Chorio-retinal vessel density in women affected by functional hypothalamic amenorrhea: a monocentric observational cross-sectional study to evaluate the impact of hypoestrogenism on chorio-retinal vascularization.

PURPOSE: Functional hypothalamic amenorrhea (FHA) is characterized by an estrogen deficiency which in turn can cause vascular dysfunction. The aim of this study is to evaluate any changes in the chorio-retinal circulation in patients affected by FHA. 24 patients with FHA and 24 age-matched controls underwent a gynecological evaluation and an OCT angiography (OCTA) to study chorio-retinal vascularization. RESULTS: OCTA in FHA patients showed an increase in vessel density in the choriocapillaris (CC) layer (both in the fovea area, at 5% p value = 0.037 and in the whole area, at 5% p value = 0.028) and an increase in vascular density in the deep fovea (DVP) (at 10% p value = 0.096) in the whole district compared to controls. Simple linear regressions show a significant negative association between CC vessel density and insulin (p = 0.0002) and glucose values (p = 0.0335) for the fovea district and a negative association between DVP vessel density and endometrial thickness (at 10%, p value: 0.095) in the whole district. CONCLUSION: Our study shows that CC vessel density is increased in women affected by FHA. This could represent a compensation effort to supply the vascular dysfunction caused by estrogen deficiency. We also found an increasing trend in vascular density in DVP associated with the decrease of endometrial thickness, an indirect sign of estrogenization. Considering that these changes occur in absence of visual defects, they could be used as a biomarker to estimate hypoestrogenism-induced microcirculation changes before clinical appearance.

Changes in retinal circulation and choroidal thickness in patients with acute myeloid leukemia detected by optical coherence tomography angiography.

Purpose: To investigate changes in retinal circulation and the choroid in patients with acute myeloid leukemia (AML) in the acute and remission stages, to analyze the correlation between retinal circulation and laboratory parameters, and to assess risk factors associated with leukemic retinopathy. Methods: Forty-eight patients (93 eyes) with AML were enrolled and divided into two groups according to fundus examination findings: the retinopathy and no retinopathy groups. Patients underwent eye measurements before treatment and after remission. Macular vessel density (VD), perfusion density (PD), foveal avascular zone (FAZ), and choroidal thickness (ChT) were measured using optical coherence tomography angiography. Patients with healthy eyes were recruited as control participants. Results: Patients with leukemic retinopathy had higher measurements of white blood cells (WBCs), circulating blasts, fibrin degradation products, and cross-linked fibrin degradation products (D-dimer) and a lower hemoglobin (HB) count (p < 0.05). In the acute phase of the disease, the VD and PD were lower and the ChT was thicker in patients with AML than in controls (p < 0.05), irrespective of the presence of leukemic retinopathy; however, the patients were partially recovered in the remission stage. The VD was lower in patients with higher WBC (r = -0.217, p = 0.036), D-dimer (r = -0.279, p = 0.001), fasting blood glucose (FBG) (r = -0.298, p = 0.004) and triglyceride (r = -0.336, p = 0.001) levels. The FAZ area was negatively correlated with HB (r = -0.258, p = 0.012). Conclusion: Patients with AML appear to have subclinical retinal perfusion loss and choroidal thickening in the acute phase of the disease, but this is reversible. Injury to bone marrow function may cause a decrease in retinal perfusion. Leukemic retinopathy is associated with abnormal hematologic parameters and coagulopathy.

Changes in Macular Thickness after Cataract Surgery in Patients with Open Angle Glaucoma.

BACKGROUND: The purpose of this study was to examine the changes in IOP, total macular and RNFL, ganglion cell layer (GCL) thickness, and aqueous humour flare in open angle glaucoma (OAG) patients before and 6 months after cataract surgery. METHODS: This was a prospective observational case-control age- and gender-matched study. Groups: 40 subjects in a controlled OAG (OAGc) group, 20 subjects in an uncontrolled OAG (OAGu) group, and 60 control group subjects. EXAMINATION: complete ophthalmic evaluation, IOP measurement, anterior and posterior segment Optical Coherence Tomography (OCT), and laser flare photometry before and 6 months postoperatively. RESULTS: Six months postoperatively IOP decreased in all groups. An increase in macular thickness was found postoperatively in all groups. Preoperative aqueous humour flare was higher in the OAGc group than in the control group. After cataract surgery, aqueous humour flare was higher in the control group compared to the preoperative result. CONCLUSIONS: Changes in IOP following cataract surgery were strongly negatively correlated with preoperative IOP. An increase in macular thickness was observed 6 months postoperatively in all groups. Aqueous humour flare did not differ in OAGc and OAGu groups pre- and postoperatively but significantly increased in the control group postoperatively.

Retinal microvascular function predicts chronic kidney disease in patients with cardiovascular risk factors.

BACKGROUND AND AIMS: Endothelial dysfunction is a precursor to atherosclerosis and is implicated in the coexistence between cardiovascular disease (CVD) and chronic kidney disease (CKD). We examined whether retinal microvascular dysfunction is present in subjects with renal impairment and predictive of long-term CKD progression in patients with CVD. METHODS: In a single centre prospective observational study, 253 subjects with coronary artery disease and CVD risk factors underwent dynamic retinal vessel analysis. Retinal microvascular dysfunction was quantified by measuring retinal arteriolar and venular dilatation in response to flicker light stimulation. Serial renal function assessment was performed over a median period of 9.3 years using estimated GFR (eGFR). RESULTS: Flicker light-induced retinal arteriolar dilatation (FI-RAD) was attenuated in patients with baseline eGFR <90 mL/min/1.73 m2, compared to those with normal renal function (eGFR ≥90 mL/min/1.73 m2) (1.0 [0.4-2.1]% vs. 2.0 [0.8-3.6]%; p < 0.01). In patients with normal renal function, subjects with the lowest FI-RAD responses exhibited the greatest annual decline in eGFR. In uni- and multivariable analysis, among subjects with normal renal function, a 1% decrease in FI-RAD was associated with an accelerated decline in eGFR of 0.10 (0.01, 0.15; p = 0.03) and 0.07 mL/min/1.73 m2 per year (0.00, 0.14; p = 0.06), respectively. FI-RAD was not predictive of CKD progression in subjects with baseline eGFR <90 mL/min/1.73 m2. CONCLUSIONS: Retinal arteriolar endothelial dysfunction is present in patients with CVD who have early-stage CKD, and serves as an indicator of long-term CKD progression in those with normal renal function.

Relationship between the macular retina vascular density and retinal circulation time in CRAO patients / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To observe the macular retina vascular density of patients with acute central retinal artery occlusion(CRAO)by optical coherence tomography angiography(OCTA)and to analyze the relationship with retinal circulation time of these patients on fundus fluorescein angiography(FFA).METHODS: Retrospective case analysis. A total of 43 patients(43 eyes)from January 2019 to March 2021 admitted to Shaanxi Eye Hospital with clinical diagnosis of acute CRAO(course of disease ≤7d)were included. All patients underwent FFA, OCTA, best corrected visual acuity(BCVA)examination and thrombolytic therapy. The patients with enhanced or unchanged retinal blood flow signal in the affected eye showed on OCTA before treatment compared with the contralateral healthy eye were assigned to group A, and the patients with retinal blood flow signal of the affected eye was lower than that in the contralateral healthy eye by OCTA were assigned to group B. Image J software was used for OCTA image processing to evaluate the macular retina vascular density before treatment, and FFA examination was performed to record the affected retinal circulation time before treatment.RESULTS: The retinal vascular density of patients in the affected eye and the contralateral healthy eye in group A was higher than that in group B(25.08%±4.40% vs 12.24%±3.41%, 25.72%±2.70% vs 17.89%±4.55%, all P&#x003C;0.001), the filling time(FT)of retinal artery trunk to terminal in group B [96(20.50, 193.50)s] was longer than that in group A [11(5.00, 19.50)s](P&#x003C;0.001). The course of disease, the retinal vascular density of contralateral healthy eye and FT were related factors of retinal vascular density of the affected eye(all P&#x003C;0.05), and the influence strength order was FT, course of disease and the retinal vascular density of contralateral healthy eye, in which the course of disease and FT was negatively correlated with the retinal vascular density.CONCLUSION: OCTA retinal vascular density was correlated with FFA retinal circulation time in CRAO patients.

Minireview: Insights into the role of TRP channels in the retinal circulation and function.

Consistent with their wide distribution throughout the CNS, transcripts of all transient receptor potential (TRP) cation channel superfamily members have been detected in both neuronal and non-neuronal cells of the mammalian retina. Evidence shows that members of the TRPC (canonical, TRPC1/4/5/6), TRPV (vanilloid, TRPV1/2/4), TRPM (melastatin, TRPM1/2/3/5), TRPA (ankyrin, TRPA1), and TRPP (polycystin, TRPP2) subfamilies contribute to retinal function and circulation in health and disease, but the relevance of most TRPs has yet to be determined. Their principal role in light detection is far better understood than their participation in the control of intraocular pressure, retinal blood flow, oxidative stress, ion homeostasis, and transmitter signaling for retinal information processing. Moreover, if the therapeutic potential of targeting some TRPs to treat various retinal diseases remains speculative, recent studies highlight that vision restoration strategies are very likely to benefit from the thermo- and mechanosensitive properties of TRPs. This minireview focuses on the evidence of the past 5 years about the role of TRPs in the retina and retinal circulation, raises some possibilities about the function of TRPs in the retina, and discusses the potential sources of endogenous stimuli for TRPs in this tissue, as a reflection for future studies.

L-Citrulline ameliorates the attenuation of acetylcholine-induced vasodilation of retinal arterioles in diabetic rats.

In our previous study, we found that the vasodilation of retinal arterioles induced by acetylcholine and BMS-191011, a large-conductance Ca2+-activated K+ (BKCa) channel opener, were diminished in diabetic rats. Currently, few agents ameliorate the impaired vasodilator responses of retinal blood vessels. Our recent finding that the intravenous infusion of L-citrulline dilated retinal arterioles, suggests that L-citrulline could be a potential therapeutic agent for circulatory disorders of the retina. In this study, we determined the effect of an oral L-citrulline treatment on impaired acetylcholine- and BMS-191011-induced vasodilation in the retinal arterioles of diabetic rats. To induce diabetes, rats were administered an intravenous dose of streptozotocin (65 mg/kg) and a 5% D-glucose solution as drinking water. The L-citrulline (2 g/kg/day) and L-arginine (2 g/kg/day) treatments commenced either 15 days before or just after the streptozotocin injection and continued throughout the experimental period. A 29-day treatment with L-citrulline, but not L-arginine, significantly ameliorated the impaired acetylcholine- and BMS-191011-induced retinal vasodilation in diabetic rats without affecting their plasma glucose levels. The 2-week L-citrulline treatment tended to ameliorate the dysfunction of the acetylcholine-induced retinal vasodilation in diabetic rats. In conclusion, these results showed that the retinal blood vessel dysfunction induced by diabetes mellitus could be prevented by the long-term administration of L-citrulline and suggest that the latter could play a potentially prophylactic role in diabetic retinopathy.

Impaired retinal microvascular function predicts long-term adverse events in patients with cardiovascular disease.

AIMS: Endothelial dysfunction is a precursor to the development of symptomatic atherosclerosis. Retinal microvascular reactivity to flicker light stimulation is a marker of endothelial function and can be quantified in vivo. We sought to determine whether retinal microvascular endothelial dysfunction predicts long-term major adverse cardiovascular events (MACE). METHODS AND RESULTS: In a single-centre prospective observational study, patients with coronary artery disease (CAD) or cardiovascular risk factors underwent dynamic retinal vessel assessment in response to flicker light stimulation and were followed up for MACE. Retinal microvascular endothelial dysfunction was quantified by measuring maximum flicker light-induced retinal arteriolar dilatation (FI-RAD) and flicker light-induced retinal venular dilatation (FI-RVD). In total, 252 patients underwent dynamic retinal vessel assessment and 242 (96%) had long-term follow-up. Of the 242 patients, 88 (36%) developed MACE over a median period of 8.6 years (interquartile range 6.0-9.1). After adjustment for traditional risk factors, patients within the lowest quintile of FI-RAD had the highest risk of MACE [odds ratio (OR) 5.21; 95% confidence interval (CI) 1.78-15.28]. Patients with lower FI-RAD were also more likely to die (OR 2.09; 95% CI 1.00-4.40, per standard deviation decrease in FI-RAD). In Kaplan-Meier analysis, patients with FI-RAD responses below the cohort median of 1.4% exhibited reduced MACE-free survival (55.5 vs. 71.5%; log-rank P = 0.004). FI-RVD was not predictive of MACE. CONCLUSION: Retinal arteriolar endothelial dysfunction is an independent predictor of MACE in patients with CAD or cardiovascular risk factors. Dynamic retinal vessel analysis may provide added benefit to traditional risk factors in stratifying patients at risk for cardiovascular events.

Artery-venous classification in fluorescein angiograms based on region growing with sequential and structural features.

BACKGROUND AND OBJECTIVES: Fluorescein angiography (FA) is widely used in ophthalmology for examining retinal hemodynamics and vascular morphology. Artery-venous classification is an important step in FA image processing for measurement of feature parameters, such as arterio-venous passage time (AVP) and arterio-venous width ratio (AVR) that are proven useful in clinical assessment of circulation disturbance and vessel abnormalities. However, manual artery-venous classification needs expertise and is rather time consuming, and little effort has been devoted to develop automatic classification methods. In order to solve this problem, we propose a novel artery-venous classification method using region growing strategy with sequential and structural features (RGSS). METHODS: The main procedures of our proposed RGSS method include: (i) registration of FA image sequence by mutual-information method; (ii) extraction of sequential features of the dye perfusion process from the registrated FA images; (iii) extraction of vessel structural features from vascular centerline map; (iv) based on the obtained features, seeds of arteries and veins within initial growing region (here optic disk) are generated and then propagated in the entire vessel network using region growing strategy. The RGSS method was tested on our own dataset and public Duke dataset, and its performance was evaluated quantitatively. RESULTS: Tests show that RGSS method is able to classify arteries and veins from the complicated vessel network in FA images, with high classification accuracy of 0.91 ± 0.04 on Duke dataset and 0.92 ± 0.03 on our dataset. The employed sequential and structural features are demonstrated to be effective in classifying thin arteries and veins at vessel crossings. CONCLUSIONS: Automatic artery-venous classification can be accomplished using our proposed RGSS method with high accuracy. The RGSS method not only emancipates ophthalmologists from hard work of manual marking of arteries and veins, but also helps in measuring important parameters (such as AVP and AVR) for clinical assessment of circulation disturbance and vessel abnormalities.

Impaired Retinal Circulation during Axitinib Treatment for Metastatic Renal Cell Carcinoma.

PURPOSE: Axitinib, an orally administered vascular endothelial growth factor receptors 1, 2, and 3 inhibitor, is widely used as the second-line treatment for metastatic renal cell carcinoma. We present a case of metastatic renal cell carcinoma who developed a novel ocular adverse event, impaired retinal circulation, during axitinib therapy. METHODS: This is an observational case report. RESULTS: A 57-year-old male who had been treated with axitinib for metastatic renal cell carcinoma for 2 years presented in August 2015. He complained of sudden-onset abnormal visual field in his right eye. His right eye exhibited multiple soft exudates on fundus photography and a significant fluorescein filling delay of the retinal vessels on fluorescein angiography. His best corrected visual acuity (BCVA) was 20/20 in the right eye, and a cecocentral scotoma was detected by Goldmann perimeter. As axitinib could have been responsible for impaired retinal circulation, axitinib was terminated and switched to temsirolimus. The soft exudates gradually subsided and the patients' symptoms got better, but his right BCVA dropped to 20/63 3 months after the end of axitinib treatment with worsening of his general condition. CONCLUSION: Clinicians should be aware of retinal circulatory disorder that can occur in patients under axitinib treatment.

Retinal vascular tortuosity assessment: inter-intra expert analysis and correlation with computational measurements.

BACKGROUND: The retinal vascular tortuosity can be a potential indicator of relevant vascular and non-vascular diseases. However, the lack of a precise and standard guide for the tortuosity evaluation hinders its use for diagnostic and treatment purposes. This work aims to advance in the standardization of the retinal vascular tortuosity as a clinical biomarker with diagnostic potential, allowing, thereby, the validation of objective computational measurements on the basis of the entire spectrum of the expert knowledge. METHODS: This paper describes a multi-expert validation process of the computational vascular tortuosity measurements of reference. A group of five experts, covering the different clinical profiles of an ophthalmological service, and a four-grade scale from non-tortuous to severe tortuosity as well as non-tortuous / tortuous and asymptomatic / symptomatic binary classifications are considered for the analysis of the the multi-expert validation procedure. The specialists rating process comprises two rounds involving all the experts and a joint round to establish consensual rates. The expert agreement is analyzed throughout the rating procedure and, then, the consensual rates are set as the reference to validate the prognostic performance of four computational tortuosity metrics of reference. RESULTS: The Kappa indexes for the intra-rater agreement analysis were obtained between 0.35 and 0.83 whereas for the inter-rater agreement in the asymptomatic / symptomatic classification were between 0.22 and 0.76. The Area Under the Curve (AUC) for each expert against the consensual rates were placed between 0.61 and 0.83 whereas the prognostic performance of the best objective tortuosity metric was 0.80. CONCLUSIONS: There is a high inter and intra-rater variability, especially for the case of the four grade scale. The prognostic performance of the tortuosity measurements is close to the experts' performance, especially for Grisan measurement. However, there is a gap between the automatic effectiveness and the expert perception given the lack of clinical criteria in the computational measurements.

Automatic measurement of global retinal circulation in fluorescein angiography.

Examination of the retinal circulation in patients with retinal diseases is a clinical routine for ophthalmologists. In the present work, an automatic method is proposed for measuring the global retinal circulation in fluorescein angiography (FA). First, the perfusion region in FA images is segmented using a multiscale line detector. Then, the time evolution of the perfusion area is modeled using damped least-squares regression. Based on the perfusion area profile, some circulation parameters are defined to describe quantitatively the global retinal circulation. The effectiveness of the proposed method is tested using our own and public datasets, with reasonable results and satisfactory accuracy compared with manual measurement. The proposed method has good computing efficiency and thus has potential to be used in clinical practice for evaluation of global retinal circulation.

Quantitative comparisons between optical coherence tomography angiography and matched histology in the human eye.

The aim was to quantitatively compare retinal vascular detail as seen on optical coherence tomography angiography (OCTA) and matched histology in the human eye. 13 normal human donor eyes were used. The central retinal artery was cannulated after which human packed red blood cells were perfused through the retinal vasculature. Retinal vessels were imaged using a custom-built OCTA device during red blood cell perfusion. The eye was subsequently perfused with endothelial cell antibodies and the flat-mounted retina studied histologically using a confocal scanning laser microscope. Qualitative and quantitative comparisons of retinal vascular information as seen on OCTA and histology from the same region of interest were performed. Gradable OCTA images were acquired from 4 of 13 eyes with mean postmortem-to-OCTA imaging time of 4.5 ±â€¯1.3 h 23 pairs of OCTA-histology matched images were evaluated. The retinal arteries and veins had similar pixel intensity on OCTA images. The diameter of retinal veins was significantly greater than its paired artery on OCTA (P < 0.001). The density of vascular structures on OCTA (40.2% ±â€¯10.1%) was significantly less than matched histology (52.1% ±â€¯9.3%, P < 0.001). Mean capillary diameter on OCTA (10.2 ±â€¯2.4 µm) was significantly greater than histology (8.2 ±â€¯2.4 µm; P < 0.001). This is the first study to directly compare OCTA against histology from the same human eye. OCTA visualizes many of the vascular structures in the human retinal circulation but does not exactly match what is seen on histologic examination.

Central retinal artery occlusion during vitrectomy: Immediate retinal revascularization following induction of posterior vitreous detachment.

PURPOSE: To describe a patient with acute central retinal artery occlusion (CRAO) during vitrectomy surgery and the possible role of vitrectomy in acute CRAO management. OBSERVATIONS: An 84-year-old man presented with broad vitreomacular traction and epiretinal membrane in the right eye. Preoperative assessment clearly showed normal retinal vasculature. On starting vitrectomy, complete CRAO with marked segmentation of all retinal vessels was noted. Vitrectomy was performed in the usual manner and once the posterior hyaloid detached from the disc, immediate complete revascularization of the retinal vessels was noted. The patient had a complete visual recovery. CONCLUSIONS AND IMPORTANCE: Immediate vitrectomy with induction of posterior vitreous detachment may have a role in selected cases of acute CRAO, particularly if performed within a short window.

Hypoxia challenge test and retinal circulation changes - a study using ocular coherence tomography angiography.

PURPOSE: Previous studies report that the response of retinal vessels to a decrease in oxygen (hypoxia) is vasodilation, thus increasing blood flow. We aimed to characterize the changes in retinal microvasculature induced by a mild hypoxia stress test in a healthy population, using ocular coherence tomography angiography (OCT-A) technology. METHODS: Interventional repeated-measures study. The standardized hypoxia challenge test (HCT) was performed to all volunteers, according to the British Thoracic Society protocol. Ocular coherence tomography angiography (OCT-A) was performed at three time-points (baseline, during HCT and 30' posthypoxia). Macular and peripapillary vessel densities were assessed using the built-in software. To minimize bias, analysis was performed separately in right (OD) and left (OS) eyes. Repeated-measures anova and mean comparison analysis were used as statistical tests (stata v13). RESULTS: Studied population included 30 healthy subjects (14 women), with a mean age of 28.8 ± 4.2 [range 22-37] years. Baseline vessel density increased in hypoxic conditions and subsequently decreased to near-baseline values in posthypoxia conditions. This pattern was observed for both eyes in both parafovea (OD: 55.3 ± 2.3 to 56.7 ± 1.9 to 55.8 ± 1.9, p < 0.05; OS: 56.9 ± 2.1 to 57.9 ± 1.9 to 57.3 ± 1.7, p < 0.05) and peripapillary (OD: 60.5 ± 0.5 to 62.6 ± 0.5 to 60.1 ± 0.4, p < 0.05; OS: 60.4 ± 0.4 to 62.3 ± 0.5 to 60.7 ± 0.4, p < 0.05) areas. CONCLUSION: To our knowledge, there are no published data specifically addressing mild hypoxia conditions and retinal microvasculature changes, using OCT-A. This pilot study may pave way to better understand vascular responses in disease setting.

Probucol prevents the attenuation of ß2-adrenoceptor-mediated vasodilation of retinal arterioles in diabetic rats.

Probucol is an antihyperlipidemic drug with potent antioxidant properties. Oxidative stress plays an important role in the pathogenesis of diabetic retinopathy. In this study, we aimed to investigate the protective effects of probucol against diabetes-induced retinal vascular dysfunction in a rat model of diabetes. Diabetes was induced by a combination of streptozotocin treatment and D-glucose feeding, and retinal vasodilator responses were assessed by measuring the diameter of retinal arterioles. The vasodilator effect of salbutamol, a ß2-adrenoceptor agonist, on retinal arterioles was significantly diminished 2 weeks after the induction of diabetes. In non-diabetic rats, vasodilator responses to salbutamol were significantly reduced after an intravitreal injection of iberiotoxin, a blocker of large-conductance KCa (BKCa) channels. However, this effect was not observed in diabetic rats. Probucol had no significant effect on salbutamol-induced changes in diameter of retinal arterioles in non-diabetic rats, whereas it could prevent the attenuation of retinal vasodilator response to salbutamol in diabetic rats. These results suggest that the reduced function of BKCa channels is involved in the attenuation of ß2-adrenoceptor-mediated retinal vasodilation in diabetic rats. Probucol preserves the BKCa channel function in retinal arterioles under diabetic conditions; therefore, it may show beneficial effects on diabetic retinopathy by preventing or slowing the impairment of the retinal circulation in patients with diabetes mellitus.

Stimulation of ß1- and ß2-adrenoceptors dilates retinal blood vessels in rats.

Our previous studies have demonstrated that adrenaline dilates rat retinal arterioles by stimulating propranolol-sensitive ß-adrenoceptors and ß3-adrenoceptors, and selective stimulation of ß2- or ß3-adrenoceptors causes retinal vasodilator responses. In the present study, we compared the effects of ß1- and ß2-adrenoceptor stimulation on rat retinal arterioles in vivo. Rat ocular fundus images were captured using an original high-resolution digital fundus camera. Diameters of retinal arterioles contained in the images were measured. Systemic blood pressure and heart rate were recorded continuously. Denopamine, a ß1-adrenoceptor agonist, increased the diameter of retinal arterioles and heart rate, and produced a small but statistically insignificant decrease in mean arterial pressure. CGP20712A, a ß1-adrenoceptor antagonist, but not ICI118551, a ß2-adrenoceptor antagonist, significantly prevented denopamine-induced retinal vasodilator and heart rate responses. Salbutamol, a ß2-adrenoceptor agonist, increased the diameter of retinal arterioles and decreased mean arterial pressure without significantly changing heart rate. The effects of salbutamol were significantly prevented by ICI118551, but not by CGP20712A. These results suggest that stimulation of ß1- and ß2-adrenoceptors dilates retinal blood vessels and indicate that all three ß-adrenoceptor subtypes (ß1, ß2, and ß3) may be involved in the retinal vasodilator response to adrenaline in rats.

Changes of retinal circulation time before and after panretinal laser photocoagulation in patients with diabetic retinopathy / 眼科新进展

Objective To observe the changes of preoperative and postoperative retinal circulation time in partretinal laser photocoagulation (PRP) in patients with diabetic retinopathy (DR).Methods Together 16 patients (16 eyes) were collected as the subjects in this study,who was diagnosed as severe non-proliferative and proliferative DR by fundus fluorescein angiography (FFA) examination and had PRP indications for undergoing pan-retinal laser photocoagulation.Then retinal arterial and venous cir culation time in all patients was recorded using FFA before and 1 to 3 months after treatment.Meanwhile,it was necessary to observe the following variables,including the developing duration and complete filling time of the four branches of the retinal artery,as well as the duration of the laminar flow and complete filling time of the four branches of the venous artery,followed by calculating mean transition time of retinal artery,retinal capillary,retinal vein,retinal arteriovenous flow for comparison and analysis of changes in transit time of retina in different time-periods before and after treatment.Results The mean transition time of the retinal capillary in patient was (1.58 ± 0.99) s before treatment and (2.19 + 1.23)s after treatment,and the difference was statistically significant(P =0.011),but there was no significant difference in the mean transition time of the retinal artery,retinal vein and arteriovenous flow (all P ＞ 0.05).Conclusion The transit time of the retinal capillary at 1 to 3 months after PRP is significantly longer than that before treatment.

Changes of retinal circulation time before and after panretinal laser photocoagulation in patients with diabetic retinopathy / 眼科新进展

Objective To observe the changes of preoperative and postoperative retinal circulation time in partretinal laser photocoagulation (PRP) in patients with diabetic retinopathy (DR).Methods Together 16 patients (16 eyes) were collected as the subjects in this study,who was diagnosed as severe non-proliferative and proliferative DR by fundus fluorescein angiography (FFA) examination and had PRP indications for undergoing pan-retinal laser photocoagulation.Then retinal arterial and venous cir culation time in all patients was recorded using FFA before and 1 to 3 months after treatment.Meanwhile,it was necessary to observe the following variables,including the developing duration and complete filling time of the four branches of the retinal artery,as well as the duration of the laminar flow and complete filling time of the four branches of the venous artery,followed by calculating mean transition time of retinal artery,retinal capillary,retinal vein,retinal arteriovenous flow for comparison and analysis of changes in transit time of retina in different time-periods before and after treatment.Results The mean transition time of the retinal capillary in patient was (1.58 ± 0.99) s before treatment and (2.19 + 1.23)s after treatment,and the difference was statistically significant(P =0.011),but there was no significant difference in the mean transition time of the retinal artery,retinal vein and arteriovenous flow (all P ＞ 0.05).Conclusion The transit time of the retinal capillary at 1 to 3 months after PRP is significantly longer than that before treatment.

Visible light optical coherence tomography measures retinal oxygen metabolic response to systemic oxygenation.

The lack of capability to quantify oxygen metabolism noninvasively impedes both fundamental investigation and clinical diagnosis of a wide spectrum of diseases including all the major blinding diseases such as age-related macular degeneration, diabetic retinopathy, and glaucoma. Using visible light optical coherence tomography (vis-OCT), we demonstrated accurate and robust measurement of retinal oxygen metabolic rate (rMRO2) noninvasively in rat eyes. We continuously monitored the regulatory response of oxygen consumption to a progressive hypoxic challenge. We found that both oxygen delivery, and rMRO2 increased from the highly regulated retinal circulation (RC) under hypoxia, by 0.28 ± 0.08 µL min-1 (p < 0.001), and 0.20 ± 0.04 µL min-1 (p < 0.001) per 100 mmHg systemic pO2 reduction, respectively. The increased oxygen extraction compensated for the deficient oxygen supply from the poorly regulated choroidal circulation. Results from an oxygen diffusion model based on previous oxygen electrode measurements corroborated our in vivo observations. We believe that vis-OCT has the potential to reveal the fundamental role of oxygen metabolism in various retinal diseases.