optometry.naija: Glaucoma Week Series 2011- episode 4 ( The Trabecu...: "Optom To fully understand the pathophysiology of glaucoma, it becomes imparative to understand route of inflow as well as outflow of the aqu..."
Optom
optometry is discussed here, eye diseases and disabilities are highlighted and management of such ocular conditions enumerated.
Monday, 28 March 2011
Glaucoma Week Series 2011- episode 4 ( The Trabecular meshwork, the canal of Schlem and the Uveoscleral spaces)
Optom
To fully understand the pathophysiology of glaucoma, it becomes imparative to understand route of inflow as well as outflow of the aqueous humor. It should be remembered that the eye is considered a leaking system of aqueous humor.
The trabecular meshwork is divided into three, they include the following-
1) The inner uveal meshwork: This part is closest to the anterior chamber. It is radially oriented and contains trabeculae.
2) The corneoscleral meshwork: This part consists oflarge amount of elastin and often described as the ciliary muscle tendon.
3) The Juxtacanacular meshwork (Cribiform meshwork): This part is close to the canal of Schlem (Sinus Venosus Sclerae). It consists of a thin strip of tissue covered by mono-layer endothelial cell. It recieves support by the connective tissues ground substances full of glycoaminoglycans and glycoproteins.
The canal of Schlem is acircular canal lined with endothelium that runs around the eyeball at the corneoscleral junction. It is positioned within the internal scleral sulcus and posteriorly related to the scleral spur. The inner endothelial wall of the sinus is related to the trabecular meshwork and the anterior chamber; but there is no direct passage way between the trabecular meshwork, the anterior chamber cavity and the sinus.
The scleral sinus is drained by 25-30 collector canals via the deep scleral venous plexus, then into the intrascleral plexus & the episcleral plexus which enters the larger circulation via the anterior ciliary veins.
A few of the collector canals bypass the deep scleral venous plexus and pass directly into the sclera via the subchoroidal vessels. These collector channels are known as aqueous veins.
85-95 % of aqueous outflow takes place through the trabecular meshwork via the Sinus Venosus Sclerae.
To be continued...
Dr Ezebuiroh Victor Okwudiri
To fully understand the pathophysiology of glaucoma, it becomes imparative to understand route of inflow as well as outflow of the aqueous humor. It should be remembered that the eye is considered a leaking system of aqueous humor.
The Trabecular Meshwork
The trabecular meshwork is a spongy porous tissue lined with trabeculocytes. It is located around the base of the cornea just beyond the line of Schwalbe. It sits just above the anterior fenestrated iris. It runs the course of the entire corneal base of the eye. It is avascular.The trabecular meshwork is divided into three, they include the following-
1) The inner uveal meshwork: This part is closest to the anterior chamber. It is radially oriented and contains trabeculae.
2) The corneoscleral meshwork: This part consists oflarge amount of elastin and often described as the ciliary muscle tendon.
3) The Juxtacanacular meshwork (Cribiform meshwork): This part is close to the canal of Schlem (Sinus Venosus Sclerae). It consists of a thin strip of tissue covered by mono-layer endothelial cell. It recieves support by the connective tissues ground substances full of glycoaminoglycans and glycoproteins.
Canal Of Schlem (Sinus Venosus Sclerae)
The canal of Schlem is acircular canal lined with endothelium that runs around the eyeball at the corneoscleral junction. It is positioned within the internal scleral sulcus and posteriorly related to the scleral spur. The inner endothelial wall of the sinus is related to the trabecular meshwork and the anterior chamber; but there is no direct passage way between the trabecular meshwork, the anterior chamber cavity and the sinus.
The scleral sinus is drained by 25-30 collector canals via the deep scleral venous plexus, then into the intrascleral plexus & the episcleral plexus which enters the larger circulation via the anterior ciliary veins.
A few of the collector canals bypass the deep scleral venous plexus and pass directly into the sclera via the subchoroidal vessels. These collector channels are known as aqueous veins.
85-95 % of aqueous outflow takes place through the trabecular meshwork via the Sinus Venosus Sclerae.
The Uveoscleral pathway
The junction between the uveal portion of the eye and the sclera is linked by the ciliary body smooth muscles. This area has been noted to play a role in outflow of aqueous humor. This area provides about 5-15 % drainage of the aqueous humor. It is known as the 'Extracanalicular' pathway. The aqueous humor is drained into the orbital blood vessels. Recently, the uveoscleral pathway has assumed a very important mechanism in the outflow mechanism of the aqueous humor.To be continued...
Dr Ezebuiroh Victor Okwudiri
Sunday, 27 March 2011
optometry.naija: Glaucoma Week Series 2011- episode 3 (The anatomy ...
optometry.naija: Glaucoma Week Series 2011- episode 3 (The anatomy ...: "Optom The Ciliary Body is a complete ring tissue that runs around the inside of the anterior sclera. It measures about 6 mm wide ( sli..."
Optom
Optom
Glaucoma Week Series 2011- episode 3 (The anatomy of the ciliary body)
Optom
The Ciliary Body is a complete ring tissue that runs around the inside of the anterior sclera. It measures about 6 mm wide ( slightly wider temporally than nasally). Anteriorly, the ciliary body extends to the sleral spur (This acts as an attacchment for the ciliary body ventrally. On the posterior side, the ciliary body continues into the ora serrata of the retina.
The ciliary body is divided into the anterior 'pars plicata' which is ridged and give rise to the ciliary process on which the crystalline lens zonule suspensory ligament anastomose. And the posterior 'pars plana' is smooth and flat which extends into the ora serrata and the choroid. @ the margin between the ora serrata and the ciliary body, the 'pars plana' is modified into a scalloped edge that fits into and corresponds with the tooth-like edge of the ora serrata of the neural part of the retina.
Structurally speaking, the ciliary body is made up of (1) The ciliary epithelium, (2) The ciliary stroma, and (3) The ciliary muscle.
The ciliary epithelium is that outermost part of the ciliary body that cover the inner surface of the cilliary body. It is made of two layers of pigmented and non-pigmented epithelial cells with their apices juxtaposing. Their basement membrances lies paralel with each other. These arrengement is unique and unlike in other epithelial cell which justifies the diferences in the content of blood plasma and aqueous humor! The ciliary epithelium forms the blood-aqueous barrier which plays a significant role in Intra-ocular pressure (IOP) maintainance.
The ciliary stroma is a bundle of loose connective tissue, rich in blood vessels and melanocytes. The loose connective tissue in the stroma forms a connective tissue core with the ciliary process. The stroma also provides attachment for the ciliary muscles which functions in crystaline lens accomodation.
The ciliary muscle is innervated by the posganglionic parasympathetic fibres derived from the oculo-motor nerves, via the short cilliary nerves. They form the bulk of the ciliary body and consists of smooth muscle fibres.
Finally,the aim of this detailed discription of the ciliary body is to identify the role it plays in production of aqueous humor and the regulation of IOP in the eye. The eye is regarded as a leaking system for aqueous humor, from the ciliary body to the collector channels and aqueous veins of the Sinus venosus sclerae (canal of Schlem); or the episcleral spaces. It is on record that the rate of aqueous humor formation is approximately 2.4+/-0.6 ul/min (Micro-liter per minute).
To be continued...
Dr Ezebuiroh Okwudiri Victor.
The Ciliary Body is a complete ring tissue that runs around the inside of the anterior sclera. It measures about 6 mm wide ( slightly wider temporally than nasally). Anteriorly, the ciliary body extends to the sleral spur (This acts as an attacchment for the ciliary body ventrally. On the posterior side, the ciliary body continues into the ora serrata of the retina.
The ciliary body is divided into the anterior 'pars plicata' which is ridged and give rise to the ciliary process on which the crystalline lens zonule suspensory ligament anastomose. And the posterior 'pars plana' is smooth and flat which extends into the ora serrata and the choroid. @ the margin between the ora serrata and the ciliary body, the 'pars plana' is modified into a scalloped edge that fits into and corresponds with the tooth-like edge of the ora serrata of the neural part of the retina.
Structurally speaking, the ciliary body is made up of (1) The ciliary epithelium, (2) The ciliary stroma, and (3) The ciliary muscle.
The ciliary epithelium is that outermost part of the ciliary body that cover the inner surface of the cilliary body. It is made of two layers of pigmented and non-pigmented epithelial cells with their apices juxtaposing. Their basement membrances lies paralel with each other. These arrengement is unique and unlike in other epithelial cell which justifies the diferences in the content of blood plasma and aqueous humor! The ciliary epithelium forms the blood-aqueous barrier which plays a significant role in Intra-ocular pressure (IOP) maintainance.
The ciliary stroma is a bundle of loose connective tissue, rich in blood vessels and melanocytes. The loose connective tissue in the stroma forms a connective tissue core with the ciliary process. The stroma also provides attachment for the ciliary muscles which functions in crystaline lens accomodation.
The ciliary muscle is innervated by the posganglionic parasympathetic fibres derived from the oculo-motor nerves, via the short cilliary nerves. They form the bulk of the ciliary body and consists of smooth muscle fibres.
Finally,the aim of this detailed discription of the ciliary body is to identify the role it plays in production of aqueous humor and the regulation of IOP in the eye. The eye is regarded as a leaking system for aqueous humor, from the ciliary body to the collector channels and aqueous veins of the Sinus venosus sclerae (canal of Schlem); or the episcleral spaces. It is on record that the rate of aqueous humor formation is approximately 2.4+/-0.6 ul/min (Micro-liter per minute).
To be continued...
Dr Ezebuiroh Okwudiri Victor.
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