Multifocal electroretinogram contributes to differentiation of various clinical pictures within a family with Bardet-Biedl syndrome

Abstract

Purpose: To demonstrate the use of the multifocal electroretinogram (mfERG) in addition to the full-field electroretinogram (ERG) in defining varying clinical pictures in children within a family with Bardet-Biedl syndrome (BBS).

Methods: All members from a family generation underwent a detailed history and examination before proceeding to a detailed ERG in accordance with the International Society of Clinical Electrophysiology for Vision protocol and a rapid, low-resolution mfERG. Of the sibling pair, the 13-year-old boy showed reduced vision and atypical maculopathy and the 10-year-old sister showed normal vision and atrophic maculopathy. Parents had normal ocular examination.

Results: The male sibling had reduced rod and cone full-field ERG responses with a relatively spared central response from the mfERG suggesting central macular sparing. In contrast, for the female sibling, the ERG was normal for the cone pathway although reduced for rod pathway, with mfERG showing central involvement. The mother had rod responses at the lower end of normal range, a normal cone pathway, and a normal mfERG. The father showed a normal ERG and mfERG.

Conclusion: The mfERG is a useful adjunct to full-field ERG in the paediatric population and in family studies.

Figure 1

(a) Fundus photographs of the male sibling showed attenuated vessels and atrophic maculopathy. (b) Fundus photographs of the female sibling showed signs of maculopathy with mild retinal vessel attenuation (OD: right eye, OS: left eye).

Figure 2

Full-field electroretinograms (ERGs) of the male sibling showed diminished responses of both rod and cone pathway with rod pathway more severely affected. RE, right eye; LE, left eye; DFD, dim flash in the dark; SFD, standard flash in the dark; SFL, standard flash in the light.

Figure 3

(a) Multifocal electroretinograms (mfERGs) of the male sibling showed central sparing. (b) Mf ERG of the female sibling suggested a subtle macular change with an attenuated central hexagon amplitude response.

Figure 4

Full-field electroretinograms (ERGs) of the female sibling showed normal cone responses, with rod pathway responses about 50% of the lower limit of normal for amplitude. RE, right eye; LE, left eye; DFD, dim flash in the dark; SFD, standard flash in the dark; SFL, standard flash in the light.

Figure 5

Multifocal electroretinograms (mfERGs) of the male sibling showed reduced central hexagon response from the LE compared with the RE (RE: right eye, LE: left eye).