Multifocal electroretinographic responses in sector retinitis pigmentosa.

Headings: Multifocal electroretinography (mfERG) may be useful in the management of sector retinitis pigmentosa (SRP).
Aim: To compare multifocal electroretinographic responses in SRP, generalised retinitis pigmentosa (GRP), and healthy controls.
Methods: Eighteen patients with SRP, twelve with GRP, and fifteen controls were included in the study. All participants underwent: complete ophthalmological examination, Humphrey visual field testing, full-field ERG, and mfERG. The mean P1 amplitude, the implicit time (IT), and the mapping of the local responses were evaluated.
Results: The mean P1 amplitude was higher in the SRPs than in GRPs (p < 0.001), while it did not differ between SRPs and controls (p = 0.913). In the SRPs, the P1 amplitude in pathologic areas was higher than in the GRPs (p < 0.001). In normal areas, this parameter did not differ from the controls (p = 0.499). Moreover, in the SRPs, no differences in the P1 amplitude and the IT between pigmented and non-pigmented areas were found.
Conclusion: In the present study, the mfERG examination displayed significant differences between sector and generalised RP, showing normal values in sector RP even in pigmented areas. Considering the patients included in this study, SRP seems to represent a favourable variant of the disease, characterised by a limited retinal involvement and apparently mild functional damage. It is still unclear how these results can be extended to other forms of SRP.