History of present illness
A 26-year-old man with severe obesity and mild intellectual impairment presents with gradually progressive, severe vision loss of both eyes. He denies floaters, ocular pain, flashes, and other ocular symptoms.
Ocular examination findings
Visual acuity was hand motion (HM) in both eyes with no improvement with pinhole. Pupils were equal in size and reactive to light without an afferent pupillary defect. Intraocular pressure was 16 mm Hg in both eyes. Anterior segment examination demonstrated 1+ posterior subcapsular cataracts of both eyes but was otherwise unremarkable. Dilated fundus examination of both eyes showed waxy optic nerve pallor with diffuse midperipheral pigmentary degeneration with mottling and scattered bone spicules. The vessels appeared to be mildly attenuated ( Figs. 3.1 and 3.2 ).
Questions to ask
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Does the patient have a family history of retinal disorders/dystrophies? Several retinal dystrophies such as retinitis pigmentosa have inheritance patterns and may lead to advanced vision loss at a young age.
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Not known
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Does the patient have postaxial polydactyly?
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Yes. The patient was born with extra digits and underwent surgery in early childhood ( Fig. 3.3 ).
Fig. 3.3
Birth certificate of the patient demonstrating polydactyly of the right and left foot.
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What medications does the patient take? Medications such as phenothiazines may concentrate in the retinal pigment epithelium and in some cases may manifest as a pigmentary retinopathy.
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None
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Does the patient have associated hearing loss? Hearing loss is a highly prevalent symptom in similar conditions such as Alström syndrome or Usher syndrome, whereas hearing loss is not as common in Bardet-Biedl syndrome (BBS).
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No
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Does the patient have a history of diabetes? Although obesity is a cardinal feature of BBS, diabetes is not common. Diabetes insipidus generally is more common with Alström syndrome.
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No
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Assessment
This is a case of a 26-year-old man reporting with severe, chronic vision loss in the context of retinal dystrophy with associated obesity, intellectual impairment, polydactyly, and unknown family history.
Differential diagnosis
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BBS
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Laurence-Moon syndrome
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Retinitis pigmentosa
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Usher syndrome
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Alström syndrome
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Joubert syndrome
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Leber congenital amaurosis
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Senior-Loken syndrome
Working diagnosis
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BBS
BBS is a clinical diagnosis. Diagnosis is confirmed in patients that meet at least four primary features ( Fig. 3.4 ) or three primary and two secondary features of BBS.
