Ocular Circulation Research Articles

Differences in Systemic Pulse Waveform Between Individuals With Glaucoma, Glaucoma Suspects, and Healthy Controls.

It has been hypothesized that compromised ocular circulation in glaucoma may be concomitant of systemic changes. The purpose of this study is to test whether systemic blood flow pulse waveform patterns differ between individuals with glaucoma (GL), glaucoma suspects (GLS), and normal healthy controls (HC). The study included 35 bilateral GL, 67 bilateral GLS, 29 individuals with unilateral GL who were considered GLS in the other eye, and 44 healthy controls. Systemic pulsatile blood pressure waveforms were recorded using a finger cuff. A continuous 200Hz plethysmography recording is made to obtain a pulse waveform. Waveform parameters were extracted using custom software from an average of eight pulse cycles. These were compared between GL, GLS, and HC groups on a per-eye basis, using generalized estimating equation models to account for intereye correlations; and plotted against disease severity by visual field linearized mean deviation (MDlin) and retinal nerve fiber layer thickness (RNFLT). Averaged blood pressure was significantly lower in the HC group (mean ± standard deviation 91.7 ±11.7 mm Hg) than the GLS (102.4 ± 13.9) or GL (102.8 ± 13.7) groups, with P < 0.0001 (generalized estimating equation regression). Waveform parameters representing vascular resistance were higher in both GLS and GL groups than the HC group; and were correlated with RNFLT and MDlin (P ≤ 0.05). The shape of the systemic pulsatile waveform differs in individuals with GL/GLS suspects, compared to HC eyes. Blood pressure changes more rapidly in individuals with GL, which suggests higher arterial stiffness.

Superficial ocular vascular changes after orbital decompression in patients with thyroid ophthalmopathy measured by anterior segment OCT angiography; an observational study

Thyroid eye disease (TED) is a common ophthalmologic manifestation of thyroid dysfunction. Despite various imaging techniques available, there hasn't been a widely adopted method for assessing the anterior segment vasculature in TED patients. Our study aimed to evaluate alterations in ocular surface circulation following orbital decompression surgery in TED patients and investigate factors influencing these changes. Using anterior segment optical coherence tomography-angiography (AS-OCTA), we measured ocular surface vascularity features, including vessel density (VD), vessel diameter index (VDI), and vessel length density (VLD), both before and after decompression surgery, alongside standard ophthalmic examinations. Our AS-OCTA analysis revealed a significant decrease in most of the temporal vasculature measurements six weeks post-surgery (p < 0.05). However, differences in the nasal region were not statistically significant. These findings indicate notable changes in ocular surface circulation following orbital decompression in TED patients, which may have implications for intraocular pressure (IOP) control and ocular surface symptoms management. AS-OCTA holds promise as a tool for evaluating the effectiveness of decompression surgery and assessing the need for further interventions.

Effects and potential mechanisms of exercise and physical activity on eye health and ocular diseases.

In the field of eye health, the profound impact of exercise and physical activity on various ocular diseases has become a focal point of attention. This review summarizes and elucidates the positive effects of exercise and physical activities on common ocular diseases, including dry eye disease (DED), cataracts, myopia, glaucoma, diabetic retinopathy (DR), and age-related macular degeneration (AMD). It also catalogues and offers exercise recommendations based on the varying impacts that different types and intensities of physical activities may have on specific eye conditions. Beyond correlations, this review also compiles potential mechanisms through which exercise and physical activity beneficially affect eye health. From mitigating ocular oxidative stress and inflammatory responses, reducing intraocular pressure, enhancing mitochondrial function, to promoting ocular blood circulation and the release of protective factors, the complex biological effects triggered by exercise and physical activities reveal their substantial potential in preventing and even assisting in the treatment of ocular diseases. This review aims not only to foster awareness and appreciation for how exercise and physical activity can improve eye health but also to serve as a catalyst for further exploration into the specific mechanisms and key targets through which exercise impacts ocular health. Such inquiries are crucial for advancing innovative strategies for the treatment of eye diseases, thereby holding significant implications for the development of new therapeutic approaches.

Evaluating the relationship between ocular blood flow and systemic organ blood flow in hemorrhagic shock using a rabbit model

This study aimed to investigate the feasibility of utilizing noninvasive ocular blood flow measurements as potential indicators of systemic circulation in rabbits experiencing hemorrhagic shock. Using Laser speckle flowgraphy, ocular blood flow indices, relative flow volume (RFV), and mean blur rate in the choroidal area (MBR-CH) were assessed in New Zealand White rabbits (n = 10) subjected to controlled blood removal and return. Hemodynamic parameters and biochemical markers were monitored alongside ocular circulation during blood removal and return phases. Additionally, correlations between ocular parameters and systemic indices were examined. The results indicated that RFV and MBR-CH exhibited significant correlations with renal and intestinal blood flows, with stronger correlations observed during blood removal. Additionally, ocular blood flow changes closely mirrored systemic dynamics, suggesting their potential as real-time indicators of shock progression and recovery. These findings indicate that ocular blood flow measurements may serve as real-time indicators of the systemic circulation status during hemorrhagic shock, offering potential insights into shock management and guiding tailored interventions. Thus, noninvasive ocular blood flow evaluation holds promise as an innovative tool for assessing systemic circulation dynamics during hemorrhagic shock.

The effects of physical exercise on ocular blood flow

Vascular resistance is physiologically regulated by changing the local diameter of the arterioles to keep the local blood flow constant. It is well known that physical activity has profound impacts on the vasculature in humans. Short‐term exercise induces immediate changes in artery function, whereas long‐term exercise induces chronic functional adaptation and structural arterial remodelling which leads to a lower risk of risk for cardiovascular disease. These changes depended on the characteristics of the training load and are modulated by other factors such as exercise‐induced inflammation and oxidative stress.The ocular circulation consists of the retinal and choroidal circulations. The retina is the tissue with the most active metabolism in the human body, resulting in a high rate of oxygen consumption. Therefore, ocular blood flow is particularly susceptible to physical exercise. With the arrival of imaging technologies numerous studies have explored the effects of exercise on the ocular blood flow. Most of these studies are focused on the transient impact of acute exercise on ocular blood flow. The objective of this talk is to discuss the scientific literature available about the effects of physical exercise on ocular blood flow, and to highlight its impact on ocular health.

In Memoriam: Valerii Semenovych Ponomarchuk

In Memoriam: Valerii Semenovych Ponomarchuk

Evaluation of the Retina and Optic Discs of Patients with Chronic and Episodic Migraine using Optical Coherence Tomography and Optical Coherence Tomography Angiography

Objective: Migraine is a very common,recurring, usually unilateral, severe, pulsating, and transient headache disorder, which causes temporary disability. Migraine has two main types: with aura and without aura. Abnormal retinal and optic disc pathologies in migraine patients were previously reported by using optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). In the present study, it was suggested that the changes foundin the retina and optic disc mightindicate a functional disorder in chronic (with and without aura) and episodic (with and without aura) migraine. It is also emphasized that these changes might be useful for early diagnosis and follow-up of the disease, as well as for the development of new treatments. Method: In total, 60 individuals were involved in the present study, including 28 chronic migraine patients (24 female, 4 male, 16 with aura, 12 without aura) and 32 episodic migraine patients (26 female, 6 male, 21 with aura, 11 without aura), who were diagnosed with migraine and whose migraine types were determinedby using the criteria set by the International Headache Society (IHS) in 2013. The control group consisted of 48 healthy volunteers (34 female, 14 male) aged between 18 and 45 years, who applied to the ophthalmology clinic. The retinas and optic discs of the patients were examined by optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) at our ophthalmology clinic. A double-blind randomized analysis was performed for the patient data and the data were compared to control group data of similar gender and age groups. Results: Examining the demographic data, no statistically significant difference was found between the migraine patients and the healthy controls in terms of age, gender, migraine history, and migraine type. However, using Optical Coherence Tomography (OCT), it was determined that the mean vertical and horizontal cup-to-disk (c/d) ratios at the optic disc were significantly impaired in patients compared to the control group. Moreover, using Optical Coherence Tomography Angiography (OCTA), significant reductions in vessel density (VD) were detected in the foveal, parafoveal, perifoveal areas and in the superficial and deep capillary plexuses (SCP and DCP) of the patients. Conclusion: It is thought that these findings might be associated with a vasculopathy developing due to a pathology in the autonomic nervous system or impairments in the cerebral, ocular, or systemic circulation. The authors believe that the results achieved in the present study could be useful in the diagnosis, monitoring, and treatment of the disease.

A Fourier-based methodology without numerical diffusion for conducting dye simulations and particle residence time calculations

Dye experimentation is a widely used method in experimental fluid mechanics for flow analysis or for the study of the transport of particles within a fluid. This technique is particularly useful in biomedical diagnostic applications ranging from hemodynamic analysis of cardiovascular systems to ocular circulation. However, simulating dyes governed by convection-diffusion partial differential equations (PDEs) can also be a useful post-processing analysis approach for computational fluid dynamics (CFD) applications. Such simulations can be used to identify the relative significance of different spatial subregions in particular time intervals of interest in an unsteady flow field. Additionally, dye evolution is closely related to non-discrete particle residence time (PRT) calculations that are governed by similar PDEs. This contribution introduces a pseudo-spectral method based on Fourier continuation (FC) for conducting dye simulations and non-discrete particle residence time calculations without numerical diffusion errors. Convergence and error analyses are performed with both manufactured and analytical solutions. The methodology is applied to three distinct physical/physiological cases: 1) flow over a two-dimensional (2D) cavity; 2) pulsatile flow in a simplified partially-grafted aortic dissection model; and 3) non-Newtonian blood flow in a Fontan graft. Although velocity data is provided in this work by numerical simulation, the proposed approach can also be applied to velocity data collected through experimental techniques such as from particle image velocimetry.

Osteopathic manipulative treatment in improving symptoms and quality of life in patients with Graves’ ophthalmopathy: A case report

BackgroundGraves' Disease (GD) is an autoimmune disorder, with ∼50% of GD patients developing Graves’ Ophthalmopathy (GO). Common presentations include lid retraction, exophthalmos, disfigurement, ocular pain, and pressure. Treatment of GD depends on disease severity, ranging from artificial tears to ocular surgeries. Patients with GO symptoms experience a decreased quality of life (QoL) and could benefit from additional treatment options. ObjectiveThis case report describes the use of osteopathic manipulative treatment (OMT) as an adjunct to standard care for a patient with symptomatic GO, and measurement of treatment response with a standardized QoL assessment tool. Clinical featuresClinical evaluation of a patient with GO showed clinical activity score to be 4 with oppressive feeling behind globes, hyperemia, and eyelid edema. Corneal displacement measured by Hertel exophthalmometer indicated increased proptosis. CT scan showed enlarged extraocular muscles bilaterally, with signs of edema in retrobulbar fat. Visual acuity and optic nerves were within normal limits. Intervention and outcomesThis case report demonstrates the use of OMT in long-term reduction of ocular pain and pressure by relieving orbital myofascial tension along with improving ocular circulation, in a patient with GO. Using the European Group On Graves’ Orbitopathy QoL questionnaire, the patient noted better quality of life (93, 81.3 for pretreatment visual and appearance scores, respectively, and 100, 87.5 for post-treatment visual and appearance scores, respectively) and perceived reduced exophthalmos. ConclusionsProviding OMT as a cost effective, non-invasive treatment option for GO symptoms could meet a significant need for GO patients and warrants further study.

Ex vivo ocular perfusion model to study vascular physiology in the mouse eye

Several hypotheses have been tested to understand whole organ regulation in other organs such as the brain and kidney, but no such hypothesis has yet been proposed for ocular circulations. To some extent resolve this deficit our ex vivo mouse eye perfusion model takes the first step in elucidating the mechanisms controlling the individual components of the ocular circulation. Various isolated ocular vascular preparations have been utilized in studies of ocular vascular biology, physiology, and pharmacology, including studies on both normal and pathological conditions. However, there is still significant potential for further studies to improve our understanding of ocular circulation and its regulation. The choroid specifically is inaccessible to direct visualization due to the retina's high metabolic requirement with a transparency that cannot be compromised by an overly rich vascular network on the inner retinal side hindering the visualization of the choroid. In this technical paper, we provide a detailed description of all the steps to be followed from the enucleation of mouse eyes to cannulation of the ophthalmic artery and perfusion and ex vivo confocal microscopy imaging of the dynamic nature of the choroid circulation.

Evaluation of treatment response with color doppler ultrasonography in cases with primary open-angle glaucoma

Aims: Beta-blockers, the most frequently preferred drug group in glaucoma.Withcolor Doppler ultrasonography (CDU), the localization of retrobulbar vascular structures, their flow rates and directions, and the effects of the drugs used on the ocular circulation can be examined in a dynamic, reliable, and noninvasive way in less time than other techniques. The aim of our study was to compare the effects of beta-blockers, widely used in glaucoma treatment, and the additional neuroprotectant flunarizine on ocular hemodynamics using CDU. Methods: Between November 1998 and August 1999, 30 cases diagnosed with POAG in the GlaucomaUnit of the 1st EyeClinic of our center were included in the study. Patients were divided into 3 groups according to their beta-blocker treatment. Patients' CDU examinations were then examined by an experience dradiologist, and peaksys to lic flow velocity (PSFV) and end-diastolic flow velocity (EDFV) of the ophthalmicartery (OA), central retinal artery (CRA), and lateral (temporal) posterior ciliary arteries (LPCA) in the right or left eye were detected. Results: Of the 30 patients who participated in the study, 14 were male and 16 were female. Nine patients had hypertension (HT), 3 patients had diabetes (DM), and 6 patients had migraine. The mean age was similar in all three groups. There was a significant reduction in IOP in all three patient groups in whom IOP was measured after the use of topical beta-blockers (P&lt;0.01). The use of flunarizine had no effect on IOP in all three groups (P&gt;0.05). There was no statistically significant difference between groups in OA PSFVs and EDFVs at the first, second, and third measurements using the three beta-blockers (P&gt;0.05). No statistically significant difference existed between all three groups in the measurements of CRAPSFVs and EDFVs (P&gt;0.05). There were also no significant differences between groups in measurements of LPCA, PSFVs, and EDFVs at baseline and follow-up (P&gt;0.05). Conclusion: We found that the changes in hemodynamic parameters and reduction in IOP with all three beta-blockers were similar on color Doppler USG in patients using beta-blockers for the treatment of glaucoma. We observed that flunarizine had no effect on systemic hemodynamic parameters, did not affect IOP, and had no adverse effects on retrobulbar hemodynamic parameters when combined with beta-blockers. Local beta-blockers remain the mainstay of medical treatment for POAG because of their low systemic side effects and beneficial effects on the eye.

Effect of Nasal Septum Deviation on the Choroidal Thickness.

Nasal cavity blood circulation and ocular blood circulation have common pathways for both arterial blood supply and venous drainage. Therefore, nasal pathologies can affect ocular blood circulation. This study aimed to evaluate the relationship between nasal obstruction and choroidal thickness. A prospective study was planned by forming a group of 144 patients diagnosed with nasal septum deviation at the otorhinolaryngology clinic and 100 healthy voluntary individuals. Of the total, 69 patients with nasal right septum deviation were evaluated as Group 1, 75 patients with nasal left septum deviation as Group 2, and 100 healthy volunteers as the control group. Detailed ophthalmological examinations of all the participants were performed, and choroidal thickness was measured using spectral domain optical coherence tomography. The relationship between choroidal thickness and ocular parameters was evaluated and compared between the patient groups with nasal septum deviation and the control group. When the choroidal thickness measurements of the patients in Group 1 were examined, the choroidal thickness increased in all the regions in the eye contralateral to the deviation side (left), and intraocular pressure (IOP) was higher compared to the eye on the deviation side (right) and the control group at a statistically significant level. In Group 2, the choroidal thickness measurements increased in all the regions in the eye contralateral to the deviation side (right), and IOP was higher compared to the deviation side (left) and the control group. We found that the patients with nasal septum deviation hadhigher choroidal thickness and IOP values in the eye contralateral to deviation.

Disturbances of Ocular Circulation in Color Doppler Imaging, Retinal Changes and Electrophysiological Tests with Neuro-Ophthalmological Clinical Symptoms in the Course of CADASIL Syndrome—A Case Report

The authors present a new paper examining the disturbances in ocular circulation and electrophysiological changes in the presence of neuro-ophthalmic manifestations in a patient with cerebral autosomal dominant arteriopathy with subcortical infracts and leucoencephalopathy (CADASIL). Symptoms reported by the patient included: transient vision loss (TVL), migraines, diplopia, bilateral peripheral visual field loss and convergence insufficiency. CADASIL was confirmed by the presence of NOTCH3 gene mutation (p.Cys212Gly), the presence of granular osmiophilic material (GOM) in cutaneous vessels in an immunohistochemistry test (IHC) and bilateral focal vasogenic lesions in the white matter of the cerebral hemisphere, with micro-focal infarct in the left external capsule on a magnetic resonance imaging test (MRI). Color Doppler imaging (CDI) confirmed decreased blood flow and increased vascular resistance in the retinal and posterior ciliary arteries, with reduced P50 wave amplitude on a pattern electroretinogram (PERG). An eye fundus examination and fluorescein angiography (FA) revealed the constriction of retinal vessels and a peripheral retinal pigment epithelium (RPE) atrophy with focal drusen. The authors suggest that the cause of TVL may be changes in the hemodynamics of the retinochoroid vessels associated with the narrowing of small vessels and the presence of druses in the retina-which is supported by a decrease in the amplitude of the P50 wave in PERG, changes in OCT correlating simultaneously with changes in MRI imaging and other neurological symptoms.

Ocular circulation change in optic disc melanocytoma – a case report and a review of the literature

BackgroundOcular circulation in optic disc melanocytoma (ODM) has not yet been well evaluated. We quantitatively evaluated longitudinal changes in the morphology and circulation hemodynamics of the disc and macula using optical coherence tomography angiography (OCTA) and laser speckle flowgraphy (LSFG) in a patient with optic disc melanocytoma.Case presentationA 50-year-old woman was referred to our hospital due to a dark pigmented tumor over the superior optic disc area of the left eye noted on physical examination. At the first visit, the patient’s best-corrected visual acuity (BCVA) was 20/20 in both eyes, and the intraocular pressure (IOP) was 17 and 18 mmHg in the left and right eyes, respectively. Fluorescein angiography (FA) showed blockage of fluorescence in the topography of the lesion, and indocyanine green angiography (ICGA) showed hypofluorescence at all times. On LSFG, a low mean blur rate (MBR) was noted in the optic disc all area (MBRa) and tissue (MBRt) compared to the contralateral eye at the first visit and at the 3-month follow-up. A relatively low MBR was also detected in the macular area of the affected eye and the tumor itself. OCTA detected blood vessel networks in the deep retinal layer of the tumor. The visual field showed no specific defects. During follow-up, there was no tumor enlargement or vision decrease.ConclusionsWe found that a lower MBR of the disc and macula area was noted on LSFG in this patient with optic disc melanocytoma, and it was continually observed at the 3-month follow-up. Although blood vessel networks in the deep retinal layer of the tumor were detected by OCTA, vascular compromise in the surrounding disc area and macula was found. Therefore, these results further increase our knowledge about the role that circulation impairment plays in the pathogenesis of the disease while vision is unaffected.

The impact of obesity on ocular hemodynamics and choroidal thickness.

Obesity affects microvascular structures. The effect of obesity on the ocular vascular system can be evaluated by changes in the choroidal thickness (CT) and retrobulbar blood flow (RBF). To evaluate the CT and RBF parameters in obese patients with various body mass index (BMI) values and compare these parameters with normal weight, healthy subjects. A prospective study. The study included 102 eyes of 102 female patients. Patients were divided into three groups according to BMI as group 1 with a BMI of 18.5-24.99 (n = 32), normal weight group; group 2 with a BMI of 30-34.99 (n = 35), as obese class I; and group 3 with a BMI of 35-39.99 (n = 35), as obese class II. The peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index, and pulsatility index values of the central retinal artery (CRA) and ophthalmic artery (OA) were evaluated with color Doppler ultrasonography. CT was measured at the subfoveal area and at 500-µm intervals nasal and temporal to the fovea up to a distance of 1500 µm by using the enhanced depth imaging technique of optical coherence tomography. Intraocular pressure (IOP) was measured with a Goldmann applanation tonometry. There was a significant difference in IOP values within the groups with the highest values in group 3 (17.6 ± 2.1 mmHg) and the lowest in group 1 (12.4 ± 1.7 mmHg). The CT in groups 2 and 3 was found to be statistically significantly lower than that in group 1 at all measurement points (p < 0.001). There was a statistically significant negative correlation between CT at all measurement points and BMI (p < 0.001). The mean CRA PSV, EDV, and OA EDV values were statistically significantly lower in each obese group than those values in group 1 (p < 0.001). The OA PSV values were significantly lower in group 3 (36.5 ± 5.9 cm/s) than those in group 2 (43.8 ± 4 cm/s) and group 1 (44.6 ± 5.2 cm/s) (p < 0.001). Also, significant associations were found between BMI and CRA PSV, CRA EDV, and OA PSV values (p < 0.001). Obesity may predispose to eye pathologies by changing the ocular vascular circulation.

Dynamic Functional Test of Ocular Circulation

Dynamic Functional Test of Ocular Circulation

Effects of optic nerve head-related parameters on retinal vessel calibers measurement results on fundus photographs

BackgroundAlthough relationship between the retinal vessel caliber (RVC) and glaucoma is well known, there has been a paucity of information on the effects of glaucoma-related optic nerve head (ONH) structural factors on the RVC. Information on this relationship should be useful in studying possible roles of ocular circulation in the development and progression of glaucoma.MethodSubjects were from Kumejima Study participants aged 40 years and older in Kumejima, Japan. Normal subjects and eyes were defined according to standardized systemic and ocular examinations. The central retinal artery and vein equivalents (CRAE and CRVE) were determined on fundus photographs by correcting the magnification using the refractive error, corneal curvature, and axial length (AL) of an individual eye and paraxial ray tracing; the ONH structural parameters were determined by planimetry.ResultsIn a total of 558 right eyes (558 normal subjects), aged 49.0 ± 7.1 (standard deviation) years with gradable photographs and planimetric results, CRAE averaged 136.1 ± 12.3 μm and CRVE 216.9 ± 17.4 μm. After adjustment for the effects of confounding factors in multivariate analysis, the AL (P < 0.001), rim area (P = 0.019), disc area (P = 0.042), and smoking (P = 0.035–0.043) correlated positively, and the mean blood pressure (P < 0.001) negatively with CRAE; the AL (P < 0.001), rim area (P = 0.001), disc area (P = 0.005), smoking (P < 0.001), and male sex (P = 0.013) correlated positively, and the β-peripapillary atrophy (β-PPA) area (P = 0.044), vertical Cup/Disc ratio (v-C/D) (P = 0.035), and age (P < 0.001) negatively with CRVE.ConclusionThe current study showed significant effects of rim area, v-C/D or β-PPA area determined on the photographs on the RVC measurement results. Further, it showed a necessity to incorporate the glaucoma-related ONH structural parameters as co-variables to correctly estimate the effects of various factors on the RVC.

Effects of aging and exercise habits on blood flow profile of the ocular circulation.

We examined the effects of aging and exercise habits on the ocular blood flow (OBF) and its profiles throughout the optic nerve head region and choroidal area. We hypothesized that exercise habits reduce the stiffness of vessels in the ocular circulation, which generally increases with aging. Participants in a medical checkup program (698 males and 192 females aged 28 to 80 years) were categorized into 2 groups (with and without exercise habits) based on participant self-reporting and the definition of the Ministry of Health, Labor and Welfare of Japan (MHLW). OBF in the right eye was measured and analyzed using laser speckle flowgraphy. The blowout time (BOT), which is the time during which the blood flow is higher than half of the mean of the minimum and maximum signals during one heartbeat, was calculated as an index of the blood flow profile. BOT has been used as an indicator of the flexibility of blood vessels. BOT significantly decreased with aging. Neither the self-reported nor MHLW-based exercise habits significantly affected the ocular circulation. These results indicate that the stiffness of the ocular vessels increases with aging, and this cannot be prevented by exercise habits.

Оценка возрастных изменений параметров глазного кровотока диска зрительного нерва методом лазерной спекл-флоуграфии

The most common eye diseases, including glaucoma and diabetic retinopathy, are associated with impaired perfusion of the eye. To date, LSFG is a reliable method for quantifying ocular circulation. Purpose. To assess the ocular blood flow age- related changes using Laser Speckle Flowgraphy (LSFG). Material and methods. This cross-sectional study included 90 eyes of 45 healthy, non-smoking volunteers, between 20 to 75 years old. LSFG instrument was applied to measure ocular blood flow at the optic nerve head. The mean blur rate (MBR), a measure of relative blood flow velocity, was obtained for different regions of the ONH. Three parameters of ocular perfusion derived from the pulse-waveform analysis of MBR for big vessels (MV) and microcirculatory bad (MT) including blowout time (BOT), blowout score (BOS) and resistivity index (RI) were also recorded. Results. Artifact-free LSFG images meeting the quality criteria for automated image analysis were obtained. Measurements of MBR showed excellent repeatability. MBR-related blood flow indices exhibited significant age dependence (p&lt;0.05). BOT, BOS and RI changes also analysed. Conclusion. LSFG represents a reliable method for the quantitative assessment of ocular blood flow. Our data affirms that the LSFG-parameters may be useful biomarkers of ocular perfusion for age-related and patologic changes. Key words: ocular perfusion, microcirculation, optic nerve disc, laser speckle flowgraphy, LSFG, glaucoma, diabetic retinopathy

A study on effect of diabetes mellitus and hypertension on ocular blood flow by colour doppler ultrasonography

Background: Diabetes mellitus (DM) and hypertension (HT) have been the two major medical and public health issues for over 40 years worldwide. Colour doppler imaging (CDI) is widely used to evaluate ocular circulation. It is non-invasive, safe, and useful tool, most commonly used to investigate circulatory parameters in retrobulbar blood vessels. The aim was to study ocular blood flow (OBF) velocity in the ophthalmic artery (OA), central retinal artery (CRA) and central retinal vein (CRV) in patients with DM and HT by CDI. Materials and methods: A cross-sectional observational study was done for 6 months (June 2021–November 2021) on 40 patients of age 40 years and above with DM and/or HT of a minimum 6 months duration. Retrobulbar circulation was assessed in all subjects bilaterally. Subjects were further divided into groups with or without retinopathy. Results: Of the total number of 40 participants, 26 (65%) were male, and 14 (35%) were female. 16 (40%) participants were diabetics, 8 (20%) were hypertensive, and 16 (40%) had both DM and HT. 57.5% were diagnosed with retinopathy changes. The mean values of the pulsatile index (PI) were: 1.23 in patients with DM, 1.30 in patients with HTN, and 1.33 in patients with DM and HTN. Conclusion: Our study showed reduced blood flow velocity and increased resistivity index (RI) in patients with DM and/or HT. Significant changes were noted in retrobulbar blood flow in patients with retinopathy. These results can potentially provide prognostic values in times to come regarding altered OBF even before retinopathy develops.