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Date Posted: 22:32:34 11/11/07 Sun
Author: Vancomycin
Subject: Re: Retinal detachment
In reply to: ªA³¡¥bÂà 's message, "Retinal detachment" on 18:03:28 11/01/07 Thu

>Hello Dr.V ! It is me again :)
>
>I'm not sure about the pathology of retinal detachment
>in terms of biochemistry , the books just said it has
>something to do with hyaluronic acids with no
>explanation.
>
>Plz help me :)

Haha, this is truely an ophthalmological question... I haven't touched it since medical school days...

<a rel=nofollow target=_blank href="http://en.wikipedia.org/wiki/Retinal_detachment">http://en.wikipedia.org/wiki/Retinal_detachment</a>
<a rel=nofollow target=_blank href="http://www.emedicine.com/emerg/topic504.htm">http://www.emedicine.com/emerg/topic504.htm</a>

Pathophysiology: Retinal detachment refers to separation of the inner layers of the retina from the underlying retinal pigment epithelium (RPE, choroid). The choroid is a vascular membrane containing large branched pigment cells sandwiched between the retina and sclera. Separation of the sensory retina from the underlying RPE occurs by the following 3 basic mechanisms:

* A hole, tear, or break in the neuronal layer allowing fluid from the vitreous cavity to seep in between and separate sensory and RPE layers (ie, rhegmatogenous RD)

* Traction from inflammatory or vascular fibrous membranes on the surface of the retina, which tether to the vitreous

* Exudation of material into the subretinal space from retinal vessels such as in hypertension, central retinal venous occlusion, vasculitis, or papilledema

RDs may be associated with congenital malformations, metabolic disorders, trauma (including previous ocular surgery), vascular disease, choroidal tumors, high myopia or vitreous disease, or degeneration.

Of the 3 types of retinal detachment, rhegmatogenous RD is the most common, deriving its name from rhegma, meaning rent or break. Vitreous fluid enters the break and separates the sensory retina from the underlying RPE, resulting in detachment.

Exudative or serous detachments occur when subretinal fluid accumulates and causes detachment without any corresponding break in the retina. The etiologic factors are often tumor growth or inflammation.

Tractional retinal detachment occurs as a result of adhesions between the vitreous gel and the retina. Centripetal mechanical forces cause the separation of the retina from the RPE without a retinal break. Advanced adhesion may result in the development of a tear or break. The most common causes of tractional RD are proliferative diabetic retinopathy, sickle cell disease, advanced retinopathy of prematurity, and penetrating trauma. Vitreoretinal traction increases with age, as the vitreous gel shrinks and collapses over time, frequently causing posterior vitreous detachments in approximately two thirds of persons older than 70 years.

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