O Arend

University Hospital RWTH Aachen, Aachen, North Rhine-Westphalia, Germany

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Publications (112)191.13 Total impact

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    ABSTRACT: Purpose: Topical carbonic anhydrase inhibitors such as dorzolamide have been developed as ocular hypotensive agents devoid of the side effects plaguing their systemic predecessors. We evaluated the influence of dorzolamide on retinal and retrobulbar blood flow markers to determine if the drug has orbital vascular as well as ocular hypotensive effects.Methods: Eleven persons with healthy eyes received either placebo or two drops 2% dorzolamide, 2 h prior to studies conducted in double-masked, counterbalanced fashion. Four retrobulbar vessels (nasal and temporal posterior ciliary, central retinal, and ophthalmic arteries) were analyzed by color Doppler imaging; scanning laser ophthalmoscopy was used to examine retinal and superficial optic nerve head blood linear velocity.Results: Dorzolamide lowered IOP from 15.7 ± 0.7 to 13.7 ± 0.7 mmHg (p < 0.05). The drug also hastened retinal arteriovenous passage of fluorescein dye, and accelerated capillary dye transit in the macula and optic nerve head. The drug, however, left unaltered blood velocity or resistance index in any retrobulbar vessel.Conclusions: Dorzolamide is an effective ocular hypotensive agent that accelerates blood velocity in the retinal and superficial optic nerve head without an apparent effect upon retrobulbar hemodynamics.
    Acta Ophthalmologica Scandinavica 05/2009; 74(6):569 - 572. · 1.85 Impact Factor
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    ABSTRACT: To investigate interocular differences in retrobulbar flow velocities in patients with asymmetric glaucomatous visual field loss. Twenty-five patients with primary open-angle glaucoma (POAG) and asymmetric visual field loss were included in this study. Asymmetric visual field loss was defined as a difference of the global index mean deviation (MD) >6 dB between the two eyes. Flow velocities (peak systolic velocity PSV and end-diastolic velocity EDV) and resistive indices (RI) of the ophthalmic artery (OA), central retinal artery (CRA), and nasal and temporal posterior ciliary arteries were measured by means of colour Doppler imaging. MD of eyes with more severe glaucomatous visual field loss was -18.3+/-7.8 dB vs -6.8+/-5.5 dB (p<0.0001) in the less affected eyes. The PSV and the EDV of the CRA and the PSV of the OA were significantly decreased in eyes with more severe glaucomatous visual field loss (CRA PSV: 7.6+/-2.0 cm/s vs 8.3+/-1.7 cm/s, p=0.04; CRA EDV: 2.24+/-0.5 cm/s vs 2.55+/-0.6 cm/s, p<0.007; OA PSV: 29.7+/-9.9 cm/s vs 32.7+/-11.5 cm/s, p<0.02). None of the other differences in velocity or resistive index were significant. Patients with asymmetric glaucomatous visual field loss exhibit asymmetric flow velocities of the CRA and OA. Patients with more severe damage display reduced flow velocities in retrobulbar vessels in POAG.
    Albrecht von Graæes Archiv für Ophthalmologie 09/2006; 244(8):978-83. · 1.93 Impact Factor
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    ABSTRACT: Ocular hemodynamics is of great interest in glaucoma, especially since vascular disturbances may play a pathogenetic role in disease development. To investigate the hemodynamic differences between normal pressure glaucoma patients and normal volunteers, flow velocities of the retrobulbar vessels were measured by colour Doppler imaging. 15 patients with normal pressure glaucoma (NPG) and 15 healthy volunteers underwent colour Doppler imaging (CDI) of the retrobulbar vessels. The patients and the volunteers were especially gender- and age-matched. Peak systolic velocities (PSV), end-diastolic velocities (EDV), and resistive indices (RI) of the ophthalmic artery and central retinal artery were obtained. In NPG patients, PSV and EDV in the central retinal artery were significantly decreased, whereas RI was increased in central retinal artery and the ophthalmic artery. Colour Doppler imaging is a non-invasive technique that allows further estimation of the ocular circulatory status. Particularly in the group of patients with disturbed hemodynamics, like NPG patients, it was able to show a reduction of the retrobulbar hemodynamics.
    Klinische Monatsblätter für Augenheilkunde 03/2006; 223(2):156-60. · 0.70 Impact Factor
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    ABSTRACT: Systemic arterial hypotension, hypertension and altered ocular blood flow are known risk factors in glaucoma. In this study, 24-h ambulatory blood pressure monitoring was performed in patients with normal tension glaucoma (NTG) and controls to evaluate blood pressure variability. In all, 51 patients with NTG and 28 age-matched controls were included in this prospective study. A 24-h ambulatory blood pressure monitoring (SpaceLabs Medical Inc., Redmond, USA) was performed and systolic, diastolic and mean arterial blood pressures were measured every 30 min during daytime (0800-2000) and night time (0000-0600). To evaluate blood pressure variability a variability index was defined as the s.d. of blood pressure measurements. Night-time blood pressure depression ('dip') was calculated (in percent of the daytime blood pressures). Patients with NTG exhibited higher night-time diastolic (P = 0.01) and mean arterial blood pressure values (P = 0.02) compared to controls, whereas systolic blood pressure data were not significantly different. The variability indices of night-time systolic, diastolic and mean arterial blood pressure measurements were significantly increased in patients with NTG compared to controls (P < 0.05). The night-time blood pressure depression of systolic (P = 0.47), diastolic (P = 0.11) and mean arterial blood pressures (P = 0.28) was not significantly different between patients with NTG and controls. In conclusion, patients with NTG showed increased variability of night-time blood pressure measurements compared to controls. Increased fluctuation of blood pressure may lead to ocular perfusion pressure fluctuation and may cause ischaemic episodes at the optic nerve head.
    Journal of Human Hypertension 02/2006; 20(2):137-42. · 2.82 Impact Factor
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    ABSTRACT: During organ culture, corneas swell and have to be de-swollen prior to transplantation using a medium. Both swelling and de-swelling lead to increased endothelial cell loss. Furthermore, dextran, the standard de-swelling substance, is toxic and deposited in the cornea. Whether HES is suitable as a continuous supplement for organ culture and keeps the corneas thin was investigated in this study. Forty-five human corneas were stored in MEM plus 7.5% HES 130 for 7, 15, 21, and 28 days. Endothelial cell count was determined before and after organ culture. After storage the water content and amount of adenosine phosphates were measured. Water content was 82.29% after 7 days, 82.98% after 15 days, 81.15% after 21 days, and 83.21% after 28 days. The endothelial cell count decreased by 1.20% after 7 days, 0.60% after 15 days, 4.29% after 21 days, and 6.89% after 28 days. ATP was 0.159 micromol/g dry weight after 28 days of organ culture. The water content of corneas stored in HES-containing medium remained constant even after 21 days of organ culture. Endothelial cell loss was less than in comparable studies using a standard medium containing 10% FCS; however, ATP concentrations were worse. HES 130 keeps the corneas thin and can be used as a continuous supplement. It facilitates the handling of corneas during organ culture, making dehydration before transplantation unnecessary, and thus also reduces potential stress factors for the cornea.
    Der Ophthalmologe 02/2006; 103(1):43-7. · 0.53 Impact Factor
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    ABSTRACT: To evaluate fluorescein filling defects of the optic nerve head in normal tension glaucoma (NTG), primary open-angle glaucoma (POAG), ocular hypertension (OHT) and controls. Forty patients with NTG (mean age 55 +/- 10 years), 40 patients with POAG (mean age 55 +/- 11 years), 40 patients with OHT (mean age 53 +/- 13 years), and 40 age-matched controls (mean age 54 +/- 11 years) were included in a prospective study. Video fluorescein angiograms were performed by means of a scanning laser ophthalmoscope. The extent of absolute filling defects of the optic nerve head was assessed (as a percentage of the disc area) using digital image analysis. Visual fields were tested by automatic static perimetry (Humphrey Field Analyzer, programme 24-2). Absolute filling defects were significantly larger in patients with NTG (12.2 +/- 15.5%) and POAG (12.9 +/- 13.1%) compared to patients with OHT (1.2 +/- 3.6%) and healthy controls (0.1 +/- 0.5%) (p < 0.0001). The area under the receiver operating characteristic (ROC) curve was 0.806 for NTG vs healthy controls, and 0.812 for POAG vs OHT. Absolute filling defects are significantly correlated to the global indices mean deviation (r = -0.63, p < 0.0001), pattern standard deviation (r = 0.61, p < 0.0001), and corrected pattern standard deviation (r = 0.62, p < 0.0001) and significantly correlated to horizontal (r = 0.50, p < 0.0001) and vertical (r = 0.53, p < 0.0001) cup-to-disc-ratios. Fluorescein filling defects of the optic disc representing capillary dropout are present in NTG and POAG. The extent of these filling defects is correlated to visual field loss and morphological damage. Fluorescein angiography may be useful in the diagnosis and management of NTG and POAG.
    Ophthalmic and Physiological Optics 01/2006; 26(1):26-32. · 1.74 Impact Factor
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    ABSTRACT: To identify and quantify the role of capillary leakage of the optic nerve head in digital fluorescein angiography in normal subjects and patients with open-angle glaucoma. We conducted a prospective cross-sectional study in the Department of Ophthalmology of the Technical University of Aachen. Thirty patients with primary open-angle glaucoma (POAG) and 30 healthy age-matched subjects were included. Fluorescein angiograms were performed using the scanning laser ophthalmoscope. The fluorescence of the optic nerve head and the surrounding retina (ratio of leakage) was measured using digital imaging analysis in the late phases of the angiogram (9-10 min). The ratio of optic nerve head fluorescence to retinal reference loci was significantly increased (p=0.01) in patients with glaucoma (POAG, 1.38+/-0.34) compared with normal subjects (1.20+/-0.19). Intraocular pressure (p=0.0001), visual field indices (mean deviation, p<0.0001; pattern standard deviation, p<0.0001; corrected pattern standard deviation, p<0.0001), and cup to disc ratios (p=0.02) differed significantly between the groups. Age and systolic and diastolic blood pressure showed no significant differences between groups. Fluorescein angiography revealed significantly increased vascular leakage of glaucomatous optic nerve heads. An endothelial disruption and fluorescein leakage might be the result of mechanical stress at the level of the lamina cribrosa and/or a sign of ischemic damage. This measurement approach might enable us to judge the severity of optic nerve head leakage, and it is a potential way to evaluate therapeutic regimens.
    Albrecht von Graæes Archiv für Ophthalmologie 08/2005; 243(7):659-64. · 1.93 Impact Factor
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    ABSTRACT: Numerous studies have confirmed the enhancement of ocular circulation by carbonic anhydrase inhibitors (CAIs). Topical CAI treatment with dorzolamide averts the significant pericentral visual function loss accompanying retinal and choroidal vasoconstriction during acute hyperventilation-induced hypocapnia. This study was designed to discern whether dorzolamide might similarly enhance macular function in patients with age-related maculopathy (ARM). In a masked, placebo-controlled study, 40 patients with ARM and acuity > 20/50 were randomized to receive either dorzolamide or placebo for 12 weeks, thrice daily. After pre-study perimetric training, pericentral function (mean sensitivity) was quantified using Humphrey 10-2 short-wavelength automated perimetry (SWAP), before and after 12 weeks of topical therapy. Dorzolamide-treated eyes demonstrated a significant increase in mean sensitivity of + 1.55 dB (p = 0.04); placebo-treated eyes showed no significant change (+ 0.58 dB; p = 0.10). Given the non-significant increase of mean sensitivity in the placebo-treated group, fewer than 100 subjects per group would be required to afford > 70% power to yield a significant direct comparative difference between treatment and placebo in a prospective, randomized study of equally short duration. This study demonstrated a significant increase in short-wavelength sensitivity in ARM with dorzolamide and the lack thereof with placebo. These encouraging pilot study data suggest a potential role for topical CAIs in ARM patients, and establish objective parameters for prospective studies to further evaluate the effects of dorzolamide in ARM.
    Acta Ophthalmologica Scandinavica 04/2005; 83(2):154-60. · 1.85 Impact Factor
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    ABSTRACT: Excessively draining fistulas may lead to enucleation when primary suture closure is not effective. In these cases preserved cadaver tissues such as sclera, fascia lata, dura mater and peritoneum have been used for patch graft repair with variable results. In this study, the clinical outcomes after transplantation of scleral patch grafts have been investigated. Twenty-eight eyes of twenty-seven patients underwent surgery with homologous scleral patch grafts for repair of excessively draining scleral fistulas after cataract surgery (n = 2), leaking filtering blebs following full-thickness filtration surgery (n = 7), large scleral perforations due to trauma (n = 7), corneo-scleral ulcerations due to severe eye burns (n = 9) or after radiotherapy of malignant melanoma (n = 3). The mean size of the rectangular grafts was 8.6 x 6.7 mm (+/- 2.8/3.1 mm). Clinical follow-up was up to 73 months (median 30 months). Twenty-three of 28 eyes (82.1 %) showed functional closure after initial surgery without any wound complication such as patch retraction or leakage and without evidence of inflammation. In five eyes surgical revision was necessary. Two of these eyes had to be enucleated due to uncontrollable dehiscence after the second operation. Two eyes were enucleated at the patient's demand due to pain. The fifth eye showed effective closure after the second operation. In our study scleral patch grafts were useful in adequately closing large corneo-scleral defects in 24 of 28 eyes (85.7 %). The antigen load and, therefore, the rejection of the scleral grafts is minimized due to the denaturation of proteins during the alcohol treatment before storage.
    Klinische Monatsblätter für Augenheilkunde 11/2004; 221(10):867-71. · 0.70 Impact Factor
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    K Huber, N Plange, A Remky, O Arend
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    ABSTRACT: To correlate retinal circulatory measurements using scanning laser fluorescein angiography and flow velocities of retrobulbar vessels measured by means of colour Doppler imaging. Fifteen patients with normal pressure glaucoma (NPG) and 15 healthy volunteers underwent colour Doppler imaging and fluorescein angiographic studies. Peak systolic velocities (PSVs), end-diastolic velocities (EDVs) and resistive indices (RIs) of the ophthalmic artery (OA) and central retinal artery were obtained. In the fluorescein angiograms arteriovenous passage time (AVP) was quantified by means of digital dye dilution curve analysis. Arteriovenous passage time was significantly prolonged in NPG patients compared to healthy subjects (p = 0.0026). In the central retinal artery PSV (p = 0.023) and EDV (p < 0.0001) were significantly decreased and RI was increased (p < 0.0001) in patients with NPG. The EDV of the central retinal artery showed a significant correlation with AVP (EDV: r = - 0.53, p = 0.0023). The RI of the central retinal artery correlated significantly to AVP (RI: r = 0.63, p < 0.0001). The AVP did not correlate to EDV or PSV, nor to the RI measured in the ophthalmic artery. Arteriovenous passage time, which represents blood flow in a vascular segment of artery, capillary bed and corresponding vein, was found to be correlated to the EDV and the RI of the central retinal artery. The combination of different techniques allows further interpretation of ocular circulatory responses.
    Acta Ophthalmologica Scandinavica 09/2004; 82(4):426-31. · 1.85 Impact Factor
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    ABSTRACT: To identify and quantify the role of retinal circulation, capillary leakage and/or nonperfusion of the optic nerve head in digital fluorescein angiography in normal subjects and patients with open angle glaucoma. Eighteen patients with primary open angle glaucoma (POAG) and 18 healthy age matched subjects were included. Fluorescein angiograms were performed using the scanning laser ophthalmoscope. The arteriovenous passage time (AVP) was assessed by dye dilution technique and describes the shortest passage through a retinal vascular segment. Optic nerve head nonperfusion was marked manually in early angiographic images and is given as percentage of the optic disk area. The fluorescence of the optic nerve head (as measure of the disruption of the blood-brain barrier) and the surrounding retina (ratio of leakage) was measured using digital imaging analysis in the late phases of the angiogram (9-10min). The AVP time was significantly prolonged ( P=0.001) in patients with open angle glaucoma (AVP 2.29+/-0.32 s) compared to healthy subjects (AVP 1.37+/-0.42 s). The mean percentage of the optic nerve head nonperfusion was 16%. The ratio of optic nerve head fluorescence compared to retinal reference loci was significantly increased (P = 0.02) in patients with glaucoma (1.32+/-0.25) compared with normal subjects (1.32+/-0.19). Fluorescein angiography revealed altered retinal perfusion along with optic nerve head nonperfusion and increased vascular leakage in open angle glaucoma patients. These factors appear to influence each other, with ultrastructural changes of the lamina cribrosa accompanying changes in the vasculature and nerve fibers. Longitudinal and interventive studies should help better elucidate the relationship between circulatory and neural loss, adding vasoprotective therapeutic approaches to interfere with the glaucomatous neurodegenerative chain of events.
    Brain Research Bulletin 03/2004; 62(6):517-24. · 2.94 Impact Factor
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    ABSTRACT: To evaluate absolute filling defects of the optic nerve head in normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG) and to compare the filling defects with topographic analysis of the optic disc. Twenty-five patients with NTG, 25 patients with POAG, and 25 age-matched controls were included. Fluorescein angiograms were performed by means of a scanning laser ophthalmoscope. The extent of absolute filling defects of the optic nerve head was assessed using digital image analysis of early-phase angiograms. Topographic measurements of the optic disc were acquired using the Heidelberg Retina Tomograph II. Absolute filling defects were significantly larger (P =.001) and were seen more often (P<.001) in patients with NTG (n = 18) and POAG (n = 19) compared with controls (n = 3). Rim area (P =.006), rim volume (P =.007), cup-disc area ratio (P =.008), linear cup-disc ratio (P =.005), maximum cup depth (P =.002), cup shape measure (P =.03), and nerve fiber layer thickness (P =.008) and cross-sectional area (P =.006) were significantly different between patients with glaucoma and controls. Absolute filling defects were significantly correlated with cup area (r = 0.31; P =.007), rim area (r = -0.38; P<.001), rim volume (r = -0.35; P =.002), cup-disc area ratio (r = 0.49; P<.001), linear cup-disc ratio (r = 0.48; P<.001), cup shape measure (r = 0.27; P =.02), and nerve fiber layer thickness (r = -0.33; P =.004) and cross-sectional area (r = -0.30; P =.009). Fluorescein filling defects of the optic disc are present in NTG and POAG. The extent of these filling defects is correlated with the morphologic disc damage.
    Archives of Ophthalmology 03/2004; 122(2):195-201. · 3.83 Impact Factor
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    ABSTRACT: A prospective, randomised study to evaluate effects of brinzolamide on ocular haemodynamics in healthy volunteers. 30 volunteers (12 men, 18 women; 28.3 (SD 7.8) years) were prospectively randomised to either brinzolamide or placebo during a 2 week double masked treatment trial. Examinations were performed at baseline and after 2 weeks of treatment. Intraocular pressure was measured and automatic static perimetry (Humphrey field analyser, 24-2) and contrast sensitivity (CSV 1000, Vector Vision) were performed. Retrobulbar blood flow velocities (peak systolic and end diastolic velocity) and resistive indices (RI) of ophthalmic artery, central retinal artery and of temporal and nasal short posterior ciliary arteries were measured by colour Doppler imaging (Sonoline Sienna Siemens). In video fluorescein angiograms (scanning laser ophthalmoscope, Rodenstock) arteriovenous passage time (AVP, dilution curves) and peripapillary diameters of retinal arterioles and venules were measured by means of digital image analysis. Intraocular pressure was significantly decreased by brinzolamide (p<0.0001). Neither brinzolamide nor placebo changed visual field global indices after treatment. Contrast sensitivity at 3 cycles per degree was significantly higher in the placebo group (p<0.05). Apart from an increase of RI in ophthalmic artery under placebo treatment (p<0.05) there was no effect in retrobulbar haemodynamics in both groups. Brinzolamide therapy alone resulted in a significant reduction of AVP compared to baseline (p<0.05), while peripapillary retinal vessels diameters remained unaffected. Apart from the expected decrease of intraocular pressure brinzolamide showed no significant change in retrobulbar haemodynamics, but a significant shortening of AVP. Since in glaucoma AVP is prolonged indicating vascular dysfunction this effect might be beneficial in glaucoma therapy.
    British Journal of Ophthalmology 02/2004; 88(2):257-62. · 2.73 Impact Factor
  • Klinische Monatsblatter Fur Augenheilkunde - KLIN MONATSBL AUGENHEILK. 01/2004; 221(10):867-871.
  • A. Remky, N. Plange, J. Klok, O. Arend
    Spektrum Der Augenheilkunde - SPEKTRUM AUGENHEILKD. 01/2004; 18(1):25-30.
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    ABSTRACT: The purpose of this prospective, randomized, cross-over study was to investigate and compare the microcirculatory effects of timolol, dorzolamide and latanoprost in newly diagnosed primary open-angle glaucoma (POAG) patients. Haemodynamics were assessed using fluorescein angiography by means of a scanning laser ophthalmoscope (SLO). Visual function and visual field indices were evaluated during all drug treatment phases. Fourteen patients with newly diagnosed POAG (age 55 +/- 7 years; 10 male, four female) were recruited for the study. At baseline examination, blood pressure, heart rate, intraocular pressure (IOP), SLO angiograms, and contrast sensitivity (CS) were analysed. Patients then randomly received timolol, dorzolamide or latanoprost treatment for 4 weeks. Patients then returned and all procedures were repeated and assessed. Arteriovenous passage times (AVPs), peripapillary arterial and venous diameters were assessed from SLO angiograms, using digital image processing. Calculated ocular perfusion pressure was determined for each treatment phase. Intraocular pressure was significantly lowered by each drug compared to baseline (p < 0.0001). Arteriovenous passage times were significantly shortened after dorzolamide application compared to baseline (p = 0.009), whereas neither timolol nor latanoprost treatment resulted in significant AVP changes. Peripapillary arterial and venous diameters, systolic and diastolic blood pressure, heart rate and ocular perfusion pressures were not significantly altered during any treatment phase. Contrast sensitivity testing at 6 cycles/degree (c.p.d.) revealed a significant rise after dorzolamide compared to timolol (p = 0.007). Our results suggest that dorzolamide treatment significantly shortened AVP times in newly diagnosed open-angle glaucoma patients, whereas timolol and latanoprost had no significant effect. Given that prolonged AVP times have been associated with disease progression in glaucoma; dorzolamide treatment may benefit optic nervehead preservation by increasing ocular perfusion.
    Acta Ophthalmologica Scandinavica 10/2003; 81(5):474-9. · 1.85 Impact Factor
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    ABSTRACT: The 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. In 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. Variance 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. SWS 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.
    Albrecht von Graæes Archiv für Ophthalmologie 07/2003; 241(6):468-71. · 1.93 Impact Factor
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    Acta Ophthalmologica Scandinavica 06/2003; 76(1):43 - 49. · 1.85 Impact Factor
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    N Plange, A Remky, O Arend
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    ABSTRACT: 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. 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. 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 (PSV(CRA): r = -0.41; EDV(CRA): r = -0.34), with the PSV and EDV of the NPCA (PSV(NPCA): r = -0.34; EDV(NPCA): 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 (RI(NPCA): r = 0.28; RI(TPCA): r = 0.29). 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.
    British Journal of Ophthalmology 06/2003; 87(6):731-6. · 2.73 Impact Factor
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    ABSTRACT: To review the role of ocular perfusion in the pathophysiology of diabetic retinopathy, one of the leading causes of irreversible blindness in the industrialized world. We carried out a Medline search of the literature published in English or with English abstracts from 1966 to 2000 using various combinations of relevant key words. Hyperglycaemia leads to a wide variety of vascular abnormalities at the microvascular and macrovascular levels, including abnormal autoregulation. Three major aspects of ocular perfusion in diabetic retinopathy require additional investigation. Firstly, the precise mechanisms that link elevated glucose to dysfunction of retinal vascular cells need to be identified. Secondly, those factors that lead to both capillary dropout and to angiogenesis, twin processes that are linked to tissue hypoxia and lead to excess perfusion, increased risk of extravascular leakage and frank haemorrhage, must be carefully delineated. Finally, once specific knowledge of disease fundamentals has been amassed, tests of therapies to reverse or prevent these pathological processes can move forward.
    Acta Ophthalmologica Scandinavica 11/2002; 80(5):468-77. · 1.85 Impact Factor

Publication Stats

2k Citations
191.13 Total Impact Points

Institutions

  • 1990–2009
    • University Hospital RWTH Aachen
      Aachen, North Rhine-Westphalia, Germany
  • 2006
    • Augenzentrum Annapark
      Alsdorf, Rheinland-Pfalz, Germany
  • 1991–2006
    • RWTH Aachen University
      • Department of Ophthalmology
      Aachen, North Rhine-Westphalia, Germany
  • 1994–2000
    • Indiana University-Purdue University Indianapolis
      • Department of Ophthalmology
      Indianapolis, IN, United States
  • 1997
    • Indiana University Bloomington
      • School of Medicine
      Bloomington, IN, United States
  • 1993–1995
    • Harvard Medical School
      Boston, Massachusetts, United States