Stability of the eye

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The stability of the eye refers to the geometrical center of the eyeball being maintained in a fixed position throughout all eye movements. In other words, eye movements are always rotational about a fixed center. This degree of stability is achieved by several structures that form the 'supporting apparatus of the eye'.

​Gross anatomy

The following structures form the supporting apparatus of the eye:

  • the fascial sheath of the eye: envelops the eyeball like a socket, extending from the corneoscleral junction to the optic nerve. It is pierced by the tendons of the four recti and two obliques and is reflected over them as a tubular muscle sheath. 
  • ligaments:
    • ​lateral check ligament: the thickened tubular muscle sheath over the outer layer of the lateral rectus. It is attached to the marginal tubercle (of Whitnall) on the orbital surface of the zygomatic bone
    • medial check ligament: the thickened tubular muscle sheath over the outer layer of the medial rectus. It is attached to the posterior lacrimal crest at the same horizontal level as the marginal tubercle
    • suspensory ligament (of Lockwood): the thickened part of the fascial sheath of the eye posteriorly that extends between the medial and lateral check ligaments, which forms a sling, like a hammock, for the support of the eye. It suspends the eye above the floor of the orbit. It is therefore preserved during surgical removal of the bony floor of the orbit when resecting a tumor 
  • orbital fat: lies inside and outside the cone of muscles and forms a cushion which prevents posterior displacement of the eyeball. If its volume increases, it results in exophthalmos. If its volume decreases, it results in exophthalmos
  • oblique muscles: 

    • Both oblique muscles, due to their positioning, exert a forward pull of the eye which helps prevent posterior displacement of the eye.

    The attachments of the medial and lateral recti to the bony margins of the orbit via the check ligaments also help in preventing posterior displacement of the eye.