A. Remky

Colour Doppler imaging and fluorescein filling defects of the optic disc in normal tension glaucoma

Aim: To investigate the relation between blood flow parameters of the retrobulbar vessels measured by means of colour Doppler imaging (CDI) and fluorescein filling defects of the optic nerve head in patients with normal tension glaucoma (NTG) and control subjects. Methods: 29 patients with NTG and 29 age and sex matched control subjects were included in this study. Blood flow velocities—peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive indices (RI) of the ophthalmic artery (OA), the central retinal artery (CRA), and of the temporal and nasal short posterior ciliary arteries (TPCA, NPCA)—were measured with CDI. Fluorescein angiograms were performed with a scanning laser ophthalmoscope. The extent of absolute fluorescein filling defects of the optic nerve head in relation to the optic nerve head was assessed. Results: The PSV of the OA, the PSV and EDV of the CRA, and of the TPCA and NPCA were significantly reduced in NTG (p<0.05). The RI of the CRA, the TPCA and NPCA were significantly increased in NTG (p<0.01). The optic nerve head fluorescein filling defects were significantly larger in NTG (p<0.01). The filling defects were significantly negatively correlated (p<0.05) with the PSV and EDV of the CRA (PSVCRA: r = −0.41; EDVCRA: r = −0.34), with the PSV and EDV of the NPCA (PSVNPCA: r = −0.34; EDVNPCA: r = −0.38), and with the EDV of the TPCA (r = −0.29). A significant positive correlation (p<0.05) was found with the RI of both PCAs (RINPCA: r = 0.28; RITPCA: r = 0.29). Conclusion: Patients with NTG had reduced blood flow velocities and higher resistive indices in most retrobulbar vessels. Optic nerve head fluorescein filling defects were larger compared to controls. The filling defects were correlated with end diastolic velocities and resistive indices of the PCAs and with blood flow velocities of the CRA. Capillary loss of the optic nerve head may be related to higher downstream resistance and reduced blood flow velocities of the retrobulbar vessels.

Perifoveal microcirculation with non-insulin-dependent diabetes mellitus

Fluorescein angiograms were performed to evaluate perifoveal capillary blood velocities (v), capillary density (perifoveal intercapillary areas: PIA) and the foveal avascular zone (FAZ) by means of the scanning laser technique (SLO-101 Rodenstock). The angiograms were digitally stored and the data quantified off-line with an image analyzing system (IBAS). In the present study 46 patients with non-insulin-dependent diabetes mellitus (NIDDM) were examined and their data compared with that of 31 healthy volunteers. The perifoveal capillary flow velocity of the NIDDM subjects (v = 2.33±0.36 mm/s) was significantly (P <0.01) decreased as compared to healthy subjects (v = 2.86 ±0.41 mm/s). The perifoveal intercapillary areas in the foveal avascular zone were significantly increased in patients with NIDDM (PIA=10029 ± 3402 μm2; FAZ = 0.415 ± 0.272 mm2) as compared with healthy subjects (PIA = 3965 ± 467 μm2; FAZ=0.221 ± 0.071 mm2). These data suggest the possibility that a decrease in perifoveal capillary blood velocities in combination with decreased capillary density (enlarged PIA) and an enlargement of the foveal avascular zone may occur in patients with NIDDM. The determination of these parameters could help in monitoring the progress of diabetic retinopathy and diabetic maculopathy.

Capillary density and retinal diameter measurements and their impact on altered retinal circulation in glaucoma: A digital fluorescein angiographic study

Aim: Normal pressure glaucoma (NPG) patients exhibit prolonged retinal arteriovenous passage times in fluorescein angiography and colour Doppler imaging suggests increased resistance downstream from the central retinal and posterior ciliary arteries. The aim of the study was to elucidate the morphological source of decreased perfusion and increased resistance of the ocular circulation in NPG. Methods: Retinal arteriovenous passage time (AVP) and peripapillary arterial and venous diameters were measured in digital scanning laser fluorescein angiograms. For estimation of retinal capillary density the area of the foveal avascular zone (FAZ) and the perifoveal intercapillary area (PIA) was quantified. 36 patients with NPG (mean age 57 (SD 13) years) and 21 healthy subjects (mean age 51 (13) years) were enrolled in the comparative study. Results: In NPG patients the AVP (2.55 (1.1) seconds) was significantly prolonged (p<0.001) when compared with healthy subject data (AVP: 1.70 (0.39) seconds). No differences for arterial or venous diameter, FAZ, and PIA were observed in NPG patients compared with healthy subjects. FAZ, PIA, arterial and venous diameter were not correlated with visual field indices (except venous diameter with PSD, r=0.35 (p<0.05)) or cup to disc ratios. AVP was significantly correlated (p<0.05) with the size of the optic nerve head (r=−0.28), visual field indices (MD: r=−0.3; PSD: r=0.3; CPSD: r=0.3), and contrast sensitivity (r=−0.34}. Conclusion: AVP times are significantly prolonged in NPG. The slowing of the retinal transit does not result from capillary dropout, or changes of peripapillary arterial or venous diameters with increased vascular resistance.

Altitudinal visual field asymmetry is coupled with altered retinal circulation in patients with normal pressure glaucoma

AIM To compare the effect of altitudinal asymmetric glaucomatous damage on retinal microcirculation in patients with normal pressure glaucoma (NPG). METHODS In a prospective cross sectional study patients with NPG (washed out for antiglaucomatous therapy) and altitudinal asymmetric perimetric findings between the superior and inferior hemisphere (Humphrey 24–2) (n=18) were included and compared with 20 NPG patients with symmetrical field defects and 18 healthy subjects. Fluorescein angiograms were performed using a scanning laser ophthalmoscope. Using digital image analysis, arteriovenous passage time (AVP) and vessel diameters were assessed for comparison of corresponding affected and less affected temporal arcades. RESULTS Both affected and less affected hemispheres showed significantly prolonged AVP times (p<0.001) when compared with healthy subject data. In hemispheres with more severe glaucomatous field loss the AVP times were significantly (p=0.04) prolonged compared with the less affected hemisphere (AVP affected 3.1 (SD 7) seconds v AVP less affected 2.61 (1.4) seconds). There was no asymmetry effect on arterial and venous diameter measurements. CONCLUSION Altitudinal visual field defects are linked together with circulatory deficits of the retinal tissue. The attenuated circulation seems to be a considerable factor in the natural course of glaucomatous optic neuropathy.

Macular capillary particle velocities: a blue field and scanning laser comparison

Abstract• Background: Two different techniques are available for measurement of macular capillary particle velocities. The psychophysical blue field simulation technique gives data on macular leukocyte flow velocities, while the scanning laser technique provides information on capillary blood velocities of hypofluorescent segments in the macular network. Published velocity data differ considerably between the two methods. The current study was undertaken to compare the two measuring techniques in a group of healthy volunteers. • Methods: Thirty-two healthy subjects (12 man, 20 women, mean age 27 years) participated in this study. All subjects underwent entoptic leukocyte visualization by means of blue field simulation followed by fluorescein angiography using scanning laser ophthalmoscopy. • Results: The capillary blood velocities measured using the scanning laser technique were significantly higher (P < 0.01) than the flow velocities estimated with the blue field simulation technique (2.68 ± 0.3 mm/s vs 0.89 ±0.2 mm/s). No significant correlation between the flow velocities was found (r = −0.22). • Conclusion: The differences may be related to different measuring locations and/or measurements of different phenomena. The blue field technique estimates average leukocyte flow in the macular network, whereas the scanning laser technique quantifies the velocity of erythrocyte aggregates in the capillary lumen of the para- and perifoveal network. A combination of both techniques may be helpful in interpreting physiological responsiveness and altered velocity pattern in diseased eyes.

Macular microcirculation in cystoid maculopathy of diabetic patients.

BACKGROUND--In patients with diabetic macular oedema and central cysts ischaemia of the retina appears to be an important contributing factor in the pathogenesis of cysts. This study was performed to further elucidate the role of the inner retinal microcirculation in diabetic cystoid macular oedema (CMO). METHODS--Video fluorescein angiography allows visualisation of the macular microvasculature and measurements of the capillary blood velocity (CBV), foveal avascular zone (FAZ), and perifoveal intercapillary area (PIA, characterising capillary density). RESULTS--Twenty three diabetic subjects with CMO, matched diabetic patients without macular oedema (n = 23), and healthy subjects (n = 23) were included. CBV, PIA, and FAZ did not differ significantly among diabetic groups regardless of presence of cystoid changes. CBV was significantly reduced (p < 0.0001) and PIA was more than doubled in both diabetic groups (p < 0.0001) when compared with healthy subjects. Furthermore, FAZ showed a nearly doubled size in diabetic patients without macular oedema (p < 0.01) and a less pronounced enlargement (by 29%) in diabetics with CMO (p < 0.05). CONCLUSION--The results indicate that the retinal microcirculation in diabetic patients is markedly altered when compared with healthy subjects, regardless of CMO presence. In CMO patients the microcirculatory changes are similar to those of diabetic patients without macular oedema. Thus inner retinal perfusion does not contribute to tissue ischaemia leading to cystoid formations in diabetic maculopathy.

Retrobulbar haemodynamics and morphometric optic disc analysis in primary open-angle glaucoma

Background: Previous studies confirmed reduced retrobulbar haemodynamics in primary open-angle glaucoma (POAG). Aim: To investigate a correlation between retrobulbar haemodynamics and morphometric neuroretinal rim analysis in patients with POAG. Methods: 51 patients with POAG (mean (standard deviation (SD)) age 65 (11) years) were included in this clinical study. Blood flow velocities (peak systolic velocity (PSV) and end-diastolic velocity (EDV)) of the ophthalmic artery, central retinal artery (CRA), posterior ciliary arteries (PCA) and central retinal vein were measured using colour Doppler imaging (Siemens Sonoline Sienna, Erlangen, Germany). Optic disc morphometry was carried out using scanning laser tomography (Heidelberg Retinal Tomograph II Heidelberg Egineering Heidelberg, Germany). The stereometric parameters of the neuroretinal rim (rim area, rim volume, cup shape measure and retinal nerve fibre layer (RNFL) cross-sectional area) were used for analysis. Results: The PSV of the CRA was significantly (p<0.001) correlated with rim area (r = 0.50) and rim volume (r = 0.51). The minimum velocities of the central retinal vein were significantly (p<0.001) correlated with rim volume (r = 0.56) and RNFL cross-sectional area (r = 0.49). No correlations were found for the flow velocities of the ophthalmic artery and PCAs. Conclusion: Retrobulbar haemodynamics of the central retinal artery and vein are correlated with the neuroretinal rim damage in POAG.

Short-wavelength automated perimetry in patients with diabetes mellitus without macular edema

BackgroundThe short-wavelength-sensitive (SWS) cone-mediated sensitivity is a sensitive indicator of functional changes of the macula in diabetic maculopathy. This study was performed to investigate whether functional losses of the macula are detectable in patients without a significant macular edema.MethodsIn 45 patients with diabetes mellitus with clear optical media and no macular edema, conventional white-on-white perimetry (WWP) and short-wavelength automated perimetry (SWAP) were performed in the central 10-deg field. Fifty-eight healthy subjects ranging in age from 16 to 62 years served as controls. The two groups did not differ in age.ResultsVariance analysis (ANOVA) revealed significantly lower sensitivity in patients with diabetes than in controls. SWAP thresholds were significantly more greatly reduced by diabetes than those of WWP (ANOVA interaction: P=0.003). Post-hoc testing revealed a sensitivity reduction of 2.8 dB (P=0.0003) in patients with diabetes for SWAP versus 0.46 for WWP (P=0.15). Subgroup analysis revealed that mean thresholds of SWAP and WWP predominantly were reduced in patients with advanced disease. In patients with no retinopathy, sensitivity was not affected at all.ConclusionSWS sensitivity may be affected in patients with diabetic retinopathy without clinically significant macular edema. Sensitivity loss was pronounced with increasing severity of retinopathy, reflecting the global status of the eye.

Perifoveal Capillary Network in Patients with Acute Central Retinal Vein Occlusion

PURPOSE Reduction of visual acuity in patients with central retinal vein occlusion (CRVO) is often caused by macular edema and ischemia. The major causative factor for macular changes may be a disturbance in the macular microcirculation. The authors studied the perifoveal microcirculation in patients with central retinal vein occlusion to quantify the extent of circulatory deficiency in the macular circulation. METHODS Twenty-four patients (8 men, 16 women) with recently diagnosed CRVO were included in this study. The following data were quantified: mean capillary blood velocity (CBV), foveal avascular zone (FAZ), and mean perifoveal intercapillary area (PIA). RESULTS In patients with CRVO, the mean flow velocity was significantly reduced compared with healthy subjects (1.63 +/- 0.220 mm/sec vs. 2.89 +/- 0.41 mm/sec, P < 0.01). The FAZ and the mean PIA characterizing capillary density were significantly enlarged in CRVO (5548 +/- 1151 microm2 vs. 3872 +/- 529 microm2; P < 0.01). CONCLUSIONS The present study demonstrates that CRVO not only led to a decrease in capillary blood velocities, but also to an enlargement of perifoveal intercapillary areas in early stages of the disease.

Haemorheology in patients with branch retinal vein occlusion with and without risk factors

Abstract• Purpose: The study was carried out to ascertain the role of blood viscosity in patients with branch retinal vein occlusion (BR-VO) with and without risk factors. • Methods: In 292 patients with acute BRVO (mean age 65 ± 10 years) and 292 controls matched for gender, age, and cardiovascular risk factors, haematocrit, plasma viscosity, erythrocyte aggregation and erythrocyte rigidity were measured. A subgroup analysis in patients with and without risk factors was performed. • Results: Haematocrit and plasma viscosity values were significantly higher in BRVO patients than in controls, but erythrocyte rigidity and erythrocyte aggregaton did not differ. Subgroup analysis revealed no differences in haematocrit and plasma viscosity values between patients with and those without cardioavascular risk factors. • Conclusions: This study shows increased plasma viscosity and haematocrit values in patients with BRVO which are not associated with the presence of other cardiovascular risk factors. Thus, changes in blood fluidity appear to be important factors in the pathogenesis of BRVO.