Effect of angiotensin Ⅱ type 1 receptor blocker and angiotensin converting enzyme inhibitor on the intraocular growth factors and their receptors in streptozotocin-induced diabetic rats

AIM： To investigate the effect of angiotensin II type 1 receptor blocker （ARB） and angiotensin converting enzyme inhibitor （ACEI） on intraocular growth factors and their receptors in streptozotocin-induced diabetic rats. METHODS： Forty Sprague-Dawley rats were divided into 4 groups： control, diabetes mellitus （DM）, candesartan- treated DM, and enalapril-treated DM （each group, n---10）. After the induction of DM by streptozotocin, candesartan [ARB, 5 mg/（kg · d）] and enalapril [ACEI, 10 mg/（kg · d）] were administered to rats orally for 4Wko Vascular endothelial growth factor （VEGF） and angiotensin II （Ang II） concentrations in the vitreous were measured using enzyme-linked immunosorbent assays, and VEGF receptor 2 and angiotensin II type 1 receptor （ATIR） levels were assessed at week 4 by Western blotting. RESULTS： Vitreous Ang II levels were significantly higher in the DM group and candesartan-treated DM group than in the control （P=0.04 and 0.005, respectively）. Vitreous ATIR increased significantly in DM compared to the other three groups （P〈0.007）. Candesartan-treated DM rats showed higher vitreal ATIR concentration than the enalapril-treated DM group and control （P〈0.001 and P=0.005, respectively）. No difference in vitreous Ang II and ATIR concentration was found between the enalapril- treated DM group and control. VEGF and its receptor were below the minimum detection limit in all 4 groups. CONCLUSION： Increased Ang II and ATIR in the hyperglycemic state indicate activated the intraocular renin-angiotensin system, which is inhibited more effectively by systemic ACEI than systemic ARB.

Evaluation of the safety of anterior capsule staining with trypan blue under air: a retrospective analysis

AIM: To evaluate the safety of using 0.03% trypan blue under air for anterior capsule staining in cataract surgery.METHODS: The current study involved a retrospective analysis of the medical records of 86 patients with vitreous hemorrhage, who underwent pars plana vitrectomy and cataract surgery.The patients were classified into two groups.The trypan blue group(n=45) comprised patients who underwent anterior capsule staining with 0.03% trypan blue under an air bubble.The control group(n=41) comprised of patients who underwent intracameral illuminator-assisted capsulorhexis.The status of endothelial cell density(ECD) in both the groups was analyzed.RESULTS: The trypan blue group displayed significant decline in ECD at 1 mo(7.91% loss, P<0.001) and 3 mo(9.65% loss, P<0.001) after the surgery, whereas no significant changes were observed in the control group.Moreover, the number of patients who did not display a postoperative decline in ECD was significantly higher in the control group(43.9%;18 patients) than in the trypan blue group(17.1%;7 patients, P=0.004).CONCLUSION: Anterior capsule staining with trypan blue under the air bubble would not be as safe as the intracameral illuminator.The ECD loss might be attributed to the air bubble rather than to the deleterious effects of 0.03% trypan blue.Further studies are required to clarify this.

Macular hole closure induced by intravitreal injection in diabetic macular edema

Dear Editor,Macular hole(MH)formation is uncommon in patients with diabetic macular edema(DME).Few cases of MH associated with DME treatment have been described,including a report of four out of eight eyes with MH and diabetic retinopathy(DR)having DME[1].However,no case of resolution of MH after DME treatment has been reported.We report three consecutive cases of MH closure achieved by intravitreal injection for DME treatment.

Retinal injury following intravitreal injection of a dexamethasone implant in a vitrectomized eye

Lee SM, Jung JW, Park SW, Lee JE, Byon IS. Retinal injury following intravitreal injection of a dexamethasone implant in a vitrectomized eye. Int J Ophthalmo12017; 10（6）： 1019-1020

Induction of vascular endothelial growth factor receptor expression in human umbilical vein endothelial cells after repeated bevacizumab treatment in vitro

AIM： To investigate the mechanism underlying the loss of responsiveness to anti-vascular endothelial growth factor（VEGF） treatment after repeated injections for choroidal neovascularization, VEGF and VEGF receptor（VEGFR） expressions were evaluated following repeated bevacizumab treatments in hypoxic human umbilical vein endothelial cells（HUVECs） in vitro.METHODS： HUVECs were incubated under hypoxic conditions in two media of different bevacizumab concentrations（1.0 or 2.5 mg/m L） for 17 h, and then in a new medium without bevacizumab for 7h. This procedure was repeated twice more. A culture with an identical volume of excipients served as the control. Cytotoxicity and cell proliferation were assessed using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide and Ki-67 assays, respectively. Levels of VEGF and VEGFR were assessed using enzyme-linked immunosorbent assay and Western blot respectively.RESULTS： Cytotoxic effects were not reported for either bevacizumab concentration. Cell proliferation was not reduced after anti-VEGF treatments. VEGF level after single treatment was significantly higher than that of the control and after repeated treatments. Phosphorylated VEGFR-2 expression increased significantly after singleand repeated bevacizumab treatments compared with the control. The 1.0 mg/m L bevacizumab induced significantly higher expressions of VEGFR-2 than the 2.5 mg/m L in single and repeated treatment groups.CONCLUSION： Bevacizumab treatment of HUVECs elevated VEGFR expression in both single and repeated treatments, indicating a mechanism for the reduced efficacy of anti-VEGF therapy in ocular neovascular disorders.