Confocal Scanning Laser Doppler Research Articles

Factors associated with non-active retinal capillary density as measured with Confocal Scanning Laser Doppler Flowmetry in an elderly population: the Thessaloniki Eye Study (TES)

PurposeTo identify factors associated with retinal capillary density as measured with Confocal Scanning Laser Doppler Flowmetry (Heidelberg retina flowmeter (HRF)) in the Thessaloniki Eye Study (TES).MethodsParticipants of the TES (age...

Lutein Complex Supplementation Increases Ocular Blood Flow Biomarkers in Healthy Subjects.

Introduction: To investigate the effects of a lutein complex supplementation on ocular blood flow in healthy subjects. Materials and Methods: Sixteen healthy female patients (mean age 36.8±12.1years) were enrolled in this randomized, placebo-controlled, double-blinded, two-period crossover study. Subjects received daily an oral dose of the lutein with synergistic phytochemicals complex (lutein (10mg), ascorbic acid (500mg), tocopherols (364mg), carnosic acid (2.5mg), zeaxanthin (2mg), copper (2mg), with synergistic effects in reducing pro-inflammatory mediators and cytokines when administered together in combination) and placebo during administration periods. Measurements were taken before and after three-week supplementation periods, with crossover visits separated by a three-week washout period. Data analysis included blood pressure, heart rate, intraocular pressure, visual acuity, contrast sensitivity detection, ocular perfusion pressure, confocal scanning laser Doppler imaging of retinal capillary blood flow, and Doppler imaging of the retrobulbar blood vessels. Results: Lutein complex supplementation produced a statistically significant increase in mean superior retinal capillary blood flow, measured in arbitrary units (60, p=0.0466) and a decrease in the percentage of avascular area in the superior (-0.029, p=0.0491) and inferior (-0.023, p=0.0477) retina, as well as reduced systolic (-4.06, p=0.0295) and diastolic (-3.69, p=0.0441) blood pressure measured in mmHg from baseline. Data comparison between the two supplement groups revealed a significant decrease in systemic diastolic blood pressure (change from pre- to post-treatment with lutein supplement (mean (SE)): -3.69 (1.68); change from pre- to post-treatment with placebo: 0.31 (2.57); p=0.0357) and a significant increase in the peak systolic velocity (measured in cm/sec) in the central retinal artery (change from pre- to post-treatment with lutein supplement: 0.36 (0.19); change from pre- to post-treatment with placebo: -0.33 (0.21); p=0.0384) with lutein complex supplement; data analyses from the placebo group were all non-significant. Discussion: In healthy participants, oral administration of a lutein phytochemicals complex for three weeks produced increased ocular blood flow biomarkers within retinal vascular beds and reduced diastolic blood pressure compared to placebo.

MODERN APPROACH TO DIAGNOSTICS, PREVENTION AND CORRECTION OF ACNE SCARRING ON THE BASIS OF STUDY OF SKIN MORPHOLOGY BY NONINVASIVE METHODS

The efficacy of the long-acting drug of hyaluronidase (bovhyaluronidase azoximer, BHA) in acne and postacne patients has been studied. The main criteria for the efficacy of acne and post-acne therapy in the assessment by confocal laser scanning microscopy and laser Doppler flowmetry are proposed.Materials and methods. Randomized, double-blind, placebo-controlled study, comparative in parallel groups. 90 patients aged 18 to 35 years (23.76 ± 4.59 years) with medium and severe acne and postacne were divided into 2 groups of 45 each by randomization (the first group received BHA 3000ME, the second — a placebo). There were two methods of administration of drug or placebo: intramuscular injection or ultraphoonophoresis. Evaluation of the skin was performed by confocal laser scanning microscopy (CLSM) in vivo (VivaScope®, NY, USA), microcirculation — by the laser Doppler flowmetry (LDF) with the laser capillary blood flow analyzer (LAKK-01, Russia). The effectiveness was evaluated by the Qualitative scaring grading system and Goodman’s quantitative global acne scarring system.Results and conclusions: With the use of BHA 80 % of patients had an improvement, 8.89 % — a significant improvement, postoperative index was reduced from 14.27 ± 5.61 to 10.18 ± 4.63 points (p 0.05). In the placebo group the reduction of indices is insignificant. The effectiveness of the use of BHA by the ultraphonophoresis was lower than by intramuscular injection. A significant change in the microcirculation index (flux) was established from 20.09 ± 1.74 PU (Perfusion Units) up to 15.2 ± 2,1 PU (p = 0,01). The normalization of the microcirculation was noted. According to the results of CLSM, among BHA patients were observed a significant decrease of severe fibrosis and inflammatory infiltration, the number of dilated vessels. In the placebo group signs persisted. Clinical and morphological monitoring showed the expediency, high efficiency and safety of BHA in the therapy of patients with medium and severe acne vulgaris and postacne.

The role of retrobulbar and retinal circulation on optic nerve head and retinal nerve fibre layer structure in patients with open-angle glaucoma over an 18-month period

Background/aimsEvidence suggests that vascular abnormalities play a role in the pathogenesis of open-angle glaucoma (OAG) in some patients. This study aims to assess changes in retrobulbar and retinal blood flow...

Optic nerve head morphology in glaucoma patients of African descent is strongly correlated to retinal blood flow

Background/AimsTo examine the relationship between change in optic nerve head (ONH) morphology and retinal blood flow in patients with open-angle glaucoma (OAG) of African (AD) and European descent (ED) over...

The Influence of Retinal Blood Flow on Open-angle Glaucoma in Patients with and without Diabetes

To evaluate the impact of retinal blood flow on optic nerve head (ONH) morphology in patients with open-angle glaucoma (OAG) with and without diabetes mellitus (DM). A total of 66 patients with OAG (14 with DM, 52 without DM) were assessed at baseline and 3-year follow-up for retinal capillary blood flow using confocal scanning laser Doppler and ocular structure using Heidelberg retinal tomography and optical coherence tomography. Change in retinal tissue with zero blood flow in the superior and inferior retina was found to have a strong correlation with ONH changes in diabetic patients (r≥0.90, p≤0.03); however, no relation was found in the nondiabetic cohort. There were also significant changes in inferior mean flow that strongly correlated with changes in cup area (r = 0.97, p = 0.0029), cup/disc area ratio (r = 0.96, p = 0.0070), linear cup/disc ratio (r = 0.93, p = 0.0172), rim area (r = -0.97, p = 0.0036), and rim volume (r = -0.95, p = 0.0084) in diabetic patients only, while changes in the superior mean flow were only significantly associated with cup area (r = -0.30, p = 0.0498), cup volume (r = -0.36, p = 0.0178), and rim volume (r = 0.35, p = 0.0193) in nondiabetic patients. In this cohort of patients with OAG, changes in retinal capillary blood flow correlated more strongly with changes in ONH morphology in patients with DM than in those without DM. These data suggest that changes in retinal blood flow may play a larger role in glaucomatous ONH progression in patients with OAG with DM.

Should Men and Women be Managed Differently in Glaucoma?

IntroductionTo assess differences in associations of ocular perfusion pressure (OPP) as well as retinal and retrobulbar blood flow between men and women with primary open angle glaucoma (OAG).MethodsA total of 116 patients with OAG (age 66.9 ± 10.9 years, 70 females) participating in the Indianapolis Glaucoma Progression Study were assessed for OPP, retinal microcirculation, and retrobulbar blood flow. Confocal scanning laser Doppler flowmetry measured peripapillary retinal capillary blood flow. Color Doppler imaging measured peak systolic (PSV) and diastolic blood flow velocities and vascular resistance in the ophthalmic (OA), central retinal (CRA), and nasal and temporal short posterior ciliary arteries (N/T PCA). Bivariate Spearman correlation and multivariate linear regression analyses were performed.ResultsIn female patients with OAG, inferior retinal capillary flow was associated with OPP (r = 0.246, P = 0.044). In men, superior and inferior sector retinal blood flow was associated with OPP (r = −0.402, P = 0.006 and r = −0.357, P = 0.016, respectively). There was no statistically significant association between OPP and retrobulbar blood vessel flow velocities in male patients with OAG but there was an association between OA and TPCA PSV and OPP in female patients with OAG (r = 0.290, P = 0.015 and r = 0.357, P = 0.002, respectively). In female patients with OAG, multivariate regression showed no statistically significant effect of any variable on the superior retinal capillary blood flow, with CRA PSV as a sole predictor to the inferior retinal sector (partial rho = 0.302, P = 0.015) and in male patients with OAG, superior sector retinal capillary blood flow was independently associated with intraocular pressure (partial rho = −0.371, P = 0.016) and OPP (partial rho = −0.456, P = 0.002) with a trend of association with OPP in the inferior retina (partial rho = −0.301, P = 0.053).ConclusionsThere was a positive linear association between retinal microcirculation and OPP in females and a negative association in males. Male and female patients with OAG may differ in their vascular autoregulation in response to changes in OPP.

Basic technique and anatomically imposed limitations of confocal scanning laser Doppler flowmetry at the optic nerve head level

Many studies have suggested an association between blood flow dysregulation and glaucomatous damage to the optic nerve. Confocal scanning laser Doppler flowmetry (CSLDF) is a technique that measures the capillary blood flow of the retina and optic nerve head and provides a two-dimensional map of ocular perfusion in these areas. This review discusses the anatomy of the anterior optic nerve vasculature and the capabilities and limitations of the CSLDF. Methods to minimize error and to acquire more reliable measurements of capillary blood flow are also outlined.

Macular blood flow measured by blue‐field entoptoscopy and Heidelberg retinal flowmetry: comparison of two techniques in type 1 diabetes women during pregnancy

This study compared macular capillary leucocyte velocity values measured with a psychophysical blue-field entoptic simulation (BFS) technique and confocal scanning laser Doppler flowmetry. A cross-sectional study was performed where macular capillary leucocyte velocity was measured by BFS using an Oculix BFS-2000 V2.1 psychophysical system and by confocal scanning laser Doppler flowmetry using Heidelberg retinal flowmetry (HRF) in 35 type 1 diabetes women during the second trimester. The macular leucocyte velocities measured with BFS correlated significantly with the 50th percentile (r = 0.345, p = 0.042, n = 35, Spearman's non-parametric correlation), the 75th percentile (r = 0.432, p = 0.009) and the 90th percentile (r = 0.373, p = 0.027) of HRF flow values during the second trimester. However, there was no correlation between BFS velocity and the 25th percentile of HRF measurements. Blue-field simulation is known to be an experimental technique that provides a quantitative measure of flow in the perifoveal capillary network. By contrast, HRF imaging reflects quantitative, multispectral, objective and non-invasive measurements in a two-dimensional projection of a three-dimensional retinal capillary bed. Our study showed that BFS velocity was correlated with HRF values in a group of women with diabetes during pregnancy. The positive correlation between BFS and HRF values suggests that the psychophysical BFS and scanning laser-based HRF measure similar functions in the retina.

Inability of a Confocal Scanning Laser Doppler Flowmeter to Measure Choroidal Blood Flow in the Pig Eye

The aim of the study was to determine whether the Heidelberg Retinal Flowmeter (HRF), a confocal scanning laser Doppler flowmeter, can measure choroidal blood flow in pig eyes.An HRF was used to obtain flow maps from in vitro pig eyes under a range of perfusion flow rates (0 – 500 µL/min) under conditions in which only the choroid was perfused. In some cases choroidal blood flow was also measured simultaneously using a conventional fiberoptic based Laser Doppler Perfusion Monitor (LDPM) which used the same laser wavelength (780 nm). The relationship between perfusion flow, HRF measured flow and LDPM measured flow was determined. HRF flow maps were also obtained in vivo as a function of focal plane setting through the retina and choroid.Across the range of perfusion flow rates through the isolated eyes there was a poor correlation with HRF measured choroidal flow and perfusion flow. In contrast, there was a strong linear relationship between perfusion flow and LDPM measured blood flow. Both in vitro and in vivo, no choroidal vessels could be visualised in the HRF flow maps, even when the focal plane was in the choroid.The HRF is unable to measure choroidal blood flow in pig eyes. This is not due to an inability of the 780 nm laser to penetrate into the choroid or due to red blood cell velocities in the choroid being higher than the measurement range of the instrument.

The effects of raloxifene hydrochloride on ocular hemodynamics and visual function

To assess the comprehensive effects of raloxifene hydrochloride on retinal, choroidal and retrobulbar hemodynamics and on visual function in post-menopausal women. Twenty-four post-menopausal women (age 55 +/- 3.8 years) were recruited for this cross-sectional study: 12 received placebo and 12 received raloxifene hydrochloride 60 mg once a day for 3 months. Baseline measurements of both groups included heart rate (HR), blood pressure (BP), visual acuity, contrast sensitivity and intraocular pressure (IOP) for both eyes. A comprehensive ocular blood flow (OBF) assessment was obtained for each patient in a randomly chosen study eye. Retinal blood flow data was obtained using confocal scanning laser Doppler flowmetry [Heidelberg Retinal Flowmeter (HRF)]. Color Doppler imaging (CDI) was used to assess retrobulbar hemodynamics in the ophthalmic, central retinal, short nasal and temporal posterior ciliary arteries. Baseline vision and hemodynamics in post-menopausal subjects were compared using paired Student's t tests, and the percentage change in baseline versus 3-month parameters was analyzed. There were no statistically significant differences between 3 months of raloxifene therapy and placebo in terms of age, HR, arterial or mean BP, visual acuity, contrast sensitivity, IOP or retinal or retrobulbar blood flow. Raloxifene therapy at 60 mg/day had no clinically significant impact on BP, IOP or OBF in post-menopausal women.

A comparative study of the effects of brinzolamide and dorzolamide on retinal oxygen saturation and ocular microcirculation in patients with primary open-angle glaucoma

Aims:To assess the effects of brinzolamide and dorzolamide on ocular haemodynamics and retinal oxygen saturation in patients with primary open-angle glaucoma (OAG).Methods:Fifteen patients with OAG were evaluated in a randomised,...

A Comparative Analysis of the Effects of the Fixed Combination of Timolol and Dorzolamide Versus Latanoprost Plus Timolol on Ocular Hemodynamics and Visual Function in Patients with Primary Open-Angle Glaucoma

The aim of this study was to assess the effects of fixed combination of timolol and dorzolamide and latanoprost plus timolol on retinal, choroidal, and retrobulbar hemodynamics and visual function in primary open-angle glaucoma (OAG) subjects. Sixteen (16) OAG patients (age, 63.5 +/- 10.8 years; 9 male) were evaluated in a randomized, crossover, double-blind study design after 4 weeks of treatment of latanoprost with timolol and fixed combination of timolol and dorzolamide. After randomization, 9 right eyes and 7 left eyes were included in the hemodynamic portion of the study. Measurements included: adverse events check, visual acuity, contrast sensitivity, blood pressure, heart rate, intraocular pressure (IOP), and fundus examination. Ocular blood flow was assessed using confocal scanning laser Doppler flowmetry, color Doppler imaging, and scanning laser ophthalmoscopy. Both therapies were effective at lowering IOP, whereas there was no statistically significant difference between latanoprost plus timolol and the fixed combination of timolol and dorzolamide (13.9% and 12.2% reduction, respectively; P = 0.5533). Fixed combination of timolol and dorzolamide significantly increased central retinal artery end diastolic blood flow velocity (P = 0.0168) and lowered resistance to flow (P = 0.0279). Temporal posterior ciliary artery peak systolic and end diastolic velocities were significantly increased with the fixed combination of timolol and dorzolamide (P = 0.0125 and 0.0238, respectively). Latanoprost plus timolol had no significant effects on ocular blood flow during 4 weeks of treatment. There were no statistically significant differences in adverse events, blood pressure, heart rate, visual acuity, contrast sensitivity scanning laser ophthalmoscopy, or Heidelberg Retinal Flowmeter for any treatment period. Fixed combination of timolol and dorzolamide therapy might increase blood flow in OAG patients while attaining a similar IOP reduction compared to latanoprost plus timolol. Visual function, however, was not different in this short-term comparison between the two treatments.

Retinal Peripapillary Blood Flow before and after Topical Brinzolamide

Purpose: To study the effect of topical brinzolamide on retinal capillary blood flow by the Heidelberg Retina Flowmeter (HRF) in patients with glaucoma. Methods: Twenty patients with glaucoma were consecutively recruited. One eye for each patient was randomly selected. Patients were classified as glaucomatous if they had an abnormal visual field and/or an abnormal optic nerve head with an intraocular pressure (IOP) greater than 21 mm Hg without any treatment. After an eye examination, baseline retinal blood flow measurements were made with confocal scanning laser Doppler flowmetry. Blood flow and IOP measurements were then repeated after 1 month of treatment. Blood flow measurements were analyzed by using an automatic full-field perfusion image analysis (AFFPIA) program. The blood flow was calculated in the superior and inferior part of the optic disk. In each area, the blood flow was calculated as temporal area, the nasal area and the rim area as for software AFFPIA. Results: The mean age of the patients was 56 ± 7 (mean ± standard deviation) years. The mean IOP before treatment was 23.7 ± 1.5 mm Hg while the mean IOP after 4 weeks of treatment was 19.1 ± 2.2 mm Hg. This difference was statistically significant (p < 0.01). Significant (p < 0.05) increases in retinal blood flow were found for the temporal and nasal areas between baseline and 1 month after the treatment. No difference was found between superior and inferior sectors. Conclusion: Topical brinzolamide reduced the IOP significantly and apparently improved retinal blood flow as measured by the HRF.

Stellate ganglion block increases blood flow into the optic nerve head and the peripapillary retina in human

The effects of stellate ganglion block (SGB) on the blood flow of the optic nerve head (ONH) and the peripapillary retina, which plays an important role in the pathogenesis of a major blinding disease, e.g. glaucoma, are unclear. The aim of this study was to evaluate the effects of a sympathetic block on the blood flow of the ONH and the peripapillary retina. Heidelberg Retinal Flowmetry, which is a system incorporating a noninvasive confocal scanning laser Doppler flow meter, was used to measure the retinal blood flow. A unilateral stellate ganglion block was performed in 11 healthy subjects. The retinal blood flows were measured before, 30 and 120 min after SGB. On each occasion, three scans were obtained and the blood flow was analyzed. The systemic blood pressure (BP) and the intraocular pressure (IOP) were also measured at the set time points. The blood flow of the ONH and the peripapillary retina of the ipsilateral retina was significantly increased ( P=0.001) by 106.8% and 98.7%, respectively, 30 min after SGB without accompanying significant changes in BP and IOP when compared to their baseline values; while those of the contralateral eyes did not change. The effect of SGB on blood flow in these areas disappeared 120 min after SGB. In conclusion, SGB may have a beneficial effect on ocular diseases associated with ischemia of the ONH and the peripapillary retina, e.g. glaucoma.

Optic nerve head behavior in Posner-Schlossman syndrome.

To analyze the effect of glaucomatocyclitic crisis on the optic nerve head, as well as its consequent structural and hemodynamic changes. To evaluate the surgical indication for Posner-Schlossman syndrome. Four Posner-Schlossman syndrome cases were evaluated for an analysis of the phenomena occurring in the optic disc by means of retinal confocal tomography and Scanning Laser Doppler Flowmetry, and their correlation with visual function as measured with automated computerized perimetry. In all cases the images were obtained in the mediate period after the attack, while in case 1, measurements were performed in the immediate and mediate periods before, during and after the attack. Significant differences were found between optic nerve head parameters and retinal flow measurements in the different phases evaluated. No permanent optic nerve head damage was demonstrated in any of the cases studied, except for case 4 (Posner-Schlossman syndrome associated with traumatic glaucoma). All the variables analyzed returned to normal values after remission of the acute rise in intraocular pressure. During the attacks of ocular hypertension the optic nerve head experiences significant morphologic changes and hemodynamic variations; nevertheless since they are transient, they fail to cause permanent damage. There was only one case, in which there was optic disc damage and visual field loss. It can be concluded that surgery should be restricted to those cases with severe and disabling symptoms (relative surgical indication) or to cases with progressive optic neuropathy with visual field loss, when the syndrome is associated with glaucoma (absolute surgical indication).

The effect of brimonidine tartrate on retinal blood flow in patients with ocular hypertension

PURPOSE: To study the effects of topical brimonidine tartrate 0.2%, an α 2-agonist ocular hypotensive drug, on retinal capillary blood flow in patients with ocular hypertension. METHODS: The study was a double-masked, randomized, placebo-controlled trial set in a tertiary eye center. Ocular hypertensive patients with repeatable intraocular pressures greater than 21 mm Hg and normal visual fields and optic disks were consecutively recruited. After an eye examination, baseline retinal blood flow measurements were made with confocal scanning laser Doppler flowmetry in one study eye. Patients were then randomly assigned to receive either brimonidine or placebo (saline) twice daily for 8 weeks. Blood flow and intraocular pressure measurements were then repeated after 4 and 8 weeks. RESULTS: Seventeen patients were randomly assigned to receive brimonidine, and 14 received placebo. One patient in each group failed to complete the study. The mean group differences in baseline age and intraocular pressure were not statistically significant (59.23 [±10.24] and 52.23 [±16.46] years, respectively, and 24.84 [±2.08] and 24.56 [±2.85] mm Hg, respectively). Brimonidine reduced intraocular pressure by 17.90% and 16.17% at 4 and 8 weeks, respectively, with a significant difference in treatment effect compared with the placebo group ( P < .007). The group difference in treatment effect in any of the three hemodynamic parameters velocity, volume, and flow was within 8% and not significantly different at 4 or 8 weeks ( P > .360). Based on a type I error of 0.05, our study had a power greater than or equal to 75% to detect group differences in treatment effect of greater than or equal to 15% to 20%. CONCLUSIONS: Brimonidine reduces intraocular pressure without altering retinal capillary blood flow in patients with ocular hypertension.

A review of ocular blood flow measurement techniques

Several major eye diseases may be characterized by deficits in ocular blood flow. Maintaining adequate nutrient delivery to the choroid, retina, and optic nerve head may prevent cellular damage and loss, complementing efforts to provide neuroprotection. The ability to quantify deficits in ocular blood flow has increased in recent years with the introduction of several new techniques. 1) Scanning laser ophthalmoscopic fluorescein angiography allows the measurement of bulk retinal flow and macular capillary transit rates. 2) Scanning laser ophthalmoscopic indocyanine green angiography measures choroidal perfusion in selected areas near the optic nerve head and macula. 3) Confocal scanning laser Doppler flowmetry permits quantitation of retinal capillary perfusion. 4)Color Doppler ultrasound imaging measures flow velocities in the ophthalmic, central retinal, and short posterior ciliary arteries. While these techniques represent a major advance, significant issues regarding blood flow and ocular disease remain. First, the hemodynamic characteristics of the disease state need further definition. Second, the blood flow effects of current and future treatments must be established. Third, improvements in ocular blood flow techniques are required, both to increase anatomic precision and to allow non-invasive measurements during times of potential ischemic risk such as sleep. These developments could enhance prevention, diagnosis, and treatment of several major eye diseases.

Intraocular pressure and progression of glaucomatous visual field loss

PURPOSE: To study the effects of topical brimonidine tartrate 0.2%, an α 2-agonist ocular hypotensive drug, on retinal capillary blood flow in patients with ocular hypertension. METHODS: The study was a double-masked, randomized, placebo-controlled trial set in a tertiary eye center. Ocular hypertensive patients with repeatable intraocular pressures greater than 21 mm Hg and normal visual fields and optic disks were consecutively recruited. After an eye examination, baseline retinal blood flow measurements were made with confocal scanning laser Doppler flowmetry in one study eye. Patients were then randomly assigned to receive either brimonidine or placebo (saline) twice daily for 8 weeks. Blood flow and intraocular pressure measurements were then repeated after 4 and 8 weeks. RESULTS: Seventeen patients were randomly assigned to receive brimonidine, and 14 received placebo. One patient in each group failed to complete the study. The mean group differences in baseline age and intraocular pressure were not statistically significant (59.23 [±10.24] and 52.23 [±16.46] years, respectively, and 24.84 [±2.08] and 24.56 [±2.85] mm Hg, respectively). Brimonidine reduced intraocular pressure by 17.90% and 16.17% at 4 and 8 weeks, respectively, with a significant difference in treatment effect compared with the placebo group ( P < .007). The group difference in treatment effect in any of the three hemodynamic parameters velocity, volume, and flow was within 8% and not significantly different at 4 or 8 weeks ( P > .360). Based on a type I error of 0.05, our study had a power greater than or equal to 75% to detect group differences in treatment effect of greater than or equal to 15% to 20%. CONCLUSIONS: Brimonidine reduces intraocular pressure without altering retinal capillary blood flow in patients with ocular hypertension.

Peripapillary retinal blood flow in normal tension glaucoma

AIMSTo determine if normal tension glaucoma (NTG) patients differ from age matched controls in blood flow to the peripapillary retina, as measured with confocal scanning laser Doppler flowmetry (cSLDF; “Heidelberg...