Vitreo-retinal disease

• Attachments between vitreous and retina


  Vitreous base > posterior lens > optic disc > macula > retinal vessels
• Components of the vitreous humour

  • Water
  • Collagen
  • Hyaluronan
  • Other small molecules
• Vitreous humour

  A transparent gel-like structure primarily formed of water (98%), collagen (gel base), hyaluronan (viscosity), and a combination of other small molecules. It is viscoelastic, providing structural support and acting as a shock-absorber
• The blurred circular back region ('Mittendorf’s spot' or 'dot') is the opaque remnant of the anterior hyaloid artery. Rarely, the entire hyaloid artery can remain after birth, leaving a persistent hyaloid artery (aka 'Bergmeister's papilla')
• During embryological development, the hyaloid artery connects the blood supply of the optic nerve head with the anterior eye. The supporting channel remains and fills with clear fluid, forming Cloquet’s canal or the hyaloid canal
• All of this document’s material is part of the module’s syllabus and is therefore examinable
• The document should be read in combination with your learning material on ocular anatomy from previous modules, especially OHA1 or Optometric Skills
• Retina anatomy

  The inner limiting membrane lies at the top of the diagram, closest to the vitreous. The strongest attachment between the vitreous and retina is at the vitreous base, which is a ring-shaped attachment extending around the ora serrata
• The aim of this document is to provide a description of vitreous pathology and retinal detachments from the perspective of an Optometrist
• Vitreous anatomy

  The vitreous core is enveloped by a thin shell referred to as the ‘vitreous cortex’ or ‘hyaloid membrane’. The vitreous base is located anteriorly and is the site of firm attachments between the anterior hyaloid membrane of the vitreous and the ora serrata
• Mittendorf's dot is unlikely to give rise to symptoms but visual acuity can be reduced if the opaque region is large enough and close enough to the visual axis
• Persistent hyaloid artery may give rise to symptoms of floaters and/or reduced visual acuity
• Common remnants of the hyaloid artery

  • Small fragments attached to the posterior surface of the lens after development
• Conditions that maximise the visibility of floaters are likely to lead to patients becoming more symptomatic
• Bergmeister's papilla


  An opaque or semi-opaque strand extending from the optic nerve head to the anterior hyaloid membrane
• The hyaloid artery can remain after birth leaving a persistent hyaloid artery (aka 'Bergmeister's papilla')
• Young adults, particularly if myopic, may report symptoms of floaters due to vitreous degeneration
• Vitreous synchysis and syneresis may become manifest in patients of any age, with age-related changes accelerated in myopic eyes
• Posterior vitreous detachment (PVD) is a separation of the vitreous from the sensory retina, occurring posterior to the vitreous base
• In PVD, the posterior hyaloid membrane detaches from the retina, while the attachment between the anterior hyaloid membrane and the ora serrata typically remains intact
• Mittendorf's spot or dot


  A small, approximately circular opacity formed by small fragments of the hyaloid artery attached to the posterior surface of the lens
• Vitreous Degeneration

  1. Ageing is associated with a liquefaction of the vitreous, termed vitreous synchysis, where the vitreous becomes more fluid and less of a gel

  2. Vitreous syneresis leads to the liberation of small collagen fibrils from the vitreous structure, which then aggregate to form floaters that cast shadows on the retina
• Vitreous degeneration is significantly accelerated in myopic eyes
• Development of a perforation in the lining of the vitreous cortex

  Allows fluid (the product of synchysis - liquefaction) to leak into the space between the anterior layer of the retina (inner limiting membrane) and the posterior vitreous: the retrovitreous space. This influx of fluid enlarges the retrovitreous space and catalyses the detachment of vitreous from retina.
• A PVD occurs slowly, over the course of several months
• PVDs often start in the macular region
• The detachment of the vitreous from the optic nerve head indicates that the PVD is advanced
• Although the Posterior vitreous detachment is advanced, the entire vitreous is not fully detached; a strong attachment persists at the vitreous base between the anterior vitreous and the ora serrata
• Partial detachments occur when attachments between the vitreous and retina remain intact elsewhere
• Dr J Heron: 'The underlying cause of a PVD is the preceding vitreous degeneration: synchysis (liquefaction) and syneresis (shrinkage). This degeneration places tension upon the weak attachments between the posterior vitreous (specifically the posterior hyaloid membrane/posterior vitreous cortex) and the retina: the vitreo-retinal interface. These attachments are strong in youth but weaken progressively with age. This weakening leads to ‘vitreo-retinal dehiscence’: separation of vitreous from retina. This separation allows the vitreous to collapse centripetally (inwards toward the centre of the globe) under the forces created by the synchysis and syneresis described above.'
• Myopic patients are at risk of developing a PVD significantly earlier than emmetropes or hypermetropes
• Residual adherence between vitreous and retina can lead to vitreo-retinal traction, retinal tears, macular holes/puckers, and epiretinal membranes
• Prevalence of PVD: 8% in 40-50 year olds, 44% in 60-67 year olds, and 86% in 80-90 year olds
• The Weiss ring is a circular, translucent floater visible during fundoscopy by focusing the slit lamp in the posterior vitreous, within the region of the optic nerve head
• Ocular trauma, such as cataract extraction surgery, increases the risk of PVD
• The Weiss ring indicates that the PVD is advanced as the attachment between the vitreous and retina at the optic nerve head is significantly stronger than elsewhere in the posterior eye
• Females are approximately 2-3 times more likely to develop a PVD than males
• Age is a powerful risk factor for the development of PVD
• The Weiss ring may be reported by the patient as a symptom, appearing as a large, approximately circular floater in central vision
• A PVD is painless and classically associated with...