[A Case of Advanced Gastric Cancer Treated with Conversion Surgery followed by Nivolumab Combination Chemotherapy].

The use of nivolumab as first-line therapy for unresectable advanced gastric cancer has now become a standard practice, and its efficacy has been established. This is the first report of a patient with advanced gastric cancer who underwent conversion surgery after first-line nivolumab combination chemotherapy. The patient was a 58-year-old woman. Her medical history included hypertension and dyslipidemia. She had advanced gastric cancer with extensive lymph node metastasis in the left supraclavicular fossa and around the abdominal aorta. After confirming the HER2-negative status and the PD-L1 CPS score to be ≥5, nivolumab was administered in combination with chemotherapy. After the treatment, she underwent a total gastrectomy with D2 dissection, combined splenectomy and pancreatic tail resection for adhesions, and para-aortic lymph node sampling as a conversion surgery. There was no obvious cancerous remnant in the resected specimen, and the pathological response was Grade 3. The patient was alive and recurrence-free at 4 months postoperatively.

Assessing effects of mechanical stimulation of fluid shear stress on inducing matrix Metalloproteinase-9 in cultured corneal epithelial cells.

Blinking is regarded as mechanical stimulation of fluid shear stress on the corneal epithelial cells. Therefore, we evaluated whether fluid shear stress affects matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in cultured human corneal epithelial cells (HCECs). No other study has shown the influence of fluid shear stress on HCECs regarding mRNA expression and the protein levels of MMPs. Cultured HCECs were exposed to shear stress (0, 1.2, 12 dyne/cm2) for 12 and 24 h with the parallel-plate type of flow chamber. Gene expression of MMPs and TIMPs was measured by real-time polymerase reaction. Concentrations of MMP-1 and MMP-9 in cell lysates were determined using bead-based amplified luminescent proximity homogenous assay-linked immunosorbent assay. The expression of MMP-9 and MMP-1 in HCECs exposed to low and high flow for 12 and 24 h, respectively, increased significantly compared with those under static conditions. The expression of MMP-9 in the cells exposed to high flow for 24 h increased significantly compared with those under static and low flow conditions. Levels of MMP-9 in cell lysates exposed to fluid flow for 24 h were elevated significantly with increasing shear stress. Fluid shear stress exerted on HCECs affected MMPs, which was associated with inflammation and pathogenesis. Mechanical stress induced by blinking might influence expression of MMPs on the ocular surface. Further studies are warranted to establish the molecular mechanism of shear stress-induced alternations of MMPs.

[Recurrence-Free Survival after Repeated Resections for Metastatic Inguinal Tumor in Colorectal Mucinous Adenocarcinoma-A Case Report].

A 79-year-old male presented with right inguinal mass and right leg pain. Laparoscopic right hemicolectomy was performed for transverse colon cancer(type 1, muc, pSS, pN1a, pStage Ⅲa)3 years and 6 months ago. We resected the mass located in the spermatic cord and reconstructed it using the Direct Kugel Patch. Histopathological examination revealed mucinous carcinoma and was diagnosed as a metastatic lesion. Local recurrence was detected in the spermatic cord 1 year after resection, and radical inguinal orchiectomy was performed. Six months after the surgery performed for local recurrence, repeated recurrence was detected in the mesh used for reconstruction. Because this recurrence time was short, the patient opted for chemotherapy; however, this resulted in tumor growth, and surgery had to be scheduled. We performed extended resection of the abdominal wall and reconstruction using the fascia lata tensor muscle flap. Although intestinal obstruction, aspiration pneumonia, and skin flap necrosis were observed, the patient was discharged on the 85th postoperative day and remained alive without recurrence for 17 months. Mucinous carcinoma tends to cause local recurrence and requires adequate surgical margin resection. Extended excision should be considered in such cases of repeated local recurrence without distant metastases.

[A Case of Boderline Resectable Pancreatic Cancer Curatively Resected after Chemotherapy with Gemcitabine and Nab-Paclitaxel].

Combination therapy containingnab -paclitaxel(nab-PTX)and gemcitabine(GEM)is widely administered for metastatic pancreatic cancer. Recently, this regimen is likely to be applied for treatment in patients with locally advanced disease or for neoadjuvant chemotherapy(NAC)in patients with borderline resectable(BR)pancreatic cancer. We report a case of BR pancreatic cancer in a patient who was eligible for comparison of the imaging findings with the microscopic findings of the resected specimen. A 72-year-old woman was admitted to our hospital with a complaint of jaundice. Enhanced CT showed a 35mm tumor at the head of the pancreas involvingthe portal vein and in contact with the superior mesenteric artery(SMA). After 4 courses of chemotherapy containinga combination of nab-PTX and GEM, the tumor reduced in size, but was still in contact with the portal vein and SMA on imaging. The level of tumor marker CA19-9 was remarkably reduced. Subtotal stomach-preservingpancreaticoduodenectomy with portal vein reconstruction was performed. Macroscopic findings of the cut surface of the resected specimen showed that a white nodule at the pancreas head involved the portal vein and was in contact with the close-cut margin from the SMA; however, microscopic findings revealed that tumor cells had disappeared in the plexus around the SMA. R0 resection was achieved. The histological treatment effect based on Evans' classification and TNM classification were GradeⅡ and pT3N1aM0(pStage ⅡB), respectively. There has been no recurrence 15 months after the surgery. Based on the abovementioned findings, chemotherapy containing a combination of nab-PTX and GEM can be an effective option of NAC for BR-A pancreatic cancer. Even if the tumor is in contact with the SMA on imaging, when the CA19- 9 level is markedly reduced, there is a possibility of achievingR0 surgery.

Mechanism of Developmental Effects in Rats Caused by an N-Phenylimide Herbicide: Transient Fetal Anemia and Sequelae during Mid-to-Late Gestation.

BACKGROUND: Rat developmental toxicity including embryolethality and teratogenicity (mainly ventricular septal defects [VSDs] and wavy ribs) was produced by an N-phenylimide herbicide that inhibits protoporphyrinogen oxidase (PPO) common to chlorophyll and heme biosynthesis. Major characteristics of the developmental toxicity included species difference between rats and rabbits, compound-specific difference among structurally similar herbicides, and sensitive period. Protoporphyrin accumulation in treated fetuses closely correlated with the major characteristics. Iron deposits in erythroblastic mitochondria and degeneration of erythroblasts were observed in treated rat fetuses. In this study we investigated fetal anemia and subsequent developmental effects in rats, and inhibition of PPO in rats, rabbits, and humans by the herbicides in vitro. METHODS: Fetuses were treated on gestational day (GD) 12 and removed on GDs 13 through 20. All litters were examined externally. One half of litters were examined for blood and skeletal development, and the other half for interventricular foramen closure. Effects on PPO were determined in mitochondria from embryos and adult livers. RESULTS: Fetal anemia in rats was evident on GDs 13 through 16. Subsequently, enlarged heart, delayed closure of the foramen, reduced serum protein, and retarded rib ossification were observed. In vitro PPO inhibition exhibited species- and compound-specific differences corresponding to the developmental toxicity. CONCLUSION: We propose that developmental toxicity results from PPO inhibition in primitive erythroblasts, causing transient fetal anemia followed by death. Compensatory enlargement of the fetal heart results in failure of interventricular foramen closure and VSD. Reduced serum protein leads to delayed ossification and wavy ribs.

Effect of intravitreal Rho kinase inhibitor ripasudil (K-115) on feline retinal microcirculation.

Ripasudil (K-115) is a novel Rho kinase inhibitor with a potent intraocular pressure-lowering effect. However, it is unclear whether ripasudil affects the retinal blood flow (RBF). We investigated the effect of ripasudil on feline retinal microcirculation. Ripasudil (5 µM, 50 µM or 5 mM; n = 5 each concentration) or vehicle (PBS; n = 5) was injected intravitreally. The vessel diameter (D) and blood velocity (V) were measured by laser Doppler velocimetry simultaneously in the first-order retinal arterioles and the RBF was calculated. The measurements started 5 min before the injection and were performed every 10 min for 120 min. After the intravitreal injection, the retinal circulatory parameters did not change significantly in PBS or 5 µM of ripasudil. The blood V and RBF increased significantly compared to baseline, whereas the vessel D did not change significantly in 50 µM and 5 mM of ripasudil. The V in 50 µM, and the V and RBF in 5 mM of ripasudil significantly increased compared to those in PBS. Intravitreal administration of ripasudil increased the blood V and RBF in cats, suggesting that ripasudil has the potential to improve the retinal blood flow.

[A Case of Locally-Advanced Breast Cancer with Liver Metastasis, Treated with Mastectomy of the Primary Tumor after Chemotherapy].

The patient was a 39-year-old woman who was referred to our hospital with suspicion of locally-advanced breast cancer. After several tests, she received a diagnosis of cT4bN1M1 (liver), Stage Ⅳbreast cancer. The liver metastasis was located in S4, and was 1 cm in size. Core needle biopsy was performed on the breast tumor; the pathological diagnosis was invasive ductal carcinoma (scirrhous carcinoma), nuclear Grade (NG) 3, and HER2-positive. She received epirubicin plus cyclophosphamide (EC) followed by docetaxel (DOC) plus pertuzumab (PER) plus trastuzumab (HER). After chemotherapy, the liver metastasis and axillary lymph node metastases had disappeared on imaging findings, showing a complete response (CR), but the primary breast tumor remained, showing a partial response (PR). She underwent mastectomy and axillary lymph node dissection for local control. After surgery, no metastases including liver metastases were seen on CT. The patient is currently receiving tamoxifen and anti-HER2 therapy.

[A Case of Pathologically Complete Response of a Rectal Cancer after Preoperative Treatment with mFOLFOX6 and Radiation Therapy].

A 60-year-old man who had bloody stools after sigmoid colonoscopy was admitted to our hospital. A digital examination and sigmoid colonoscopy showed a type 2 circular tumor at location Rb with incomplete mobility and tumor hemorrhage, and the result of a biopsy was moderately differentiated adenocarcinoma (tub2). Computed tomography and magnetic resonance imaging suggested a possibility of invasion of the primary rectal tumor to the sacrum. The clinical stage was cT4bN0M0H0P0, cStage Ⅱ, which is generally not treatable by surgery. Sigmoid colostomy was performed, and a central venous port was implanted. After a preoperative treatment consisting of 3 courses of mFOLFOX6 and radiation therapy, the clinical stage changed to ycT2N0M0H0P0, ycStageⅠ. Super-low anterior resection and covering ileostomy were performed 46 days after the preoperative treatment. A pathological examination revealed no residual cancer cells in the primary lesion and lymph node (Grade 3, pCR). The patient has been disease-free for 4 years and 9 months after the operation.

[A Case of Malignant Phyllodes Tumor Effectively Treated by Radiation Therapy as a Palliative Medicine].

The current report presents the case of a 46-year-old woman with phyllodes tumor metastasis to the anterior chest wall treated by radiation therapy. Although the lesion was not controlled with surgery and chemotherapy, the tumor size markedly reduced after radiation therapy, and bleeding and foul odor from the tumor stopped. Radiation therapy for phyllodes tumor appears to be an effective treatment and should be recognized as one choice of palliative medicine.

Role of Ca2+ -dependent and Ca2+ -sensitive mechanisms in sphingosine 1-phosphate-induced constriction of isolated porcine retinal arterioles in vitro.

Although sphingosine 1-phosphate (S1P), a bioactive lipid derived from activated platelets, has a variety of physiologic effects on vessels, no reports have described the effect of S1P on the retinal circulation. We examined the effect and underlying mechanism of the vasomotor action of S1P on porcine retinal arterioles. The porcine retinal arterioles were isolated, cannulated, and pressurized without flow for in vitro study. S1P-induced diameter changes were recorded using videomicroscopic techniques. S1P elicited concentration-dependent (1 nM-10 µM) vasoconstriction of the retinal arterioles that was abolished by the S1P receptor 2 (S1PR2) antagonist JTE-013. S1P-induced vasoconstriction was abolished by the Rho kinase (ROCK) inhibitor H-1152 and was inhibited partly by the protein kinase C (PKC) inhibitor Gö-6983. The inhibition of phospholipase C by U73122 and L-type voltage-operated calcium channels (L-VOCCs) by nifedipine inhibited S1P-induced vasoconstriction; a combination of both inhibitors abolished S1P-induced vasoconstriction. Furthermore, inhibition of myosin light chain kinase (MLCK) by ML-9 significantly blocked S1P-induced vasoconstriction; further coadministration of ML-9 with H-1152 or Gö-6983 abolished S1P-induced vasoconstriction. The current data suggest that S1P elicits vasoconstriction of the retinal arterioles via S1PR2 in vascular smooth muscle cells and this vasoconstriction may be mediated by the Ca2+ -sensitive pathway via activation of PKC leading to activation of ROCK and the Ca2+ -dependent pathway via activation of L-VOCCs resulting in activation of MLCK.

[A case of adenosquamous carcinoma of the sigmoid colon with inferior mesenteric vein thrombosis].

A 63-year-old man who had been admitted to another institute with sepsis and renal failure was referred to our hospital after computed tomography (CT) findings showed thickening of the walls in the sigmoid colon and a defect in contrast enhancement in the portal and inferior mesenteric veins. Emergency sigmoid colon resection with D2 lymphadenectomy was performed after detection of perforation due to sigmoid colon cancer. The histopathological diagnosis was adenosquamous carcinoma, pSS, int, INF b, ly1, v0, pN2, pStage IIIband inferior mesenteric vein thrombosis. He was discharged on day 12, and we administered anticoagulant warfarin therapy.

[A case of sigmoid colon cancer with abdominal wall abscess].

A 63-year-old man was admitted for an abdominal mass. Computed tomography revealed an abscess (21 × 20 cm) in the abdominal wall and a tumor in the sigmoid colon. Thus, cancer of the sigmoid colon complicated by an abscess of the abdominal wall was diagnosed. The abscess was drained and transverse colostomy was performed with curative intent. After the intervention, chemotherapy (XELOX×3) was administered. Three months later, sigmoidectomy was performed and the stoma was closed. Macroscopic and microscopic examination of the resected specimen detected no remnants of cancer. In patients with advanced colon cancer and abdominal wall involvement, a two-stage operation and preoperative chemotherapy may be considered essential when curative resection is performed.

[Long-term survival of a patient with esophageal cancer with brain metastasis after multidisciplinary therapy - a case report].

A 70-year-old woman was admitted for difficulty in swallowing. Esophageal cancer (MtLt, type 3, T4N3M0, cStage IVa) was diagnosed in May 2010. The cancer was unresectable, and chemoradiotherapy (CRT) with TS-1 was initiated in June 2010, and a partial response (PR) was observed. After CRT, TS-1 was continued, but a brain metastasis was detected owing to the development of right hemiplegia in April 2012. Craniotomy and tumorectomy were performed, and the right hemiplegia improved. Pathological examination of the brain tumor indicated squamous cell carcinoma. Because of a recurrence of brain metastasis, a gamma knife procedure was performed in May 2012. Subsequently, several recurrences of brain metastases were diagnosed, and a total of 7 gamma knife procedures were performed up to January 2014. Although systemic chemotherapy (5-fluorouracil and cisplatin [FP], 5 courses)was administered, the patient showed progressive lung metastases in February 2013. The chemotherapy regimen was changed from FP to docetaxel (TXT), but the lung metastases continued to progress up to June 2013. The patient died in March 2014. Patients with esophageal cancer and metastases to the brain have poor prognosis, but the present patient survived approximately 2 years after first diagnosis of metastases to the brain after multidisciplinary therapy.

Glaucoma Diagnostic Performance of Retinal Blood Flow Measurement With Doppler Optical Coherence Tomography.

Purpose: The purpose of this study was to evaluate the diagnostic performance of retinal blood flow (RBF) measured with the Doppler optical coherence tomography (OCT) segmental scanning method to distinguish between healthy and glaucoma eyes. Methods: Fifty-eight patients with normal tension glaucoma (NTG) who had a single-hemifield visual field defect and 44 age-matched healthy subjects were enrolled. Retinal nerve fiber layer thickness (RNFLT) was measured with swept-source OCT. Superior and inferior temporal arteries (TAs) and temporal veins (TVs) RBF were measured with Doppler OCT. The area under the curve (AUC) of the receiver operating characteristic (ROC) was used to compare the diagnostic performances in the damaged and normal hemispheres. Results: Multivariate regression analysis showed TA RBF and TV RBF were significantly reduced in the damaged and normal hemispheres. The ROC analysis showed that the AUC for quadrant RNFLT, TA RBF, and TV RBF were 0.973, 0.909, and 0.872 in the damaged hemisphere, respectively. The AUC values in the normal hemisphere were 0.783, 0.744, and 0.697, respectively. The combination of quadrant RNFLT and TA/TV RBF had a greater AUC than quadrant RNFLT alone in both damaged (AUC = 0.987) and normal (AUC = 0.825) hemispheres. Conclusions: In NTG eyes with single-hemifield damage, the RBF was found to be significantly reduced in the damaged and normal hemispheres independent from structural changes. The combination of RNFLT and RBF could improve diagnostic performances for glaucoma. Translational Relevance: Combining morphological and blood flow measurements with Doppler OCT may be useful in glaucoma diagnosis.

Effect of insulin treatment on pulsatility ratio and resistance index of the retinal artery in patients with type 2 diabetes.

This study aimed to evaluate whether long-term insulin treatment is associated with abnormalities in retinal circulation in type 2 diabetic patients. We evaluated 19 eyes of nondiabetic individuals and 68 eyes of type 2 diabetic patients. The eyes of diabetic patients were classified into two groups according to the presence or absence of long-term insulin therapy. We used a Doppler optical coherence tomography flowmeter to measure diameter, velocity, and blood flow in the major temporal retinal artery. The pulsatility ratio (PR) and resistance index (RI), indices of vascular rigidity, were calculated from the blood velocity profile. PR and RI were significantly elevated in type 2 diabetic patients compared with nondiabetic subjects (P < 0.05). In type 2 diabetes patients, PR and RI were significantly higher in patients receiving long-term insulin treatment than in those without (P < 0.01). There was a significant difference in velocity (P < 0.05), but not diameter and blood flow, between nondiabetic subjects and type 2 diabetes patients. No significant difference in diameter, velocity, or blood flow was observed between the groups with and without long-term insulin treatment. Long-term insulin treatment can affect PR and RI, which might be associated with vascular rigidity of the retinal artery in patients with type 2 diabetes.

Retinal blood flow reduction in normal-tension glaucoma with single-hemifield damage by Doppler optical coherence tomography.

AIMS: To evaluate the associations between retinal blood flow (RBF) and optical coherence tomography (OCT) structural measurements in normal-tension glaucoma (NTG) eyes with single-hemifield visual field (VF) damage by the Doppler OCT. METHODS: The Doppler OCT was used to measure temporal artery (TA) RBF and temporal vein (TV) RBF. Retinal nerve fibre layer thickness (RNFLT) was measured by spectral-domain OCT. RESULTS: Forty-three consecutive eyes of 43 patients with NTG with VF defect confined to a single hemifield and 24 eyes of 24 age-matched healthy subjects were studied. TA and TV RBF and RNFLT were reduced in the damaged hemisphere compared with the normal hemisphere (mean (SD), 3.61 (1.68) vs 5.86 (2.59) µL/min, p<0.001; 5.61 (2.51) vs 6.94 (2.83) µL/min, p=0.010; 69.0 (19.7) vs 99.7 (22.8) µm, p<0.001). Those values in the normal hemisphere of NTG eyes also decreased compared with the healthy hemisphere of the healthy eyes (8.40 (3.36) µL/min, p<0.001; 9.28 (4.47) µL/min, p<0.002; 122.8 (20.2) µm, p<0.001). Multivariate model showed that normal and damaged hemispheres and RNFLT were associated with RBF reduction. In addition, the RBF in the normal hemisphere was lower than that in the healthy hemisphere even after adjusting for RNFLT. CONCLUSION: In NTG eyes with single-hemifield damage, the RBF was significantly reduced in the damaged hemisphere compared with the normal one. The RBF decreased in the normal and damaged hemispheres of NTG eyes compared with the healthy hemisphere independent from RNFLT.

Retinal Blood Velocity Waveform Characteristics With Aging and Arterial Stiffening in Hypertensive and Normotensive Subjects.

Purpose: We aimed to explore the velocity waveform characteristics of the retinal artery associated with age and the cardio-ankle vascular index (CAVI) as a conventional arterial stiffness marker by applying the Doppler optical coherence tomography (DOCT) flowmeter. Methods: In this cross-sectional study, DOCT flowmeter imaging was performed in 66 participants aged 21 to 83 years (17 men, 49 women) with no history of eye diseases and no systemic diseases, except for hypertension. Retinal blood velocity waveform was analyzed where several parameters in time (upstroke time, T1, T2, T3, and T4) and area under the waveform (area elevation, area declination, A1, A2, A3, and A4) were extracted. Systolic blood pressure-adjusted Pearson's coefficients were calculated to determine the correlations of each parameter with age or CAVI. Results: Corrected upstroke time (UTc) was the waveform parameter most positively correlated with age (r = 0.497, P < 0.001). Area declination was the waveform parameter most negatively correlated with age (r = -0.682, P < 0.001) and CAVI (r = -0.601, P < 0.001). Conclusions: We extracted the waveform parameters associated with the risks of arterial stiffening. The velocity waveform analysis of the retinal artery with DOCT flowmeter potentially could become a new method for arterial stiffness identification. Translational Relevance: DOCT flowmeter could evaluate arterial stiffening in a different way from the conventional method of measuring arterial stiffening using pressure waveform. Because the DOCT flowmeter can easily, quickly, and noninvasively provide a retinal blood velocity waveform, this system could be useful as a routine medical examination for arterial stiffening.

Deterioration of Retinal Blood Flow Parameters in Branch Retinal Vein Occlusion Measured by Doppler Optical Coherence Tomography Flowmeter.

BACKGROUND: Doppler optical coherence tomography (DOCT) flowmeter can be used to measure retinal blood flow (RBF) parameters, including vessel diameter, blood velocity, and the absolute value of RBF within 2.0 s. We investigated the RBF parameters in eyes with branch retinal vein occlusion (BRVO) using a DOCT flowmeter. METHODS: Seventeen patients with unilateral BRVO were enrolled. All subjects underwent comprehensive ophthalmologic examinations. The RBF parameters were assessed from three veins, i.e., (1) an occluded vein, (2) a non-occluded vein in the BRVO eyes, and (3) an equivalent (superior or inferior) vein in the fellow eye (non-affected vein), using prototype DOCT flowmeter (Topcon, Tokyo, Japan). Moreover, the correlation between RBF parameters and the best corrected visual acuity (BCVA) was examined. We investigated the correlation between (1) the RBF parameters and the time from the initial visit, (2) the RBF parameters and the time from the last injection, and (3) the RBF parameters and the number of anti-vascular endothelial growth factor injections (VEGF). RESULTS: The diameter of the occluded vein (95.9 ± 24.7 µm) was smaller than that of the non-occluded vein (127.9 ± 23.7 µm) and that of the healthy veins (116.4 ± 13.9 µm). The RBF was lower in the occluded veins (4.7 ± 3.7 µL/min) than that in the non-occluded veins (10.3 ± 5.1 µL/min; p < 0.01) and in the fellow eyes (8.6 ± 4.0 µL/min; p = 0.013). In contrast, the blood velocity was not significantly different among the three types of veins. BCVA was correlated with the diameter of the occluded vein (ρ = 0.711, p = 0.001) but not with the RBF and blood velocity. The time from the initial visit, the time from the last injection, and the total number of anti-VEGF injections were not associated with any RBF parameters on the occluded vein. CONCLUSIONS: The RBF was significantly lower in the occluded veins than that in the other veins, and the diameter of the occluded vein was significantly smaller than that of the other veins in patients with BRVO. However, neither the time from the initial visit, nor the time from the last injection, nor the number of anti-VEGF injections were correlated with the RBF parameters on the occluded vein.

Longitudinal Changes in Retinal Blood Flow in a Feline Retinal Vein Occlusion Model as Measured by Doppler Optical Coherence Tomography and Optical Coherence Tomography Angiography.

Purpose: We aimed to observe longitudinal changes in retinal blood flow (RBF) and structural transformations in capillaries using Doppler optical coherence tomography (DOCT) and optical coherence tomography angiography (OCTA) in a feline retinal blood occlusion (RVO) model. Methods: RVO was induced by argon green laser photocoagulation (PC) in six eyes of six cats. RBF was measured at a first-order retinal artery and vein by a DOCT flowmeter, and structural changes in the capillaries around the occluded vessels (12 × 12 and 3 × 3 mm) were assessed by OCTA before (at baseline); immediately after PC; and on days 1, 4, 7, and 14 thereafter. Systemic and ocular parameters were monitored during the observation period. Results: There were no significant differences in any systemic or ocular parameters before and after PC. Arterial RBF increased significantly on day 1 (160.6 ± 8.6% vs. baseline, P < 0.001) and decreased below baseline after day 1 through 14. Venous RBF decreased immediately after PC (17.4 ± 9.6% vs. baseline, P = 0.001) and then gradually increased afterwards, but did not return to baseline. OCTA showed dilatation of retinal venules immediately after PC to day 1. Collateral vessels began to form on day 4, had matured by day 7, and were pruned on day 14, which formed as mature as normal retinal venule diameters. Conclusions: With increasing arterial RBF within 1 day after inducing RVO, venules gradually expanded to form collateral vessels, suggesting that collateral vessels originate from existing capillary networks, not neovascularization.