Kay Oliver Arend

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.

Retrobulbar haemodynamics in non-arteritic anterior ischaemic optic neuropathy

Aim: To compare retrobulbar haemodynamics in patients with acute non-arteritic anterior ischaemic optic neuropathy (NAION) and age-matched controls by colour Doppler imaging (CDI). Methods: 25 patients with acute NAION and 35 age-matched controls participated in this study. By means of CDI, the blood flow velocities of the ophthalmic artery, central retinal artery (CRA), and nasal and temporal short posterior ciliary arteries (PCAs) were measured. Peak-systolic velocity (PSV) and end-diastolic velocity (EDV) and Pourcelot’s resistive index were determined. Results: In the ophthalmic artery, no marked differences between patients with NAION and controls were detected. PSV and EDV of the CRA (p<0.001, p = 0.002) and PSV of the nasal PCA (p<0.05) were significantly decreased in patients with NAION compared with healthy controls. No marked differences between patients and controls were detectable for temporal PCAs. Conclusion: Blood flow velocities of the nasal PCA and the CRA are considerably reduced in patients with acute NAION compared with controls. Patients with NAION in part showed markedly different retrobulbar haemodynamics.

Optic Disc Fluorescein Leakage and Intraocular Pressure in Primary Open-Angle Glaucoma

Purpose: To investigate the relationship between increased fluorescein leakage of the optic nerve head and intraocular pressure (IOP), visual field defect, vertical cup-to-disc ratio, disc size and systemic blood pressure in primary open-angle glaucoma (POAG). Methods: Twenty-seven patients with POAG (aged 63 ± 11 years) and 15 control subjects (aged 58 ± 9 years, p = 0.14) were included in a pilot study. Fluorescein angiography was performed using a Scanning Laser Ophthalmoscope (Rodenstock Instruments, Germany). Fluorescein leakage of the optic disc was quantified using digital image analysis. The change of optic disc fluorescence from 7–8 min to 9–10 min was calculated and correlated to IOP, visual field mean deviation (MD), vertical cup-to-disc ratio, disc size, mean arterial blood pressure (MAP) and ocular perfusion pressure. Results: The change in optic disc fluorescein leakage was significantly increased in patients with POAG compared to control subjects (POAG: 9.7 ± 6.7%; controls: 3.4 ± 4.9%, p = 0.0025). In POAG, fluorescein leakage was significantly correlated to IOP (r = 0.42, p = 0.029), but not to MD (r = −0.13, p = 0.51), vertical cup-to-disc ratio (r = 0.11, p = 0.60) disc size (r = −0.22, p = 0.30), MAP (r = −0.16, p = 0.42) or ocular perfusion pressure (r = −0.32, p = 0.10). In control subjects, a significant correlation was found with vertical cup-to-disc ratios (r = 0.59, p = 0.034), but not to IOP (r = −0.07, p = 0.80), MD (r = −0.26, p = 0.42), disc size (r = −0.10, p = 0.76), MAP (r = 0.09, p = 0.77), or ocular perfusion pressure (r = 0.11, p = 0.72). Conclusion: Increased fluorescein leakage of the optic disc was associated with higher IOP levels in patients with POAG. This might reflect a link between vascular damage with increased permeability and uncontrolled IOP.

Fluorescein leakage of the optic disc: time course in primary open‐angle glaucoma

Purpose:  To identify and quantify the time course of fluorescein leakage of the optic nerve head in primary open‐angle glaucoma (POAG) and controls.

Arteriovenous Passage Times and Visual Field Progression in Normal Tension Glaucoma

Purpose. Fluorescein angiographic studies revealed prolonged arteriovenous passage (AVP) times and increased fluorescein filling defects in normal tension glaucoma (NTG) compared to healthy controls. The purpose of this study was to correlate baseline AVP and fluorescein filling defects with visual field progression in patients with NTG. Patients and Methods. Patients with a follow-up period of at least 3 years and at least 4 visual field examinations were included in this retrospective study. Fluorescein angiography was performed at baseline using a confocal scanning laser ophthalmoscope (SLO, Rodenstock Instr.); fluorescein filling defects and AVP were measured by digital image analysis and dye dilution curves (25 Hz). Visual field progression was evaluated using regression analysis of the MD (Humphrey-Zeiss, SITA-24-2, MD progression per year (dB/year)). 72 patients with NTG were included, 44 patients in study 1 (fluorescein filling defects) and 28 patients in study 2 (AVP). Results. In study 1 (mean follow-up 6.6 ± 1.9 years, 10 ± 5 visual field tests), MD progression per year (−0.51 ± 0.59 dB/year) was significantly correlated to the age (P = 0.04, r = -0.29) but not to fluorescein filling defects, IOP, or MD at baseline. In study 2 (mean follow-up 6.6 ± 2.2 years, 10 ± 5 visual field tests), MD progression per year (−0.45 ± 0.51 dB/year) was significantly correlated to AVP (P = 0.03, r = 0.39) but not to age, IOP, or MD at baseline. Conclusion. Longer AVP times at baseline are correlated to visual field progression in NTG. Impaired retinal blood flow seems to be an important factor for glaucoma progression.

Sensitivity of imaging the peripheral nerve fibre layer using a confocal scanning laser ophthalmoscope to detect glaucoma

PURPOSE The aim of this study was to evaluate the sensitivity to detect glaucoma by observer-dependent nerve fibre layer imaging and evaluation using a scanning laser ophthalmoscope. PATIENTS AND METHODS Fifty-four patients with primary open angle glaucoma (POAG), 41 patients with normal tension glaucoma (NTG) and 65 eyes of control subjects were included in a retrospective study. Nerve fibre layer imaging was performed using a confocal scanning laser ophthalmoscope (SLO, Rodenstock Instr., argon laser 488 nm). Digitised images of the nerve fibre layer were graded off-line by two masked experienced observers. The nerve fibre layer was graded for every single degree (defect or no defect) at 1.7 and 3.4 mm distance to the optic nerve head omitting the nasal 110 degrees. Sensitivity and specificity levels were calculated using ROC analysis. RESULTS Patients with POAG exhibited nerve fibre layer defects of 100 degrees +/- 94 degrees (1.7 mm and 3.4 mm distance) and patients with NTG of 94 degrees +/- 94 degrees (1.7 mm distance) and 103 degrees +/- 92 degrees (3.4 mm distance), significantly larger compared to controls (1 degrees +/- 3 degrees [1.7 mm, p < 0.0001] and 1 degrees +/- 4 degrees [3.4 mm, p < 0.0001]). Sensitivity at > 90 % specificity was 80 % (1.7 mm) and 82 % (3.4 mm) for POAG. In NTG, sensitivity at > 90 % specifity was 81 % (1.7 mm) and 85 % (3.4 mm). In early glaucoma (MD < -6 dB, n = 39) sensitivity decreased to 75 % (1.7 mm) and 81 % (3.4 mm). CONCLUSION Observer-dependent evaluation and grading of the nerve fibre layer using a scanning laser ophthalmoscope reaches considerably high sensitivity levels to detect glaucoma with negligible differences between the central and peripheral regions.

Potential diagnostic value of fluorescein angiography and color Doppler imaging in primary open-angle glaucoma.

We read with interest the article “Potential diagnostic value of fluorescein angiography and color Doppler imaging in primary open-angle glaucoma” by Mokbel and colleagues (1), and compare it to our previous publications (2, 3). The authors measured absolute fluorescein filling defects of the optic disc in primary open-angle glaucoma and compared the extent of the filling defects with retrobulbar blood flow velocities measured by color Doppler imaging. A correlation was found for end-diastolic velocities and resistive indices of retrobulbar vessels with the areas of superficial capillary rarefaction as seen in fluorescein angiography. Our study, published in 2003 (2), described results for patients with normal tension glaucoma, and found comparable results. We agree with the authors that downstream resistance of the central retinal artery and short posterior ciliary arteries seems to be an important factor of the circulatory disturbance of the optic nerve in glaucoma. A major concern, however, is related to the data presented by the authors on absolute filling defects. Mokbel et al measured absolute filling defects of 29.0350% (median) in their control group. Previous published studies on this topic have shown that in healthy subjects, filling defects are typically not found, or only very small defects can be detected (4, 5). The large value reported is in contrast to all previous studies, as filling defects are highly specific for glaucoma. We have studied absolute filling defects in glaucoma for more than 15 years using confocal scanning laser ophthalmoscopy. It is crucial in visualizing capillary rarefaction of the optic disc to avoid artefacts due to defocus and to ensure highest image quality. The authors present data on color Doppler imaging on retrobulbar vessels with high diagnostic accuracy. This again is contradictory to previous published studies (6). In such a study, the most important factor in avoiding bias in color Doppler imaging measurements is that the operator is masked with respect to the diagnosis of the study subjects. The measurement of end-diastolic velocities is especially susceptible to a systemic error due to unmasked operators. In addition, the reported peak systolic velocities in the short posterior ciliary arteries are much higher compared to previous studies. The measurements of short posterior ciliary arteries are more difficult than any other retrobulbar vessel. The high flow velocities in the presented study are most likely to be related to long posterior ciliary arteries. In our previously published study on the sensitivity and specificity of retrobulbar flow velocity measurements (6), the end-diastolic velocity of the central retinal artery is indeed the parameter with the highest sensitivity, albeit being as low as 48% at 90% specificity. We are convinced that the main topic, vascular damage in glaucoma as seen by fluorescein angiography and color Doppler imaging, remains crucial in further understanding the pathology of glaucomatous optic neuropathy. However, a detailed interpretation of the data shown by Mokbel et al is highly difficult as the actual values differ greatly from previous published reports.

Acute Effect of Hypervolemic Hemodilution on Retrobulbar Hemodynamics in Anterior Ischemic Optic Neuropathy

Purpose Ischemic ocular disorders may be treated by hypervolemic hemodilution. The presumed therapeutic benefit is based on a volume effect and improved rheological factors. The aim was to investigate the acute effect of intravenous hydroxyethyl starch on retrobulbar hemodynamics in patients with nonarteritic anterior ischemic optic neuropathy (NAION). Methods 24 patients with acute NAION were included. Retrobulbar hemodynamics were measured using color Doppler imaging before and 15 min after intravenous infusion of 250 cc 10% hydroxyethyl starch (HES). Peak systolic velocity (PSV), end diastolic velocity (EDV), and Pourcelots resistive index (RI) were measured in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (PCAs). Results After infusion of HES blood flow velocities significantly increased in the CRA (PSV from 7.53 ± 2.33 to 8.32 ± 2.51  (p < 0.001); EDV from 2.16 ± 0.56 to 2.34 ± 0.55  (p < 0.05)) and in the PCAs (PSV from 7.18 ± 1.62 to 7.56 ± 1.55  (p < 0.01); EDV from 2.48 ± 0.55 to 2.66 ± 0.6 cm/sec (p < 0.01)). The RI of all retrobulbar vessels remained unaffected. Blood pressure and heart rate remained unchanged. Conclusions Hypervolemic hemodilution has an acute effect on blood flow velocities in the CRA and PCAs in NAION patients. Increased blood flow in the arteries supplying the optic nerve head may lead to a better perfusion in NAION patients. This trial is registered with DRKS00012603.