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Biomedical subjects

O Arend

Publications and source records attributed to O Arend.

At least 19 recordsLinked to original sources

[HES 130 as a continuous supplement for organ culture of human corneas?].

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Cornea↗

24-h blood pressure monitoring in normal tension glaucoma: night-time blood pressure variability.

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.

Aged↗

[Colour Doppler imaging in normal pressure glaucoma patients].

AIM: 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. METHOD: 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. RESULTS: 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. CONCLUSION: 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.

Adult↗

[Defect closure with scleral grafts].

BACKGROUND: 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. METHOD: 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). RESULTS: 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. CONCLUSION: 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.

Eye Injuries, Penetrating↗

Comparison of colour Doppler imaging and retinal scanning laser fluorescein angiography in healthy volunteers and normal pressure glaucoma patients.

PURPOSE: To correlate retinal circulatory measurements using scanning laser fluorescein angiography and flow velocities of retrobulbar vessels measured by means of colour Doppler imaging. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Adult↗

Effects of brinzolamide on ocular haemodynamics in healthy volunteers.

AIM: A prospective, randomised study to evaluate effects of brinzolamide on ocular haemodynamics in healthy volunteers. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Adult↗

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 (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). 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.

Blood Flow Velocity↗

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.

Blood Flow Velocity↗

[Absolute filling defects of the optic disc in fluorescein angiograms in glaucoma--a retrospective clinical study].

BACKGROUND: Analysis of clinical importance of the size of filling defects in fluorescein angiograms in primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG), ocular hypertension and subjects with physiological excavations in comparison to visual field loss, optic nerve head morphology and hemodynamics. PATIENTS AND METHODS: 75 patients (POAG, NTG, ocular hypertension) and 10 healthy subjects with physiological excavations were included in this study. In digitized video fluorescein angiograms (Scanning Laser Ophthalmoscope) the size of absolute filling defects of the optic disc was quantified in the early venous phase and expressed by percentage of the optic disc. Visual fields were obtained by conventional static perimetry (Humphrey 24-2) and graded in stages of glaucoma visual field defects (Aulhorn I-V). Optic disc excavations were evaluated as cup-to-disc-area-ratios. RESULTS: The filling defects correlated with the visual-field loss stages of Aulhorn and the visual field indices MD (mean deviation), PSD (pattern standard deviation) and CPSD (corrected pattern standard deviation). There was no correlation with the index SF (short-term fluctuation) and with systemic hemodynamics (blood pressure, perfusion pressure) or the IOP. Absolute filling defects correlated with the cup-to-disc-area-ratio in NTG. The absolute filling defects were larger in patients with glaucoma (POAG, NTG) in comparison to patients without glaucomatous visual field loss (ocular hypertension, glaucoma-like discs). No difference of filling defects was found in the glaucoma group (POAG, NTG). Patients with NTG had larger excavations and lower systolic blood pressures than patients with POAG. CONCLUSION: The size of fluorescein filling defects may be useful as a parameter for the evaluation of an ischemic lesion of the optic nerve head. Absolute filling defects may differentiate POAG from ocular hypertension and NTG from glaucoma-like discs without field defects. The results support the hypothesis that in POAG and NTG disturbances of the circulation result in similar filling defects of the optic disc and visual field loss.

Adult↗

Short wavelength automated perimetry in age related maculopathy.

BACKGROUND/AIMS: Previous studies reported the predictive value of the short wavelength sensitive (SWS) cone mediated sensitivity for visual outcome in age related macular degeneration. In this study SWS sensitivity was measured by commercially available blue on yellow perimetry in patients with non-exudative age related maculopathy (ARM) and compared with the presence of morphological risk factors and the status of the fellow eye. METHODS: In a prospective cross sectional study, 126 patients (57 males, 69 females, mean age 71 (SD 6) years) with ARM (visual acuity >20/50) were tested. Central visual fields (blue on yellow) were obtained with a conventional perimeter. Fundus slides were graded by two independent observers for soft drusen and presence of focal hyperpigmentation. RESULTS: Mean sensitivity and standard deviation of all patients exhibited a significant reduction with age. Patients with soft drusen had significantly lower sensitivity than those without, whereas there were no differences in visual acuity (log MAR). Sensitivity was also reduced in those eyes with fellow eyes having a sight threatening complication of age related macular degeneration (AMD). Eyes with focal hyperpigmentation compared with those without had no loss of sensitivity, but did have a significant decrease in the central part of the field compared with the more eccentric. CONCLUSION: SWS sensitivity loss is associated with common risk factors for progression to AMD. Short wavelength automated perimetry is moderately rapid and readily available. It may serve as a tool in future ARM trials.

Aged↗

[Intra-individual variability of blue-yellow perimetry].

BACKGROUND: Short wavelength automated perimetry (SWAP) is a sensitive method in detection of early glaucomatous damage. In this study, we compared intra-subject variability of global indices of SWAP and conventional white-on-white perimetry (WWP) in normal clinical conditions (without correction for lens yellowing). METHODS: SWAP and WWP (Humphrey field analyzer, 24-2 field, full threshold strategy) was performed in 68 eyes with glaucoma or glaucoma suspect and at the same day. The tests were repeated within 45 days (mean follow-up 16 +/- 13 days). RESULTS: At the follow-up test the mean defect was significantly reduced for both conditions, more pronounced for SWAP. Pattern standard deviation remained statistically equal for both conditions. The coefficient of correlation of baseline to follow-up was for SWAP PSD 0.88 with a slope of 1.05, for WWP PSD 0.7 with a slope of 0.83. The coefficient of variation for PSD was 17% for SWAP and 34% for WWP. CONCLUSIONS: The low intraindividual variability of SWAP enables early detection of glaucomatous field damage in the follow-up.

Adult↗

[Corneal transplantation and glaucoma].

BACKGROUND: Recent studies have shown that increased intraocular pressure following keratoplasty may cause progressive endothelial cell loss and thereby lead to early transplant failure. This study examined risk groups for development of postoperative glaucoma and thereby transplant failure. MATERIAL AND METHODS: Seventy-five patients with various diagnoses were followed up prospectively for 2, 4, 6, 12, 24, 36, 48, and 60 months. RESULTS: Of the 75 patients 22 showed elevated intraocular pressure after keratoplasty. One-third of these (n = 7) developed a chronic secondary glaucoma. The main risk factor was a preexisting glaucoma (P < 0.05, c2 test), followed by aphakia, especially if aphakia was present before keratoplasty. Three of the six patients with anterior synechia had increased intraocular pressure. Because of the small number of patients neither factors reached statistical significance. CONCLUSION: Intraocular pressure should be closely monitored especially in high-risk patients, although its measurement may not be exact by Schiötz and Goldmann tonometry. Digital impression and controls of the visual field should be carried out additionally.

Corneal Transplantation↗

A comparative study of betaxolol and dorzolamide effect on ocular circulation in normal-tension glaucoma patients.

OBJECTIVE: To determine whether dosages of a selective beta-blocking agent (betaxolol) and a topical carbonic anhydrase inhibitor (dorzolamide), sufficient to significantly lower intraocular pressure (IOP), have similar or disparate impact on the retinal and retrobulbar circulation. DESIGN: Counterbalanced crossover, with open-label use of medications. PARTICIPANTS: Nine persons with normal-tension glaucoma (NTG). INTERVENTION: After a 3-week drug washout, NTG patients were studied after 1 month of treatment with either dorzolamide or betaxolol, with determinations of IOP and retinal and retrobulbar hemodynamics. MAIN OUTCOME MEASURES: At baseline and after treatment with each drug, retinal arteriovenous passage time was determined by scanning laser ophthalmoscopy after fluorescein dye injection, and flow velocities in the central retinal and ophthalmic arteries were measured with color Doppler ultrasonography imaging. RESULTS: Betaxolol and dorzolamide each lowered IOP significantly, with these changes apparent and maximal after 2 weeks (each P < 0.05). In contrast, dorzolamide (but not betaxolol) accelerated arteriovenous passage of fluorescein dye in the inferior temporal quadrant of the retina (P < 0.05). Neither drug affected arteriovenous passage in the superotemporal retina or any aspect of central retinal or ophthalmic artery flow velocity after either 2 or 4 weeks. CONCLUSIONS: Although both dorzolamide and betaxolol are effective ocular hypotensive agents and their topical instillation leaves retrobulbar hemodynamics unaltered, dorzolamide alone accelerates inferotemporal retinal dye transit.

Adrenergic beta-Antagonists↗

[Clinical experiences with the "Swedish interactive threshold algorithm" (SITA)].

BACKGROUND: The "Swedish Interactive Threshold Algorithm" (SITA) is a new technique minimizing test time without reduction of data quality. In this retrospective study we compared visual fields assessed with the conventional full-threshold technique with those by SITA and analyzed qualitative and quantitative differences and the test time reduction of SITA. PATIENTS AND METHODS: 113 eyes with different glaucomatous field damage of 66 patients aged from 22 to 89 years were included. The patients underwent perimetry with each strategy within four months. Exclusion criteria were eyes with progressing glaucomatous damage and high rate of false-positive results or artifacts by corrective glasses. RESULTS: The qualitative differences of the analysis were small: full threshold demonstrated more relative scotomas in eyes with normal SITA readings, whereas scotomas assessed with SITA were often pronounced to absolute scotomas. Average time reduction by SITA was 40% and depended on the severity of glaucomatous stage. No reduction was found for advanced glaucoma, whereas normal fields using SITA were performed in half of the time of full threshold strategy. CONCLUSION: Differences of SITA to conventional full threshold testing may be related to fatigue effects of full threshold strategy due to longer test time. The reduction of test time enables more motivation for more frequent visual field examinations and thus a better detection of early glaucoma or progressing visual field damage.

Adult↗

Macular circulation in patients with diabetes mellitus with and without arterial hypertension.

BACKGROUND: Previous fluorescein angiographic studies have shown alterations in the macular microcirculation in patients with diabetes mellitus and arterial hypertension. In both diseases capillary blood velocity was reduced and capillary density decreased. These changes were more pronounced in diabetic patients. We have examined the influence of arterial hypertension in combination with diabetes mellitus. METHODS: 62 patients with diabetes mellitus and arterial hypertension (group 1) were matched with patients with diabetes mellitus but without arterial hypertension (group 2, match criteria: ETDRS stage of retinopathy). In all subjects fluorescein angiograms were performed with a scanning laser ophthalmoscope. Macular capillary blood velocity (CBV), perifoveal intercapillary area (PIA), the coefficient of variation of both parameters, the area of the foveal avascular zone (FAZ), and the arteriovenous passage time (AVP) were assessed by digital image analysis. RESULTS: Systolic and diastolic blood pressures were significantly increased in the patients with arterial hypertension (systolic p=0.0008; diastolic p=0.03). Neither dynamic measures (AVP: 1.64 (0.49) seconds (group 1), 1.72 (0.58) seconds (group 2); CBV: 1.98 (0.39) mm/s (group 1), 2.09 (0.43) mm/s (group 2)) nor morphological measures (PIA: 7985 (3137) microm(2) (group 1), 8338 (3376) microm(2) (group 2); FAZ: 0.319 (0.206) mm(2) (group 1), 0.363 (0.237) mm(2) (group 2)) were significantly different between the two groups of diabetic patients. CONCLUSION: Arterial hypertension did not result in more severe macular capillary dropout than diabetes without hypertension. This might be explained by the fact that most of the patients were being treated with antihypertensive drugs.

Adult↗