Macular microvascular changes after intravitreal bevacizumab injection in diabetic macular edema.

OBJECTIVE: To evaluate the changes in retinal capillary plexus and the choriocapillaris after a single intravitreal injection of bevacizumab in eyes with diabetic macular edema using optical coherence tomography angiography (OCTA). DESIGN: Prospective interventional case series. PARTICIPANTS: Patients having diabetes with centre-involving diabetic macular edema. METHODS: In this prospective interventional case series, eyes with centre-involving diabetic macular edema were enrolled. Vascular density (VD), vascular diameter index (VDI), vascular length density (VLD), foveal avascular zone (FAZ) area, and foveal density (FD)-300 were measured using en face OCTA images before and 1 month after administration of intravitreal bevacizumab. VD and VDI measurements were performed in the superficial capillary plexus (SCP) and deep retinal capillary plexus (DCP) and in the choriocapillaris. Additionally, capillary nonperfusion area (CNPA) was detected automatically based on vessel distance map in 4 concentric rings around the foveal centre. The segmentation error was manually corrected, and the measurements were performed by 2 expert graders. RESULTS: Twenty-three eyes of 19 patients with a mean age of 62.76 ± 6.88 years were included. There were no significant changes in the FAZ area, FD-300, or in the VD of the foveal and parafoveal SCP and DCP. Also, VLD and VDI of the SCP and DCP remained unchanged. The change in the CNPA was not statistically significant. The VD of choriocapillaris increased significantly after injections (p = 0.005). CONCLUSIONS: FAZ area and VD of the retinal capillary plexus remained stable in the short-term period after intravitreal bevacizumab. In addition, the choriocapillaris blood flow improved after bevacizumab injection.

Seasonality of Acute Retinal Necrosis.

PURPOSE: To study the seasonal variability in the occurrence of acute retinal necrosis (ARN) in a series of polymerase chain reaction (PCR)-positive patients. METHODS: Consecutive patients clinically diagnosed with ARN and a positive PCR result of aqueous humor during a seven-year period were studied retrospectively. Patients' demographics, causative viral agent(s), and the date of disease onset were extracted from medical records. RESULTS: Twenty eyes of 20 patients were enrolled; the mean age at presentation was 39.6 ± 14.4 (range, 6-62) years. Nine patients were female. The most common causative agent was varicella-zoster virus in 16 patients (80%), followed by herpes simplex virus in two patients (10%). The disease onset was in winter in 10 patients (50%), and the highest incidence was in February (five patients, 25%). The cumulative occurrence of ARN was significantly higher in the first half of the year (winter and spring) compared to the second half of the year (summer and fall) (P = 0.030). In general, seasons with a high incidence of ARN were preceded by cold seasons. CONCLUSION: In our series, we observed seasonal variability in the incidence of ARN, with the highest incidence during winter and spring. However, further epidemiologic studies in different geographical areas are required to elucidate the true seasonal nature of ARN.

Safety of the subconjunctival injection of doxycycline in rabbits.

Purpose: To evaluate the safety of subconjunctival injection of doxycycline in rabbit eyes. Methods: Eight white New Zealand rabbits were selected. Different concentrations of 250 micrograms (µg), 500 µg, 1000 µg, and 2000 µg in 0.1 ml were prepared for subconjunctival injection. Each concentration was injected into the two eyes of each rabbit. For each dose, dextrose was injected in one contralateral eye and the other fellow eye remained non-injected. All rabbits underwent ocular examination in the 1st, 3rd, and 30th day after injection. The rabbits were sacrificed 30 days after injections and the histopathological examination was performed. Results: No obvious change was detected in all four groups from the 1st day to the 3rd day after injection in terms of tearing, hyperaemia, and chemosis. There was no visible sign of inflammation or necrosis, and also no histological change in both clinical and histopathological examinations. Conclusion: Subconjunctival injection of doxycycline with different dosages of 250 to 2000 ug in 0.1cc in rabbit eyes was safe and no clinical or histological changes were observed after one month.

TIME COURSE OF CHANGES IN OPTIC DISK NEOVASCULARIZATION AFTER A SINGLE INTRAVITREAL BEVACIZUMAB INJECTION.

PURPOSE: To evaluate the longitudinal changes in optic disk neovascularization (NVD) after intravitreal bevacizumab injection using optical coherence tomography angiography. METHODS: In this prospective, interventional, case series, eyes with NVD secondary to diabetic retinopathy were enrolled. En face optical coherence tomography angiographic images were obtained from the optic disks before and 3 hours, 6 hours, 24 hours, 7 days, and 30 days after intravitreal bevacizumab injection. The size and flow area of the neovascularization were measured by two graders. RESULTS: Eleven eyes of 9 patients with a mean age of 52.11 ± 9.48 years were included. The reduction in the NVD size and flow area was statistically significant at 24 hours, 7 days, and 30 days after injections compared with the baseline measurements (all P < 0.05). The decremental regression in the NVD size and flow area continued during the study course. The changes were not statistically significant in 3-hour and 6-hour measurements (all P > 0.05). CONCLUSION: In this study, statistically significant regression in the NVD size and flow area was observed as early as 24 hours after a single intravitreal bevacizumab injection, with a continued decreasing trend for at least a 1-month period.