History of present illness
The patient is a 46-year-old practicing neurologist reporting difficulty with near vision. His fundus examination is abnormal, and upon questioning he says he has been told in the past that he has “some type of retinal condition” but no further evaluation was ever done. He says that as a youngster, he was never good at playing Ghosts in the Graveyard.
Ocular examination findings
Visual acuity with correction was 20/25 right eye and 20/20 left eye. Pupils were 4 mm and equally reactive. Motility was full. Visual fields were full but slow to confrontation. There were macular white flecks in each eye. The peripheral retina showed midperipheral rings of pigment atrophy and nummular pigment migration into the retina ( Fig. 10.1 ). Goldmann fields demonstrated a midperipheral scotoma in the right eye. External and anterior segment examinations were normal, and intraocular pressures were 16 mm Hg in each eye.
Imaging
Fluorescein angiography showed areas of hyperfluorescence in the midperiphery consistent with areas of pigment atrophy ( Fig. 10.2 ). In the optical coherence tomography (OCT) images, the maculas were fairly normal, but the periphery of each retina showed extensive disruption of the outer layers ( Fig. 10.3 ).
Questions to ask
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Is the patient on any medications?
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No
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Do any other family members have ocular reports of night blindness or hereditary eye conditions?
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No
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Assessment
A 46-year-old physician presented with good distance vision, a chief complaint of presbyopia, and, when asked, mild night blindness. Peripheral retinal atrophy and pigmentation is present in the fundus.
Differential diagnosis
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Retinitis pigmentosa (RP)
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Medication toxicity, such as thioridazine retinopathy
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Enhanced S-cone syndrome
Working diagnosis
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Enhanced S-cone syndrome
Genetic testing
Genetic analysis at the Carver Nonprofit Genetic Testing Laboratory at the University of Iowa showed a missense mutation (Arg311Gln) and a splice site mutation (IVS1–2A>C) in the NR2E3 genes, consistent with a diagnosis of autosomal recessive enhanced S-cone syndrome.
Multimodal testing and results
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Fundus photographs: Midperipheral symmetrical atrophy with nummular (not bone spicule–like) pigment migrations is seen. Flecks are present in the macular regions with sparing of the periphery in enhanced S-cone syndrome in contrast to retinitis pigmentosa, which shows peripheral bone spicule-like pigment changes.
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Fluorescein angiography: Hypofluorescence consistent with areas of pigment atrophy in the periphery are seen.
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OCT: Demonstrates sparing of the maculas with extensive outer retinal damage pericentrally and in the periphery.
Diagnosis
Molecular genetic analysis is available and necessary to confirm the correct diagnosis.
Enhanced S-cone syndrome
This condition, previously known as Goldmann-Favre syndrome, was identified in the 1990s and contains mutations in the NR2E3 gene, which is a transcription factor important in embryonic development. These patients have 17 times more blue cones (S or “small wavelength” cones) than red (L or “large wavelength”) or green (M or “medium wavelength”) cones and few rods. Some patients develop schisis cavities in the periphery. The combination of retinoschisis and pigmentary retinopathy was previously known as Goldmann-Favre Syndrome until recent advances in the genetic identification.
Management
No medical treatment is available, and though there is slow progression, there is considerable variability in the prognosis, with some patients, such as this patient, maintaining excellent central acuity and mild field loss.
Follow-up care
The patient was prescribed reading glasses and will be seen annually for examination.
Algorithm 10.1 : Algorithm showing diagnosis for enhanced s-cone syndrome
