Is There a Blood-Brain Barrier at the Optic Nerve Head?

Mark O.M. Tso, Chi Yen Shih, Ian W. McLean

Research output: Contribution to journalArticlepeer-review

110 Scopus citations


The retina and optic nerve have been demonstrated to possess a blood-brain barrier that prevents the passive passage of protein and certain dyes from the blood vessels into the extracellular space. Our observations suggest that an exception is present at the normal optic disc. Using horseradish peroxidase as a tracer for electron microscopy and the normal rhesus monkey as the experimental animal, we have demonstrated that in certain regions of the optic nerve head, horse-radish peroxidase from the blood stream reaches the axons of the optic nerve through the border tissue of Elschnig from the adjacent choroidal tissues. A barrier formed by a series of cell junctions between glial cells at the edge of the optic disc prevented spread of the tracer from the optic disc into the subretinal space.

Original languageEnglish (US)
Pages (from-to)815-825
Number of pages11
JournalArchives of ophthalmology
Issue number9
StatePublished - Sep 1975
Externally publishedYes


  • Blood-brain barrier
  • horseradish peroxidase
  • optic nerve head

ASJC Scopus subject areas

  • Ophthalmology


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