Heidelberg Retina Flowmeter Research Articles

Impact of type 1 diabetes and its duration on wall-to-lumen ratio and blood flow in retinal arterioles.

Subclinical damage to both the small and large vessels may contribute to the development and progression of cardiovascular disease. Scanning laser Doppler flowmetry (SLDF), an established method used to measure retinal microcirculation, has been successfully applied in hypertensive and post-stroke patients. Retinal microcirculation was assessed in 158 patients with type 1 diabetes and 38 age-matched healthy controls. The diabetics were divided into 3 groups: group A with diabetes duration <12months, group B with diabetes with 1-10years, and group C >10years of diabetes. Retinal capillary structure and perfusion were evaluated using a Heidelberg retina flowmeter and automatically analyzed with full-field perfusion imaging. Age and BMI were comparable in all the diabetic patients and the controls (mean age 24.8±4.7years, mean BMI 22.9±4.1). In the univariate analyses, RCF (retinal capillary flow) was significantly higher in group A (297±121 arbitrary units [AU]) vs group B (236±52AU; p=0.007) and group C (236±70AU; p=0.008) and comparable to that of the controls (p=0.46). Additionally, the WLR (Wall-to-Lumen Ratio) was highest in group C compared to the other diabetic subgroups and controls (p=0.001). Multivariate regression analyses including age, BMI, sex, HbA1c, smoking, systolic blood pressure, and diabetes duration as covariates, showed, that only diabetes duration was significantly associated with WLR variations, whereas HbA1c was significantly linked to retinal capillary flow levels. New-onset diabetes is associated with an increase in RCF, which then gradually decreased with the duration of the disease. Structural changes of the retinal arterioles estimated via WLR are evident later in the course of diabetes, especially when the disease duration exceeded 10years.

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...

The short-term effect of acupuncture on different ocular blood flow parameters in patients with primary open-angle glaucoma: a randomized, clinical study.

IntroductionTo investigate the effect of acupuncture on different ocular blood flow (OBF) parameters in patients with primary open-angle glaucoma (POAG).Patients and methodsIn a prospective, randomized study, 56 POAG patients were randomly assigned either to an eye-specific acupuncture (group I, n=28) or to an eye-unspecific acupuncture treatment (group II, n=28). Blood flow parameters were measured before and 10 minutes after treatment. Parapapillary retinal blood flow was determined by the Heidelberg retina flowmeter. Retinal vessel diameters were measured by the dynamic vessel analyzer. Pulsatile ocular blood flow, ocular pulse amplitude, and IOP were investigated by the Langham OBF system. Systemic blood pressure was obtained additionally.ResultsPulsatile ocular blood flow increased significantly after the eye-specific acupuncture treatment from 5.6±4.3 to 6.7±4.9 µL/min (P=0.014). There was no significant change in parapapillary retinal blood flow, retinal vessel diameter, systemic blood pressure, or IOP after treatment in neither of the two groups.ConclusionAn eye-specific acupuncture treatment may affect OBF in POAG patients.

PP.41.12

Objective: Vascular remodeling in the retinal circulation represents an easily accessible, non-invasive, in-vivo possibility to assess early microvascular changes, especially as a model of brain microperfusion. In addition to the assessment of functional (e.g. retinal capillary flow, RCF) and retinal arterial structural parameters (e.g. wall-to-lumen-ratio, WLR) we now introduce a new parameter reflecting the resistance in small retinal arterioles. Design and method: In 66 normotensive (NT) and 107 hypertensive (HT) patients we assessed RCF, WLR, arteriolar diameter, lumen diameter and cross section area in the retinal circulation by using scanning laser doppler flowmetry SLDF at 670 nm (Heidelberg Retina Flowmeter, Heidelberg Engineering, Germany). Patients have been included in various randomized controlled trials, but with all the same study protocol at baseline. Mean arterial pressure was measured immediately before the SLDF measurement. We calculated the vascular resistance of the retinal arterioles (VRRA = MAP/RCF). In a separate study the test-retest reliability was determined in 6 volunteers from our clinical staff by assessing VRRA three times within six weeks. Results: The analysis of the volunteers revealed a coefficient of variation for VRRA of 7.75 ± 2.11% and Cronbach[Combining Acute Accent]s alpha was 0.90. The HT group did not show a more pronounced vascular remodeling of retinal arterioles (WLR, CSA, see table 1) compared to the NT group. In contrast RCF was greater in the HT group than in the NT group (p = 0.023). Our new suggested parameter VRRA was significantly greater in the HT group than in the NT group (p < 0.001). In both groups there is a significant correlation of VRRA with WLR (NT: r = 0.34, p = 0.006; HT: r = 0.25, p = 0.01), indicating that the VRRA reflects vascular remodeling in the retinal circulation.Conclusions: The analysis of the study data showed an increased vascular resistance in retinal arterioles in hypertensive patients compared to non-hypertensive patients before the occurrence of a change in structural retinal vascular remodeling parameters. The appearance of a significant correlation between VRRA and WLR indicates VRRA to be a new, reliable, non-invasive and early-sensitive marker of hypertensive disease.

Provocative intraocular pressure challenge preferentially decreases venous oxygen saturation despite no reduction in blood flow.

Ocular disease can both alter the retina's oxygen requirements, and decrease its ability to cope with changes in metabolic demand. We examined the influence of a moderate intraocular pressure (IOP) elevation on three outcome measures: arterial and venous oxygen saturation, blood flow, and the pattern electroretinogram (PERG). We increased IOP to ˜30mmHg in 23 healthy participants (22-39years) using a mechanical probe applied to the eyelid, thereby lowering ocular perfusion pressure (OPP) by ~30%. The Oxymap retinal oximeter was used to measure oxygen saturation for arteries and veins. Blood flow, volume and velocity were measured using the Heidelberg retinal flowmeter and steady-state PERG waveforms (8.34Hz) were recorded bilaterally (200 sweeps). For each outcome measure, data was obtained three times: at baseline, 1min into sustained IOP elevation, and 1min after the probe was removed. During IOP elevation, changes in oxygen saturation of retinal arteries failed to reach statistical significance [F(1,30)=3.69, p=0.05], whereas venous oxygen saturation was significantly reduced [F(1,21)=27.43, p<0.01]. Blood flow increased slightly [F(2,40)=6.28, p<0.0001], PERG amplitude significantly reduced [F(2,44)=24.24, p<0.0001] and PERG phase was significantly delayed [F(2,44)=17.00, p<0.0001]. Contralateral eyes were unchanged. OPP reduction correlated little with PERG amplitude, PERG phase or venous oxygen saturation. Mild, acute IOP elevation increases arterio-venous oxygen saturation differences primarily through lowering venous oxygen saturation, suggesting increased oxygen consumption by healthy neurons when physiologically stressed.

Effect of antihypertensive treatment on microvascular structure, central blood pressure and oxidative stress in patients with mild essential hypertension

It has been previously demonstrated that dihydropyridine calcium channel blockers may possess antioxidant properties and might improve vascular structure. Combination treatment with an angiotensin-converting enzyme inhibitor may have additional advantages, compared with a thiazide diuretic, in this regard. The aim of the present study was, therefore, to investigate the effects of a short-term treatment with lercanidipine, and to compare two combination treatments: lercanidipine + enalapril vs. lercanidipine + hydrochlorothiazide on structural alterations in retinal arterioles, on skin capillary density and on large artery distensibility. Twenty essential hypertensive patients were included in the study and treated for 4 weeks with lercanidipine 20 mg per day orally. Then they were treated for 6 months with lercanidipine + enalapril (n=10) or lercanidipine + hydrochlorothiazide (n=10) combinations. Investigations were performed in basal condition, after appropriate washout of previous treatments, after 4 weeks of lercanidipine monotherapy treatment, and at the end of the combination treatment. Non-invasive measurements of wall-to-lumen ratio (W/L) and other morphological parameters of retinal arterioles using scanning laser Doppler flowmetry were performed (Heidelberg Retina Flowmeter, Heidelberg Engineering). Capillary density was evaluated by capillaroscopy, whereas pulse wave velocity and central blood pressure were assessed by the Sphygmo-Cor device (AtCor Medical West Ryde, Australia). A significant improvement of W/L and of other indices of retinal artery structure was observed after treatment with lercanidipine alone, with a further improvement after treatment with lercanidipine + enalapril, whereas after treatment with lercanidipine + hydrochlorothiazide the improvement was no longer observed. A similar behaviour was observed for central SBP and DBP. Capillary density was increased only after treatment with lercanidipine + enalapril. Lercanidipine both in monotherapy and in combination with enalapril, was able to improve microvascular structure and to decrease central blood pressure, being thus a useful approach for both reducing blood pressure and improving vascular alterations in hypertension.

Retinal Microcirculation in Type 1 Diabetic Patients With and Without Peripheral Sensory Neuropathy.

In patients with diabetes mellitus (DM), early retinal microvascular alterations can be observed even before the clinical diagnosis of diabetic retinopathy. This study aimed to investigate morphological and functional changes in retinal microvascular blood flow in type 1 diabetic patients with and without peripheral neuropathy (PNP) as compared to nondiabetic controls. Retinal microvascular blood flow (RBF) was assessed using scanning laser Doppler flowmetry (Heidelberg Retina Flowmeter, Heidelberg Engineering, Germany) before and after stimulation with flicker light. PNP was assessed using the neuropathy disability score (NDS) and by the evaluation of the vibration perception threshold (VPT). A total of 41 subjects were recruited for study participation and were stratified to 3 different groups according to their metabolic and neurological status: 14 nondiabetic subjects without PNP, 14 diabetic patients without PNP, and 13 diabetic patients with PNP. All subjects were free from diabetic retinopathy as assessed by fundoscopy. In diabetic patients with PNP, baseline and stimulated RBF was higher compared with diabetic patients without PNP and the nondiabetic control group. No difference with regard to RBF could be observed between the nondiabetic control subjects and patients with type 1 DM without PNP. No difference in the arterial WLR could be observed between the 3 groups. A linear correlation was found for VPT and RBF (r = .38, P < .001) and for NDS and RBF (r = .44, P < .0001). In our study population of patients with type 1 diabetes, PNP was associated with functional but not morphological changes in RBF.

Change in retinal blood flow and retinal arterial diameter after intraocular pressure reduction in glaucomatous eyes

To study retinal blood flow and vessel diameter after intra-ocular pressure (IOP) reduction in high- and low-pressure glaucomas, that is, exfoliation glaucoma (ExG) and normal-tension glaucoma (NTG). The study included 17 eyes with ExG and 20 with NTG. A minimum of 25% IOP reduction was achieved by deep sclerectomy. Blood flow in the temporal peripapillary retina was measured with scanning laser Doppler flowmetry (Heidelberg Retina Flowmeter, HRF), and retinal vessel diameters were evaluated with the retinal vessel analyser (RVA). Examinations were carried out before and 3months after the operation. Pre-operative IOP was significantly higher in ExG than in NTG (median 26mmHg, range 20-33mmHg versus 15mmHg, 12-20; p<0.001). Surgery reduced IOP significantly both in ExG eyes (postoperative IOP 13mmHg, 5-17; p<0.001) and NTG eyes (9mmHg, 3-13; p<0.001). After the operation, systolic retinal flow was significantly reduced in ExG eyes, whereas in NTG, HRF parameters remained unchanged. Pre-operatively, the central retinal artery equivalent (CRAE) and arteriovenous ratio (AVR) were higher in ExG than in NTG eyes. After IOP reduction, both CRAE and AVR were reduced in ExG eyes, but remained unchanged in NTG. The study showed that before IOP reduction, arterial diameter was larger in ExG eyes than in NTG eyes. IOP reduction resulted in vasoconstriction and reduction of flow in ExG, whereas in NTG, both vessel diameter and retinal flow remained unchanged.

Relationship between wall-to-lumen ratio of retimal arterioles and clinic and 24 hours blood pressure

Objective: Wall-to-lumen ratio of retinal arterioles might serve as an in-vivo parameter of vascular damage. Previuos studies have shown a correlation between retinal arteriolar structure and blood pressure values, measured both in the clinic and during 24 hours ambulatory monitoring. We analyzed the impact of brachial clinic blood pressure (BP), of central BP and of 24 hours BP values on wall-to-lumen ratio of retinal arterioles. Methods: In 267 subjetcts (129 males, age range 20-72 years; mean 54±7 years) wall-to-lumen ratio of retinal arterioles was assessed in vivo using scanning laser doppler flowmetry (Heidelberg retina flowmeter, Heidelberg Engeneering). In addition clinic and 24 hours BP values were measured. Central hemodynamics and augmentation index (Ai) were assessed by pulse wave analysis. Results: In never treated patients with essential hypertension (n = 56) a higher wall-to-lumen ratio (0.37±0.19 vs. 0.30±0.13, P=0.05) was observed in comparison with normotensive individuals (n = 115); no significant differences were observed between treated (n=96) and untreated hypertensive patients. Wall to lumen ratio and wall cross sectional area of retinal arterioles were significantly related to clinic systolic BP (r=0.23, P=0.005) and PP (r=0.18, P=0.005), to 24 hours systolic BP (r=0.28, P=0.0001)and PP (r=0.19, P=0.003) and to central systolic BP (r=0.20, P=0.01) and central PP (r=0.21, P=0.001). Multiple regression analysis including all BP indices revealed that only mean systolic 24 hours BP is independently associated with an increased wall-to-lumen ratio of retinal arterioles. Conclusion: In this quite large group of hypertensive patients and normotensive individuals 24 hours systolic BP seems to be the strongest determinant of increased WLR of retinal arterioles.

Relationship between media-to-lumen ratio of subcutaneous small arteries and wall-to-lumen ratio of retinal arterioles evaluated noninvasively by scanning laser Doppler flowmetry

Structural alterations of subcutaneous small resistance arteries, as indicated by an increased media-to-lumen ratio, are frequently present in hypertensive and/or diabetic patients, and may represent the earliest alteration observed. Furthermore, media-to-lumen ratio of small arteries evaluated by micromyography has a strong prognostic significance; however, its extensive evaluation is limited by the invasivity of the assessment, since a biopsy of subcutaneous fat is needed. Noninvasive measurement of wall-to-lumen of retinal arterioles using scanning laser Doppler flowmetry (SLDF) has recently been introduced. However, this new technique has not yet been compared to micromyographic measurement, generally considered the gold standard approach. We investigated 40 individuals and patients, 24 of them were hypertensive patients and 16 normotensive individuals. All patients underwent a biopsy of subcutaneous fat during an elective surgical intervention. Subcutaneous small resistance arteries were dissected and mounted on a wire myograph, and media-to-lumen ratio was measured. In addition, an evaluation of wall-to-lumen ratio of retinal arterioles by SLDF was performed (Heidelberg Retina Flowmeter, Heidelberg Engineering). A close correlation was observed between media-to-lumen ratio of subcutaneous small arteries and wall-to-lumen ratio of retinal arterioles (r = 0.76, P < 0.001; P < 0.001, r(2) = 0.57). A noninvasive and easily repeatable procedure (intraobserver and interobserver variation coefficient <13%) such as an evaluation of the arterioles in the fundus oculi by SLDF may provide similar information regarding microvascular morphology compared with an invasive, accurate and prognostically relevant micromyographic measurement of media-to-lumen ratio of subcutaneous small arteries.

Pilot Study for the Evaluation of Morphological and Functional Changes in Retinal Blood Flow in Patients with Insulin Resistance and/or Type 2 Diabetes Mellitus

The aim of this study was to investigate early morphological and functional pathology in the retinal micro-circulation in patients with insulin resistance and/or type 2 diabetes mellitus (T2DM). Fifty-four subjects, without features of retinopathy under ophthalmological investigation, were recruited for study participation and were classified into three study groups according to their metabolic staging: (1) Group C comprised nondiabetic, insulin-sensitive subjects with a BMI <28 kg/m(2); (2) Group IR comprised nondiabetic, insulin-resistant, obese subjects with a BMI ≥28 kg/m(2); and (3) Group DM comprised patients with manifested T2DM. Retinal microvascular blood flow was assessed using scanning laser doppler flowmetry (Heidelberg Retina Flowmeter) before and after flicker light stimulation (10 Hz; Photo Stimulater 750). No significant difference was observed in retinal blood flow (RBF) among the three groups, neither at baseline nor after stimulating the retina with flicker light. The arterial wall-to-lumen ratio (WLR) tended to be smaller in Group DM compared with Group C, and was significantly lower when comparing Group IR with Group C. When the subjects were grouped according to their insulin resistance, a steady decline in RBF and WLR could be observed with increasing insulin resistance. In conclusion, laser scanner flowmetry of the retina was found to detect very early changes in microvascular blood flow. Development of insulin resistance seems to be an important component in the deterioration of RBF.

Investigation of the effects induced on endothelial function by the human T2238C ANP gene molecular variant

s 153 Clinica Medica, Department of Medical and Surgical Sciences, University of Brescia, Brescia, Italy Clinica Chirurgica, Department of Medical and Surgical Sciences, University of Brescia, Brescia, Italy Chair of Ophthalmology, University of Brescia, Brescia, Italy Chair of Ophthalmology, University of Molise, Campobasso, Italy Chair of Ophthalmology, University of Ferrara, Ferrara, Italy Structural alterations of subcutaneous small resistance arteries, as indicated by an increased media to lumen (M/L) ratio, are frequently present in hypertensive and/or diabetic patients, and may represent the earliest alteration observed. In addition, M/L of small arteries evaluated by micromyography has a strong prognostic significance; however its extensive evaluation is limited by the invasivity of the assessment, since a biopsy of subcutaneous fat is needed. Non-invasive measurement of wall to lumen (W/L) of retinal arterioles using scanning laser doppler flowmetry (SLDF) has been recently introduced (Harazny J et al, Hypertension 2007; 50:623-629). However, this new technique was never compared with micromyographic measurement, considered the gold standard approach. Methods and Results: We have investigated 37 subjects and patients. Twenty-three of them were hypertensives and 14 normotensives. Blood pressure values were 139/88 17/10 mmHg and 125/71 17/12 mm Hg, respectively (p<0.05). All patients underwent a biopsy of subcutaneous fat during an elective surgical intervention. Subcutaneous small resistance arteries were dissected and mounted on a wire myograph, and M/L was measured. In addition, an evaluation of W/L of retinal arterioles by SLDF was performed (Heidelberg Retina Flowmeter, Heidelberg Engineering). A close correlation was observed between M/L of subcutaneous small arteries and WL of retinal arterioles: rZ0.77, p<0.001 (see Figure). Conclusion: A non invasive and easily repeatable procedure (intraobserver and interobserver variation coefficient around 10%) such as an evaluation of the arterioles in the fundus oculi by SDLF may provide similar information regarding microvascular morphology compared in respect with an invasive, accurate and prognostically relevant micromyographic measurement of M/L. y = 6,5298x 0,234 R2 = 0,5902 0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70 0,80 0,04 0,06 0,08 0,10 0,12 0,14 0,16

Reactivity of white blood cell flux to hyperoxia in patients infected with human immunodeficiency virus

The aetiology of the apparently vasoocclusive phenomena in human immunodeficiency virus (HIV)-related retinopathy is not well understood. Several hypotheses, including infectious damage of the retinal vasculature and altered retinal haemodynamics, have been postulated. Direct measurement of oxygen tension in the retina is not possible in vivo and indirect methods have to be employed. The objective of this study was to investigate the retinal vascular response to 100% oxygen breathing in patients with HIV. Twelve patients infected with HIV and 12 healthy individuals, matched for age, sex and smoking habits, were studied in an open study using the blue-field entoptic technique for the measurement of retinal white blood cell (WBC) flux. Reactivity in retinal blood flow during 100% O(2) breathing over 15 min was measured and expressed as percentage change over baseline. WBC velocity during oxygen inhalation decreased over baseline by 9.0 ± 5.8% in HIV-infected patients and by 18.6 ± 5.4% in healthy participants (p < 0.04 between groups, ANOVA). The decrease in WBC velocity was paralleled by a decrease in WBC density. This decrease tended to be more pronounced in healthy participants (13.6 ± 7.9%) than in HIV-infected patients (8.0 ± 10.8%), but the difference was not statistically significant (p = 0.1 between groups, ANOVA). WBC flux decrease was 16.2 ± 11.4% in HIV-infected patients and 29.5 ± 9.5% in the control group and was significant between groups (p = 0.007 between groups, ANOVA). Our results indicate a reduced reactivity of WBC flux to systemic hyperoxia in patients with HIV. Whether abnormal retinal haemodynamics in HIV-infected persons contributes to the pathogenesis of HIV-related microvascular diseases or is a consequence of the structural changes associated with the disease is unknown.

Short-Term Effects ofGinkgo bilobaExtract on Peripapillary Retinal Blood Flow in Normal Tension Glaucoma

PurposeBased on the vascular theory of glaucoma pathogenesis, we wanted to evaluate the effect of Ginkgo biloba extract (GBE) on peripapillary blood flow in patients with normal tension glaucoma (NTG).MethodsThirty patients with NTG were randomly placed in the GBE-treated or control groups. The GBE-treated group received 80 mg GBE orally, twice a day for four weeks, and the control group received a placebo twice a day for four weeks. Complete ocular examinations including visual field, Heidelberg retina flowmeter, and systemic examinations were performed on the first study day and on the day treatment was completed.ResultsAfter GBE treatment, the mean blood flow, volume, and velocity increased at almost all points, and there was a statistically significant increase in blood flow at almost all points, in comparison to the placebo. Blood volume significantly increased only in the superior nasal and superior temporal neuroretinal rim areas. GBE also significantly increased blood velocity in areas of the inferior temporal neuroretinal rim and superior temporal peripapillary area.ConclusionsGBE administration appears to have desirable effect on ocular blood flow in NTG patients.

Effect of Korean Red Ginseng Supplementation on Ocular Blood Flow in Patients with Glaucoma

The purpose of this study was to evaluate the effect of Korean red ginseng (KRG) on ocular blood flow in patients with glaucoma. In a prospective, randomized, placebo-controlled, double-masked crossover trial, 36 patients with open-angle glaucoma were consecutively recruited. Subjects were randomly assigned into two groups. Group A received 1.5 g KRG, administered orally three times daily for 12 weeks, followed by a wash-out period of 8 weeks and 12 weeks of placebo treatment (identical capsules filled with 1.5 g corn starch). Group B underwent the same regimen, but took the placebo first and then KRG. Blood pressure, heart rate, and intraocular pressure were measured at baseline and at the end of each phase of the study. Visual field examination and ocular blood flow measurements by the Heidelberg Retina Flowmeter were performed at baseline and at the end of each phase of the study. Changes in blood pressure, heart rate, intraocular pressure, visual field indices, and retinal peripapillary blood flow were evaluated. Blood pressure, heart rate, intraocular pressure, and visual field indices did not change after placebo or KRG treatment. After KRG treatment, retinal peripapillary blood flow in the temporal peripapillary region significantly improved (p=0.005). No significant changes were found in retinal peripapillary blood flow in either the rim region or the nasal peripapillary region (p=0.051 and 0.278, respectively). KRG ingestion appears to improve retinal peripapillary blood flow in patients with open-angle glaucoma. These results imply that KRG ingestion might be helpful for glaucoma management.

Changes in peripapillary blood flow after intraocular pressure reduction

Abstract Purpose To study retinal blood flow changes after filtration surgery in eyes with normal tension glaucoma (NTG) and exfoliation glaucoma (ExG). Methods Included were one eye of 18 patients with NTG (median age, range; 63 years, 53‐86 years) and 18 with ExG (72 years, 53‐84 years). Deep sclerectomy was performed on all eyes. Temporal peripapillary retinal blood flow was measured with the Heidelberg Retina Flowmeter before and three months after the operation. Automatic full field perfusion image analysis was used and mean flow (MF), peak systolic flow (SF), and minimum diastolic flow (DF) measured, and pulsation index (PI) calculated. Results Intraocular pressure was reduced from 16 mmHg (11‐20 mmHg) to 11 mmHg (3‐20 mmHg) in NTG eyes (p&lt;0.001) and from 24 mmHg (16‐32 mmHg) to 13 mmHg (0‐17 mmHg) in ExG eyes (p&lt;0.001). Preoperatively, in NTG eyes MF (160 AU, 105‐259 AU ) and SF (207 AU, 143‐324 AU) were significantly lower compared with ExG eyes (186 AU, 112‐433 AU, p=0.039; and 261 AU, 180‐513 AU, p=0.024). The difference in DF was of borderline significance. Postoperatively, in ExG MF and SF were significantly reduced (157 AU, 111‐227 AU, p= 0.044; and 213 AU, 146‐291 AU, p=0.017). In NTG eyes there was no significant change in flow. The difference in flow between NTG and ExG eyes was no longer significant. Conclusion A reduced flow in NTG was detected compared with ExG preoperatively. A reduction in IOP resulted in lower peripapillary flow in ExG but no change in flow in NTG.

Altered temporal peripapillary retinal flow in patients with disc hemorrhages

To investigate whether any peripapillary retinal blood flow changes are related to disc hemorrhage (DH). The study included 21 eyes of 21 patients, of which 14 eyes had glaucoma. All eyes were examined at the time of detection of DH and again 6 months later. Blood flow in the peripapillary retina was measured by scanning laser Doppler flowmetry (Heidelberg Retina Flowmeter), with four adjacent images focused on the peripapillary nerve fiber layer obtained. Retinal perfusion was calculated in arbitrary units by automatic full-field perfusion image analysis. The mean of all four rectangles representing the whole temporal peripapillary retina plus the rectangle representing the area of DH served for analysis. The mean of measurements in all four areas revealed a statistically significant increase in mean flow (MF), systolic flow (SF), and diastolic flow (DF), and a decrease in pulsation index (PI). The rectangle representing the area of DH showed a significant increase in MF, but the SF increase was of borderline significance. Changes in DF and PI did not reach statistical significance. Results indicate reduced flow at the time of DH and increased flow after resorption.

PHOTODYNAMIC EFFECTS ON RETINAL OXYGEN SATURATION, BLOOD FLOW, AND ELECTROPHYSIOLOGICAL FUNCTION IN PATIENTS WITH NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

To evaluate the effect of photodynamic therapy (PDT) on retinal functions, such as oxygen saturation, blood flow, and electrophysiological function using Fourier transform-based spectral retinal imaging (SRI), Heidelberg retinal flowmeter (HRF), and multifocal electroretinogram (mfERG). This was a prospective interventional case series. Twenty-two patients with age-related macular degeneration (AMD) with unilateral choroidal neovascularization (CNV) were examined using SRI, HRF, and mfERG before and 1 week and 1 month after PDT. Eleven fellow eyes without CNV and 11 control eyes of 11 age-matched healthy volunteers were also investigated. Eleven of 22 patients with neovascular AMD were retreated using verteporfin PDT and examined using a protocol similar to the one used for the first treatment. Oxygen saturation levels in the macula of eyes with neovascular AMD were significantly higher than those in normal control eyes (P = 0.026) but were not significantly higher in eyes with nonneovascular AMD. Oxygen saturation levels decreased 1 week after a single treatment (P = 4.59 x 10(-3)) and retreatment (P = 0.0134) and recovered to baseline levels at 1 month follow-up (P > 0.05). HRF demonstrated reduced mean blood flow at 1 week after single treatment (P = 9.22 x 10(-4)) and retreatment (P = 0.0307). One month after PDT, mean blood flow tended to show recovery. There was a similar decrease in mfERG amplitude 1 week after treatment, but the logarithm of minimum angular resolution (logMAR) vision was stable or improved throughout follow-up. Oxygen saturation levels, mean blood flow, and mfERG amplitude decreased 1 week after PDT treatment in both single treatment and retreatment groups. Although logMAR vision is stable or improved, our data showed transient functional deterioration in the retina after PDT treatment.

Interobserver Repeatability of Heidelberg Retinal Flowmetry Using Pixel-by-Pixel Analysis

To determine the interobserver reproducibility of Heidelberg retinal flowmeter (HRF) blood flow measurements using independently selected study areas for pixel-by-pixel analysis. Blood flow measurements were performed on 257 scans from 15 patients, 14 of whom had glaucoma or ocular hypertension. HRF was used to record capillary perfusion in a 2560x640 mum area of the supratemporal peripapillary region and pixel-by-pixel analysis was performed from an area adjacent to the optic disc with a minimum of 1600 pixels. Each observer independently selected the area for analysis. The percentage of pixels with <1 arbitrary unit of flow (no flow) and 10, 25, 50, 75, and 90th percentiles of flow values was calculated. Interobserver variability was assessed by estimating the intraclass correlation coefficient (ICC) and its 95% confidence interval. Bland-Altman plots of the difference between the 2 physicians versus the average of the 2 physicians for each outcome were created. ICC was 0.79 (range: 0.74 to 0.83) for mean flow values. For 0, 10, 25, 50, 75, and 90th percentiles of flow, the ICC was 0.67 (0.60 to 0.73), 0.74 (0.68 to 0.79), 0.82 (0.78 to 0.86), 0.85 (0.82 to 0.88), 0.85 (0.81 to 0.88), and 0.77 (0.72 to 0.82), respectively. Zero flow pixels had a nonsignificant mean difference between observers (P=0.542), whereas the remainder of the flow values demonstrated significant mean differences. This study demonstrates that independent observers can review high-quality HRF scans and may produce different absolute values while retaining strong consistency of agreement when independently selecting areas for analysis using the pixel-by-pixel method.

Effect of vitrectomy on macular microcirculation in patients with diffuse diabetic macular edema

To determine whether retinal microcirculatory changes occur after vitrectomy in eyes with diffuse diabetic macular edema (DME), and whether changes in blood flow are associated with visual outcome and the resolution of macular edema. Thirty-three eyes of 30 consecutive diabetic patients who underwent pars plana vitrectomy for diffuse DME, and 16 eyes of 16 diabetic patients without macular edema, were included. Mean macular blood flows were measured using a Heidelberg Retinal Flowmeter, and central macular thicknesses (CMTs) were determined by optical coherence tomography. Visual outcomes, CMTs, and macular blood flow were evaluated before and 1, 4, 12 weeks after vitrectomy, and compared between eyes with resolved macular edema and those with persistent macular edema. Mean preoperative macular blood flow in eyes with diffuse DME was higher than in controls (606.5+/-357.9 AU vs 407.1+/-265.9 AU, P=0.021). Mean macular blood flow (422.6+/-247.5 AU) at 12 weeks after vitrectomy was significantly lower than preoperative blood flow (P=0.002), and similar to that of controls (P=0.47). In 22 of the 33 (66.7%) DME eyes, macular edema was resolved at 12 weeks after vitrectomy. The mean ratio of macular blood flow at 12 weeks postoperatively versus the preoperative level was significantly lower in eyes with resolved macular edema than in eyes with persistent macular edema (0.65 vs 1.08, P<0.001). Increased macular blood flow in diabetic macular edema was normalized after vitrectomy in eyes with resolved macular edema. Changes of macular blood flow may be associated with the resolution of macular edema in diabetic eyes.