Abstract
Purpose: :
The multifocal ERG (mfERG) has been shown to be reproducible in healthy subjects. A good reproducibility in healthy subjects is the basis for the application of the technique. In clinical routine, repeated mfERG measurements are often performed to exclude disease progression for which an estimate of reproducibility in patients is necessary. The aim of the present study is to determine the mfERG reproducibility in patients suffering from central retinal disease so that .
Methods: :
MfERG measurements were performed with a DTL electrode. The stimulus consisted of 61 hexagons. 5 healthy subjects and 5 patients with central retinal pathology (e.g. Stargardt) were examined twice, with a short break of several minutes in between. During this time, the electrode was left in place; its localisation was checked before each measurement.Differences of P1 amplitude and latency of the central hexagon , ring 1 and ring 2 between first and second measurement was determined by the paired sample T-Test.
Results: :
In healthy subjects, no differences between P1 amplitude and latency in the central hexagon, ring 1 and ring 2 were found. We were able to find a significant difference between 1st and 2nd measurement in P1 amplitude in ring 1 and P1 latency in ring 1 in the group of patients suffering from central retinal pathology. Mean P1 amplitude in ring 1 was 0.62 +- 0.25 µV in the 1st and 0.65 +- 0.27 µV in the 2nd measurement. Mean P1 latency in ring 1 was 44.8 +- 2.9 ms in the 1st and 44.1 +- 2.9 ms in the 2nd measurement. There was no significant difference between 1st and 2nd measurement in the central hexagon and ring 2.
Conclusions: :
Reproducibility of mfERG recordings is very good in healthy subjects but reduced in patients.. Reasons may be: unstable fixation due to reduced visual acuity, poor patient compliance or the pathology itself. The establishment of limits of reproducibility is fundamental to be able to determine the rate of disease progression.
Keywords: electroretinography: clinical