little response recovery in the whole tested area, although his standard mfERG results presented in usual form did not show severe abnormality.
Conclusions: :
The kernel series derived from standard multifocal m-sequence records provides local information on the response kinematics. Patients whose first order response topography is within normal range may show highly abnormal response recovery after flash. The derivation of recovery curves from standard multifocal records may have clinical application.
Keywords: electroretinography: clinical • electroretinography: non-clinical • retina