Lornoxicam not only normalized the expression of cyclooxygenases in both models of PVR, but also neutralized the changes of the retina and the choroid thickness caused by the injection of pro-inflammatory agents.PVR is graded as Grade A, B, or C by the Silicone Oil Study and as Grade A, B, C, or D by the Retina Society Terminology Committee. Grade A is characterized by the appearance of vitreous haze and RPE cells in the vitreous. Grade B is characterized by wrinkling of the edges of the retinal tear or the inner retinal surface. Grade C is characterized by the presence of retinal membranes. Retinal membranes
The RPE cells migrate out into the vitreous, proliferate excessively and lay down ECM on both side sides of the detached retina. The ECM laid on the vitreous side of the retina are referred to as epiretinal or preretinal membranes (ERM) and those laid down between the RPE layer and the photoreceptors are referred to as subretinal or retroretinal membranes (SRM) . The two membranes differ in composition in that the ERM is composed of RPE cells, glial cells, macrophages and fibrocytes, while the SRM is rich in RPE cells. The subretinal membranes are of two types. One forms as diffuse sheets, which are not contractile and either lack or contain very little ECM. The presence of this type of membrane does not usually affect retinal reattachment surgery. The retina can be reattached even with the membrane in place.
The diagnosis is established by sequencing the TYROBP and TREM2 genes. Differential diagnosis
Frontotemporal dementia

Investigations
X rays show the presence of bone cysts and osteoporosis. CT or MRI of the brain show loss of tissue in the frontotemporal lobes of the brain. Calcification of the basal ganglia is common. EEG is typically normal initially but diffuse slowing and irritative activity later. Treatment
There is no specific treatment for this condition. Management is supportive. Epidemiology
This condition is considered to be rare, with ~200 cases described in the literature. The estimated population prevalence is 2.0 x 10−6 in Finns. History
This condition was first described in 1973. == References ==