Purpose: To evaluate rod and cone function in individuals with the Laurence-Moon-Bardet-Biedl syndrome.
Methods: We obtained a full-field electroretinograms in 36 patients. If responses less than 10 microV were recorded with single white flashes a special techniques with narrow band filter and computer averaging was used.
Results: No rod responses to dim blue light could be obtained in any of the patients. Residual cone flicker responses were measurable in 28 of the individuals. Those with amplitudes < 0.05 microV were significantly older than those with amplitudes > 1.00 microV. The ERG pattern was consistent within affected pairs of siblings in 8 families.
Conclusion: The retinal dystrophy in Laurence-Moon-Bardet-Biedl syndrome is primarily a rod-cone dystrophy, but even cone flicker amplitudes are severely reduced with further progression with age. There is no intrafamilial variability of the electroretinograms in affected siblings.