- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Evaluation of blood flow on optic nerve head after pattern scan and conventional laser panretinal photocoagulation
摘要： To evaluate the changes in the blood ?ow on retina and the optic nerve head (ONH) after conventional laser treatment and to compare it to that after patterned scanning laser (PASCAL) treatment in patients with severe nonproliferative diabetic retinopathy (S-NPDR). In this prospective, cross-sectional study, the blood ?ow on retina and the ONH was assessed by laser speckle ?owgraphy using the mean blur rate (MBR) in 39 eyes with S-NPDR before, 1, 4, 8, 12 weeks after panretinal photocoagulation (PRP). Of 39 eyes, 17eyes with 17 patients treated by conventional laser and 22 eyes with 22 patients treated by PASCAL. The mean age was 55.5 ± 11.5 years in the conventional laser group, 55.6 ± 11.8 years in the PASCAL group. The MBR-vessel, which can be dominantly expressed as retinal blood ?ow, was signi?cantly reduced after PRP treated by conventional laser (P < .001), but did not change after PRP treated by PASCAL. The ratio of MBR-vessel to the baseline was signi?cantly lower in the conventional laser group only at Week 1 (P = .045). The MBR-tissue, which can be dominantly expressed as the ONH blood ?ow, did not signi?cantly change after PRP in the both group. The multiple stepwise regression analysis revealed that the laser burns was an independent factor signi?cantly correlated with the ratio of MBR-vessel at Week 1 to the baseline (b = (cid:1)0.550, P = .012). The retinal blood ?ow was signi?cantly reduced during the 12 weeks only after completion of PRP by conventional laser treatment. Our results indicate that short pulse on PRP treatment performed by the PASCAL would not signi?cantly reduce the retinal blood ?ow.
关键词： laser speckle ?owgraphy,patterned scanning laser,panretinal photocoagulation,mean blur rate,retinal blood ?ow
更新于2025-09-12 10:27:22
-
Retinal Blood Flow Response to Hyperoxia Measured With En Face Doppler Optical Coherence Tomography
摘要： PURPOSE. To use multiplane en face Doppler optical coherence tomography (OCT) to measure the change in total retinal blood ?ow (TRBF) in response to hyperoxia. METHODS. One eye of each healthy human participant (n ? 8) was scanned with a commercial high-speed (70-kHz) spectral OCT system. Three repeated scans were captured at baseline and after 10 minutes of oxygen (hyperoxia) by open nasal mask. The procedure was performed twice on day 1 and once more on day 2. Blood ?ow of each vein was estimated using Doppler OCT at an optimized en face plane. The TRBF was summed from all veins at the optic disc. The TRBF hyperoxic response was calculated as the TRBF percent change from baseline. RESULTS. Participants experienced a 23.6% 6 10.7% (mean 6 standard deviation [SD]) decrease (P < 0.001, paired t-test) in TRBF during hyperoxia. The within-day repeatability of baseline TRBF was 4.1% and the between-day reproducibility was 10.9% coef?cient of variation (CV). Between-grader reproducibility was 3.9% CV. The repeatability and reproducibility (pooled SD) of hyperoxic response were 6.1% and 6.4%, respectively. CONCLUSIONS. The multiplane en face Doppler OCT algorithm was able to detect, in all participants, a decreased TRBF in response to hyperoxia. The response magnitude for each participant varied among repeated trials, and the averaging of multiple trials was helpful in establishing the individual response. This technique shows good potential for the clinical investigation of vascular autoregulation.
关键词： hyperoxia,en face doppler optical coherence tomography,total retinal blood ?ow
更新于2025-09-10 09:29:36
-
Total Retinal Blood Flow in a Nonhuman Primate Optic Nerve Transection Model Using Dual-Beam Bidirectional Doppler FD-OCT and Microsphere Method
摘要： PURPOSE. We validated noninvasive Doppler-optical coherence tomography (OCT) blood ?ow measurements against the terminal microsphere method in a surgical induced optic nerve transection nonhuman primate model. METHODS. In 6 nonhuman primates, total retinal blood ?ow (TRBF) was measured with a custom-built dual-beam bidirectional Doppler Fourier Domain (FD)-OCT. Peripapillary retinal nerve ?ber layer thickness (RNFLT) was measured by Spectralis spectral-domain (SD)-OCT. Measurements were performed every 10 to 15 days before and after unilateral optic nerve transection (ONT) until RNFLT was reduced by more than 40% from baseline. Before the animals were killed, TRBF was measured using the microsphere technique. RESULTS. A signi?cant correlation between all arterial and venous Doppler OCT TRBF measurements was found in ONT and contralateral control eyes (both P < 0.01, n ? 6). The Bland-Altman analysis showed a bias of 0.57 in the ONT group and 0.02 in the contralateral control group. Also, excellent agreement was observed between Doppler OCT and microsphere measurements (P < 0.01, r ? 0.976, bias ? 0.54). After ONT, TRBF and RNFLT decreased by (cid:2)51% 6 42% and (cid:2)44% 6 2% (n ? 5), respectively. In the contralateral control eyes, TRBF and RNFLT were unchanged. CONCLUSIONS. Very good accordance was found between TRBF measurements, obtained with dual-beam bidirectional Doppler FD-OCT and the microsphere method. It also was possible to monitor changes over time in TRBF after ONT with Doppler OCT. These ?ndings highlight the accuracy and potential of noninvasive Doppler OCT to provide valuable information for detecting early changes in ocular disease in future.
关键词： microspheres,optic nerve transection,total retinal blood ?ow,Doppler OCT,nonhuman primate
更新于2025-09-09 09:28:46
-
Histamine-Induced Dilation of Isolated Porcine Retinal Arterioles: Role of Endothelium-Derived Hyperpolarizing Factor
摘要： PURPOSE. Although endothelium-dependent nitric oxide (NO)–mediated dilation of retinal arterioles has been well described, the role of endothelium-derived hyperpolarizing factor (EDHF) in the retinal arteriolar response remains unclear. In the current study, we examined the contribution of EDHF to the retinal arteriolar dilation to the in?ammatory agent histamine and investigated the signaling mechanisms underlying this vasomotor activity. METHODS. Porcine retinal arterioles were isolated, cannulated, and pressurized without ?ow for functional study by using video microscopic techniques. The immunohistochemical staining was performed to determine histamine receptor subtypes. RESULTS. Histamine (0.1–30 lM) produced concentration-dependent dilation of retinal arterioles in a manner sensitive to H1- and H2-receptor antagonists chlorpheniramine and famotidine, respectively. Histamine-induced vasodilation was almost abolished after endothelial removal. In the intact vessels, vasodilation to histamine was partially inhibited by the inhibitors of cyclooxygenase (indomethacin), NO synthase (NG-nitro-L-arginine methyl ester, L-NAME), or Ca2t -activated Kt (KCa) channels (apamin plus charybdotoxin). Combination of the above inhibitors abolished histamine-induced vasodilation. Residual vasodilation in the presence of indomethacin and L-NAME was further reduced by the cytochrome P450 enzyme inhibitor sulfaphenazole but not by the gap junction inhibitor carbenoxolone or the hydrogen peroxide scavenger catalase. Immunohistochemical signals for H1- and H2-receptor expression were found only in the endothelium. CONCLUSIONS. The endothelium plays an essential role in the dilation of porcine retinal arterioles to histamine via H1- and H2-receptor activation. The EDHF derived from cytochrome P450 contributed in part to this vasodilation via KCa channel activation, in addition to the endothelial release of NO and prostanoids.
关键词： arterioles,EDHF,retinal blood ?ow,endothelium,histamine
更新于2025-09-04 15:30:14