The ocular phenotype of the Bardet-Biedl syndrome. Comparison to non-syndromic retinitis pigmentosa.

PURPOSE: To investigate 20 patients affected with Bardet-Biedl (BB) syndrome and compare them to an age-matched group of 70 non-syndromic patients with retinitis pigmentosa (RP) to identify hallmarks peculiar to the BB phenotype.

METHODS

Patients were examined clinically and with functional tests (color vision, kinetic perimetry, electroretinography, ocular motility tests). Fundus findings were numerically graded for statistical purposes.

RESULTS

Recurrent ocular features in BB patients were early and severe reduction of visual acuity, constantly altered color vision, high incidence of strabismus and nystagmus, mild-to-severe atrophic changes of the optic disc, and frequently absent or minimal pigmentary retinal changes. Visual acuity was more closely correlated to optic disc than to macular conditions. These findings were remarkably different from non-syndromic RP.

CONCLUSIONS

This investigation further suggests that retinopathy in BB syndrome has features distinctive from those in non-syndromic RP. The early occurrence of optic disc atrophy in the BB syndrome, even in those patients with healthy maculas, suggests that optic atrophy could often be primary in nature and might play a major role in decreasing central vision in BB patients. Variability of some findings is in line with the documented heterogeneity of the BB syndrome.