Changes

====Aqueous Humour====

====Aqueous Humour====

Aqueous humour is produced by '''ciliary processes''' of the '''ciliary body'''. It is a transparent ultra-filtrate of plasma.  Its continual flow is vital for the delivery of nutrients and removal of waste products to the avascular structures it bathes; lens, inner portion of the cornea (including corneal endothelium) and trabecular meshwork.  Once produced aqueous traverses the posterior chamber, passes through the pupil and enters the anterior chamber where it can then drain at the '''iridiocorneal angle'''. The aqueous is optically clear under normal conditions, a property important for vision. An opacity in the aqueous humour is usually the result of an inflammatory process. The '''blood-aqueous barrier''' to free diffusion of molecules is formed by the tight junction between non-pigmented epithelial cells of the ciliary body.  Breakdown of this barrier occurs in many conditions, including inflammation, trauma and vascular disease.  Interventions such as paracentesis and surgery also causes breakdown, as does topical administration of drugs such as pilocarpine.  Typically, the aqueous humour becomes turbid (aqueous flare) because of leakage of plasma proteins into the anterior and posterior chambers due to the damaged barrier and loss of vessel integrity.  Fibrinogen and other proteins render the aqueous ‘plasmoid’, as its protein content approaches that of plasma, and when inflammation is severe fibrin clots may form.  The cellular component varies according to the underlying aetiology.  A preponderance of white blood cells is termed '''hypopyon''' and a preponderance of red blood cells is called '''hyphaema'''.  It also maintains intraocular pressure (25mm.Hg), and is replaced several times a day (2µl/min). An increase in intraocular pressure can cause [[Glaucoma - Donkey|glaucoma]].

Aqueous humour is produced by '''ciliary processes''' of the '''ciliary body'''. It is a transparent ultra-filtrate of plasma.  Its continual flow is vital for the delivery of nutrients and removal of waste products to the avascular structures it bathes; lens, inner portion of the cornea (including corneal endothelium) and trabecular meshwork.  Once produced aqueous traverses the posterior chamber, passes through the pupil and enters the anterior chamber where it can then drain at the '''iridiocorneal angle'''. The aqueous is optically clear under normal conditions, a property important for vision. An opacity in the aqueous humour is usually the result of an inflammatory process. The '''blood-aqueous barrier''' to free diffusion of molecules is formed by the tight junction between non-pigmented epithelial cells of the ciliary body.  Breakdown of this barrier occurs in many conditions, including inflammation, trauma and vascular disease.  Interventions such as paracentesis and surgery also causes breakdown, as does topical administration of drugs such as pilocarpine.  Typically, the aqueous humour becomes turbid (aqueous flare) because of leakage of plasma proteins into the anterior and posterior chambers due to the damaged barrier and loss of vessel integrity.  Fibrinogen and other proteins render the aqueous ‘plasmoid’, as its protein content approaches that of plasma, and when inflammation is severe fibrin clots may form.  The cellular component varies according to the underlying aetiology.  A preponderance of white blood cells is termed '''hypopyon''' and a preponderance of red blood cells is called '''hyphaema'''.  It also maintains intraocular pressure. An increase in intraocular pressure can cause [[Glaucoma - Donkey|glaucoma]].

====Lens====

====Lens====

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All of the extraocular muscles originate at the equator of the eyeball.

All of the extraocular muscles originate at the equator of the eyeball.

===Clinical Links===

===Clinical Links===

*Click here for information on [[Vestibular System Examination]] in the horse.

*Click here for information on [[Vestibular System Examination]] in the horse.