Mechanism Of Intraocular Use Of Triamcinolone Acetonide In Controlling Intraoperative Bleeding In Vitrectomized Eyes With Proliferative Diabetic Retinopathy

Objective: To explore the mechanism of intraocular use of triamcinolone aceto nide(TA)in controlling intraoperative bleeding in vitrectomized eyes with prol iferative diabetic retinopathy(PDR).Methods: Part I: The authors conducted a retrospective study of 25 patients(29 eyes)underwent vitrectomy for severe PDR.During operation,vitreous and easy stripped proliferative membranes were removed as possible.After peeling proliferative membranes,retinal hemorrhaging or small blood vessel bleeding o ccurred,and TA(4 mg/0.1 ml)was then applied followed by further removal of residual vitreous and proliferative membranes.Patients' intraoperative and po stoperative bleeding,best corrected visual acuity,intraocular pressure,and com plications were assessed.Part II: Twelve eyes of 12 patients who receivedvitre ctomy combined with the intraocular injection of TA intraoperatively for PDR were as TA group.Thirty-two eyes of 32 patients who underwent vitrectomy f or epimacular membrane or macular hole were involved in control group.The vitreous specimens were collected in all vitrectomized eyes.The concentrations of vitreous u-PA,t-PA,and PAI-1 from TA and control groups were measured with enzyme linked immunosorbent assay-sand(ELISA)and compared respectiv ely.Results: Part I: After TA injection,the retina in all patients became slightly p ale.Retinal hemorrhaging or small blood vessel bleeding was controlled or sto pped.Remnant retinal hemorrhage was not cleared in 9 eyes(31.03%)by post operative week 1 and in 4 eyes(13.79%)by month 1.All eyes(100%)maint ained retinal hemorrhage-free condition on month 3.At last follow-up,visual a cuity improved in 25 eyes(86.21%),and unchanged in 4 eyes(13.79%).None got decreased visual acuity.Intraocular pressure elevation occurred in 8 eyes(27.59%)at early phase postoperatively and the pressure in seven ofthem was co ntrolled in normal range within two weeks after anti-glaucoma treatments.The other one eye required trabeculectomy on postoperative week 4and the intraocu lar pressure was controlled after operation.Cataract progressionwas noticed in 3 eyes(3/14,21.43%).No recurrent retinal hemorrhage,endophthalmitis or oth er complications were recorded during follow up period.Part II:The median le vels of vitreous u-PA,t-PA,and PAI-1 were 25.45ng/m L,127.44ng/m L,and 0.42ng/m L respectively in TA group.The median levels of vitreous u-PA,t-PA,a nd PAI-1 were 22.94ng/m L,142.37ng/m L,and 0.27ng/m L respectively in contr ol group.Level of vitreous u-PA in TA group was significantlyhigher than that in control group.(Z=-2.268,P<0.05),and there were no significant difference i n vitreous t-PA and PAI-1 between TA and control groups.(Z=-0.092?-1.847,P>0.05).Conclusion: TA injection during vitrectomy for PDR in proper time effectively controlled the intraoperative retinal bleeding,reduced the operative time,and i mproved the safety of surgery.There is a tendency for vitreous hemorrhage wi th the increase of vitreous u-PA expression in PDR patients.The mechanismofi ntraoperative hemorrhage stopping under the intraocular use of TA may be rela tive to decreasing vitreous t-PA and u-PA expression as well as increasing PAI-1 expression.