Abstract
Purpose::
To study the functional changes in the macula area of the retina in the early stage of retinitis pigmentosa (RP) by analyzing each component of the focal macular electroretinogram (FMERG).
Methods::
FMERGs were recorded from 39 RP patients with normal visual acuity (>1.0) under direct fundus observation using a modified infrared fundus camera and 5, 10, and 15 degrees stimulus spots. The amplitudes and implicit times of the a-wave, b-wave, and oscillatory potentials (OPs) from the RP patients were compared to those from 30 age-matched normal controls.
Results::
The amplitudes of the different components of the FMERGs in RP patients ranged from severe reduction to normal. The degree of amplitude reduction increased as the size of the stimulus spot increased in the RP patients. The relative amplitudes of the OPs (67% of the mean of normals) were better preserved than that of the b-wave (46%) and the a-wave (39%) for a 10° spot in the RP patients.
Conclusions::
These results suggest that the neural activities from the inner retina are better preserved than those from the intermediate and outer retina in the central retina at the early stage RP. Recordings of each component of FMERG can provide important information on the different layers of the central retina in eyes with RP and to the understanding of the pathophysiology of RP.
Keywords: degenerations/dystrophies • electroretinography: clinical • retina