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Definition

• Heterogeneous group of rare, genetic retinal diseases with congenital, non-progressive (stationary) visual impairments in twilight or darkness (night blindness)

Classification

• With normal fundus (classification according to full-field ERG
  • Schubert-Bornstein Type (X-linked/AR)
    • Complete subtype (cCSNB)
    • Incomplete subtype (iCSNB)
  • Riggs Type (AD)
• With fundus changes
  • Fundus albipunctatus ²
  • Oguchi disease

Schubert-Bornstein Type complete subtype (cCSNB)

• Symptoms: night blindness, reduced vision (about 0.5)
• Moderate to high myopia
• Nystagmus
• Small minority with color vision disorders
• Often strabismus
• Normal fundus (± myopic changes)
• ERG ¹ : pathological scotopic response / dark adaptation, no rod response
  • DA 0.01 missing, DA 10.0 electronegative (a-wave > b-wave)
  • Photopic response usually pathological
  • mfERG abnormal

Schubert-Bornstein Type incomplete subtype (iCSNB)

• Symptoms: night blindness (only about 50% of patients notice it), reduced vision (about 0.32), photophobia, and daytime visual complaints
• Myopia or hyperopia
• Sometimes nystagmus and/or strabismus
• Normal fundus (± myopic changes)
• ERG ¹ :pathological scotopic response / dark adaptation, partial rod response
  • DA 0.01 abnormal, DA 10.0 electronegative (a-wave > b-wave)
  • Photopic response significantly pathological
  • mfERG abnormal

Riggs Type

• Symptoms: night blindness with otherwise normal visual function
• Normal fundus
• ERG: ¹ : missing scotopic response, photopic response typically normal, mfERG normal

Fundus albipunctatus

• Night blindness/asymptomatic, typically normal vision and visual field
• Fundus ² : multiple small white dots, primarily mid-peripheral, macula mostly unaffected
• OCT ² : hyperreflective deposits in the retinal pigment epithelium extending into the outer nuclear layer (ONL)
• ERG ¹ : Abnormal scotopic response, variable photopic response
  • Improvement of scotopic response after prolonged dark adaptation
  • mfERG variable

Oguchi Disease

• Mizuo-Nakamura phenomenon : fundus with golden color during light adaptation, normalisation through dark adaptation
• ERG ¹ :
  • DA 0.01 missing, DA 10.0 electronegative (a-wave > b-wave)
  • Photopic response normal
  • Improvement of scotopic response after several hours of dark adaptation
  • mfERG normal

Work-up

• Dilated fundus examination
• Full-field ERG
• Genetic evaluation
• +/- autofluorescence and OCT

Differential Diagnoses

• Progressive rod-cone/cone-rod dystrophies
• Acquired causes of night blindness such as Vitamin A deficiency
• Melanoma-associated retinopathy (MAR)
• Retinitis punctata albescens

Treatment

• Currently none available

Sources

• EyeWiki – Congenital Stationary Night Blindness (CSNB)
• EyeWiki – Electroretinogram
• Ryan’s Retina; Charles P. Wilkinson, David R. Hinton, SriniVas R. Sadda, Peter Wiedemann; Elsevier – Health Sciences Division, 6th edition (2017)
• ¹ adaptiert von: Robson, A.G., Nilsson, J., Li, S. et al. ISCEV guide to visual electrodiagnostic procedures. Doc Ophthalmol 136, 1–26 (2018). https://doi.org/10.1007/s10633-017-9621-y
• ² von retinagallery.com, Contributor: Steven M Cohen

• Sergouniotis, P., Davidson, A., Sehmi, K. et al. Mizuo-Nakamura phenomenon in Oguchi disease due to a homozygous nonsense mutation in the SAG gene. Eye 25, 1098–1101 (2011). https://doi.org/10.1038/eye.2011.88