Therapeutic Effect Of Intravitreal Administration Of Indomethacin On Experimential Proliferative Vitreoretinopathy

Objective To investigate the therapeutic effect of intravitreal administration of indomethacin on experimential proliferative vitreoretinopathy (PVR), and also to study the toxicity of indomethacin on retina in the pigment rabbits. Methods Twenty pigment rabbits were divided randomly and evenly into four groups: high-dose group ,low-dose group .control group and toxicity experiment group. In the first three groups, rabbit eyes were intravitreal injected platelet-rich plasma to induce the experimential proliferative vitreoretinopathy. One day later, animals in high-dose group were intravitreal injected alcohol containing 7.5mg indomethacin, and in low-dose, 5mg indomathin. Alcohol was intravitreally administrated in the control- group. After injection, PVR changes were evaluated according to Fastenserg method on 7,14,21,28 days. On 28 days, eyes were, enucleated, vitreous fluids and proliferative vitreous membranes were prepared to be stained by TdT-mediated biotin-dUTP nick-end labeling (TUNEL) method for detection of apoptosis cells. Apotosis cells have been numbered under the light microscope. In the toxicity experiment group ,eyes of rabbits were intravitreal injected 0.1ml alcohol containing 7.5mg indomethacin. The amplitudes(Aa , Ab) and latent times (La, Lb) of a, b-wave of F-ERG were recorded before injection and after 28 days. 28 days later, eyes were enucleated. Retina were prepared for electron-microscopic examination.Result The rapeutic effect of indomethacin : The proliferative degrees of the first three groups show no differences on 7 days after injection (X2=6.00 P=0.05).On 14 , 21 , 28 days , the differences of proliferative degrees of PVR can be observed. The proliferative changes in the treated groups (high-dose group, low-dose group) are fewer compared with those in control group respectively. But there is no difference ofproliferative degree between the treatment groups. [On 14 days : P1=0.04, P2=0.01, P3=0.57 (1: low-dose group vs control group, 2: high-dose group vs control group 3: high-dose group vs low-dose group) . On 21 days : P1=0.04, P2=0.04, P3=0.69. On 28 days : P1=0.00, P2=0.00, P3=0.69. ] Compared to the control respectively, the number of apoptosis cells of the treated groups significantly increased. But there is no difference of apoptosis cell number between the treated groups (P1=0.00, P2=0.00, P3=0.13) .Toxicity of indomethacin on retina: Both La and Lb were significantly prolonged after injection (Pa=0.00, Pb=0.04 ) .Both Aa and Ab were significantly decreased (Pa=0.00, Pb=0.00) . The electron-microscopic examination shows that the ultrastructure of retina were slightly changed.Conclusion Intravitreal administration of indomethacin could decrease the proliferative changes of experimential proliferative vitreoretinopathy induced by platelet-rich plasma and also could induce apoptosis of proliferative cells in vitreous and proliferative membrane. There is some toxic effect on the retina when 7.5mg indomethacin has been injected into vitreous cavity.