Optic coherence tomography (OCT) is one of the most rapid developing technologies in ophthalmology. OCT angiography (OCTA) has been made possible by the development of even faster scanning and sampling techniques, which is the next milestone after stratus OCT and spectral domain OCT. Without the need of injection of the contrast agent, OCTA is capable of providing a three-dimensional reconstruction of the perfused microvasculature within the retina and choroid by detecting the motion of scattering particles such as erythrocytes within sequential OCT cross-sectional scans performed repeatedly at the same location of the eye with different analysis algorithms. Comparing to fundus fluorescein angiography and indocyanine green angiography, with improved OCT technology and understanding, OCTA has showed certain advantages to diagnose retinal and choroidal diseases, especially macular vascular diseases. It is important to establish the contributions that OCTA can make to diagnosing, managing and understanding of ocular fundus diseases.
Objective To investigate the dosage, efficacy and safety of intrav itreal injection of plasmin in producing posterior vitreous detachment (PVD), an d the possible role of plasmin in degrading adhesion glycoproteins of inner limiting membrane (ILM).Methods Twenty eyes of young human cadavers within 24 hours after death were divided into 4 groups that received 0.1 ml balanced salt solution (group 1) as control, 1 (group 2), 2 (group 3), or 3 (group 4) U of human plasmin. Optical and transmission electron microcopies were performed to examine the ultrastructure of the vitreoretinal interface. Electron-immunocytochemical techniques were carried out on ILM to estimate the content of fibronectin (FN) and laminin (LN). Flow cytometry was used for cell viability analysis of variance (ANOVA) and Tukey-test was employed for statistical analysis. Results Microscopy demonstrated that plasmin especially in group 4 cleaved the attachment of the vitreous collagen fibrils to the ILM with no evident damage to the inner retina. The content of LN, FN in ILM decreased with injection of plasmin (group 3 and 4 had statistical significance from control group for FN,P＜0.05; for LN in group 4, P＜0.05). Retinal cell viability was similar for plasmin-treated and control eyes. Conclusion Human plasmin disrupts the attachment of posterior hyaloid to the ILM with no morphologic changes of the inner retina. PVD is induced mostly with injection of 3 U plasmin. (Chin J Ocul Fundus Dis，2003，19：42-45)