Estudo experimental da inibição da proliferação vitreorretiniana pelo uso da hiperecina / Experimental study of vitreoretinal proliferation inhibition by the use of hypericin

OBJETIVOS: Induzir a produção de membranas vitreorretinianas em modelo de trauma ocular animal. Avaliar a inibição do desenvolvimento da proliferação vitreorretiniana (PVR) com o uso de hiperecina. MÉTODOS: Estudo Experimental. Foram utilizados 19 coelhos machos pigmentados adultos com peso entre 2.000 e 3.000 gramas. Todos submetidos a modelo de trauma com dispase associada à diatermia da retina para indução de membranas de PVR. Separados randomicamente para receberem hiperecina (10 µM em 0,1 ml) ou solução salina (0,1 ml) como placebo. Avaliados clinicamente no sétimo, décimo quarto, vigésimo primeiro e vigésimo oitavo dias de pós-operatório com oftalmoscopia indireta e retinografia colorida digitalizada. O grau de PVR foi classificado em estágios (de 0 a 7) segundo Hida e colaboradores. RESULTADOS: A formação de membranas esteve presente em 79 por cento dos olhos, sendo 100 por cento nos olhos do grupo placebo e 60 por cento nos olhos do grupo tratamento (hiperecina). A comparação entre as médias dos estágios de PVR entre os grupos mostrou diferença estatisticamente significativa, com valor p=0,0321 pelo teste Wilcoxon. CONCLUSÕES: O modelo de trauma com uso de dispase e diatermia da retina produz membranas vitreorretinianas. A hiperecina mostrou-se eficaz na diminuição do aparecimento e progressão do PVR.

PURPOSE: To produce proliferative vitreoretinopathy (PVR) in an animal ocular trauma model. To evaluate the inhibition of (PVR) emergence and progression by hypericin. METHODS: Experimental Study. Nineteen pigmented male adult rabbits weighing between 2,000 and 3,000 grams were used in this study. All of them were submitted to trauma model with dispase and retinal diathermy to induce PVR membranes formation. They were randomly assigned to receive hypericin (10 µM in 0.1 ml) or saline solution (0.1 ml) as placebo. They were evaluated clinically in the seventh, fourteenth, twenty-first and twenty-eighth postoperative days with indirect ophthalmoscopy and digital color retinography. The PVR degree was classified according to Hida (0 to 7). RESULTS: Membranes formation was present in 79 percent of the eyes; being 100 percent in the eyes of placebo group and 60 percent in the eyes of treatment group (hypericin). The comparison between PVR phases averages within the groups showed a statistically significant difference between the two groups, with a p value of 0.0321 for Wilcoxon test. CONCLUSIONS: The trauma model with dispase and retinal diathermy produces vitreoretinal membranes. Hypericin was considered effective in PVR emergence and progression decrease.

The effect of subtenon injection of methylprednisolone acetate on the breakdown of blood retinal barrier after cryotherapy

Using computerized vitreous fluorophotometry (VFP, Fluorotron(TM)), we examined the effect of cryotherapy on the blood retinal barrier (BRB) and the effect of subtenon injection of methylprednisolone acetate (Depomedrol(R)). In experiment 1, the right eyes of the 13 pigmented rabbits were treated with heavy cryotherapy after baseline VFP readings. The freezes were applied at 6 places in each quadrant around the equator are in two rows, a total of 24 places circumferentially. The left eyes were reserved as controls. In 6 rabbits (cryo with steroid group), Depomedrol(R) 10 mg of Depomedrol was injected into subtenon space after cryotherapy. The other 7 rabbits were treated with cryotherapy only (cryo only group). The VFP readings were taken 1, 3, 5, and 7 days, 2, 3, 5, and 7 weeks after cryotherapy. Cryotherapy increased the breakdown of BRB significantly. The peak VFP readings were obtained 5 days after cryotherapy in the cryo only group and 7 days after cryotherapy in the cryo with steroid group. In the cryo only group, the severity of the breakdown of BRB was higher than in the cryo with steroid group, and the increased VFP readings could not be normalized until 7 weeks after cryotherapy. In experiment 2, both eyes of the 8 pigmented rabbits were treated with medium cryotherapy after baseline VFP readings. The freezes were applied at 3 places in the superior temporal quadrant and at 3 places in the superior nasal quadrant, a total of 6 places. Depomedrol(R) 10 mg was injected into subtenon space after cryotherapy in the right eyes only. The VFP readings were taken 1, 3, 5, 7, 10, and 14 days after cryotherapy. In this experiment, cryotherapy did not increase the breakdown of BRB. But in the right eye, the severity of the breakdown of BRB was significantly lower than in the left eye 7 and 10 days after cryotherapy. These results suggest that Depomedrol(R) can decrease the severity of the breakdown of BRB after cryotherapy, and may be useful in the prevention of proliferative vitreoretinopathy (PVR).