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Retinal Artery (retinal + artery)
Kinds of Retinal Artery Terms modified by Retinal Artery Selected AbstractsAbstract no.: 2 The influence of clozapine on tone of isolated bovine retinal arteriesFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2005Koen Boussery Aims:, It has been suggested that the atypical antipsychotic drug clozapine might be helpful in the development of new antiglaucoma agents, since it combines lowering of the intra-ocular pressure after topical instillation with vasodilation. However, the vasoactive influence of clozapine on ocular blood vessels has never been analysed. Therefore, this study aimed to evaluate whether clozapine has direct vasodilatory effects in isolated bovine retinal arteries (BRA) and to characterise pharmacologically the mechanisms involved. Methods:, Retinal arteries were isolated from bovine eyes and mounted in a wire-myograph for isometric tension recording. Concentration-response curves were generated by cumulative addition of clozapine (1 nM to 10 ,M) to the organ bath. Results:, Clozapine elicited a concentration-dependent relaxation of the BRA. Removal of the endothelium of the BRA, inhibition of nitric oxide synthase with N, -nitro-L-arginine and inhibition of soluble guanylyl cyclase with ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) significantly attenuated the clozapine-response, whereas cyclo-oxygenase inhibition with indomethacin had no influence. The Ca2+ channel activator Bay k8644, the nonselective 5-hydroxytryptamine receptor antagonist methiothepin and the adenosine receptor antagonist 8-(p-sulfophenyl) theophylline also failed in affecting the clozapine-induced relaxations. Conclusion:, Clozapine clearly relaxes bovine retinal arteries in a direct way. Endothelium-derived NO is involved in this response. However, prostanoids, calcium entry blockade, 5-HT7 receptor stimulation and adenosine receptor stimulation all seem to be not involved. [source] 2322: Reproducibility of retinal vessel hemoglobin oxygenation saturation in healthy subjectsACTA OPHTHALMOLOGICA, Issue 2010M LASTA Purpose Only recently systems for the measurement of hemoglobin oxygenation saturation in retinal vessels became commercially available. In the present study a fundus camera equipped with a dual wavelength transmission filter and a CCD camera was used (Imedos, Jena, Germany). Two monochromatic fundus images at 548 and 610 nm were recorded simultaneously and the oxygen saturation (SaO2) was calculated based on the optical density ratio. Methods A study on test/retest, short-term and day-to-day reproducibility of the technique was done in 14 healthy subjects. To assess test/retest variability fundus images were taken at each measurement cycle. To assess short-term reproducibility 2 such cycles of 3 fundus images were done within 15 minutes. Finally, this cycle of measurements was done on the next day to assess day-to-day reproducibility. Data were evaluated separately for retinal branch arteries and branch veins. The reproducibility was calculated using the standard deviation (SD) of the measurements. Results In retinal branch veins the SaO2 was 49±9% (range 32-69%, 38 vessels) and in retinal branch arteries 91±8% (range 77-112%, 40 vessels). The test/retest SD was 5.4±3.7% in retinal veins and 3.0±2.3% in retinal arteries. The short term SD was 4.7±3.7% in retinal veins and 2.9±2.1% in retinal arteries. The day-to-day SD was 6.2±4.1% in retinal veins and 4.0±2.8% in retinal arteries. Conclusion Our data indicate that the test/retest, short-term and day-to-day reproducibility of the technique is acceptable. Hence, the system may be adequate to follow oxygen saturation during disease processes. The data obtained in retinal branch arteries indicates, however, that the validity of measurements requires further studies. [source] Microstructural alterations of the retinal arterial blood column along the vessel axis in healthy volunteers with ageACTA OPHTHALMOLOGICA, Issue 2009IM LANZL Purpose We demonstrated previously that roughness of the retinal arterial blood column measured along the vessel axis increases in anamnestically healthy volunteers with increasing age. We termed it longitudinal retinal arterial profile (LAP). Whether LAP is altered with age in medically supervised healthy persons is investigated. Methods 82 medically healthy volunteers were examined by Dynamic Vessel Analyzer (IMEDOS, Jena, Germany) using stimulation with flickering light. 3 age groups were formed: young (N=27, 30,5±4,3 years), middle age (N=28, 42,3±3,3 years) and seniors (N=27, 64,0±5,0 years). Included in the analysis were volunteers without medical vascular risk factors defined as: blood pressure < 140/90 mmHg, HDL > 35 mg/dl, LDL < 190 mg/dl and glucose levels < 110 mg/dl. Retinal arterial diameters were measured along 1 mm vessel segments to obtain LAP. Differences were analyzed using Fourier transformation. Results In all age groups LAP do not change during all stages of the arterial response. Arterial diameters in the senior group were reduced in comparison to the young group at all stages of the vessel reaction (p<0,05). There are differences in LAP between the age groups. Compared to young persons, seniors showed significantly diminished waves with a period of 417 µm at all stages of the arterial reaction, whereas young volunteers showed less pronounced waves with a period of 208 µm (p<0,05). Conclusion Our results represent the healthy aging process in retinal vasculature. Age related microstructural changes in longitudinal profiles of retinal arteries in medically healthy persons might be an indication for alterations in the vascular endothelium and smooth musculature. [source] The therapeutic effects of retinal laser treatment and vitrectomy.ACTA OPHTHALMOLOGICA, Issue 5 2001A theory based on oxygen, vascular physiology ABSTRACT. The physiologic mechanism of photocoagulation can been seen in the following steps. The physical light energy is absorbed in the melanin of the retinal pigment epithelium. The adjacent photoreceptors are destroyed and are replaced by a glial scar and the oxygen consumption of the outer retina is reduced. Oxygen that normally diffuses from the choriocapillaris into the retina can now diffuse through the laser scars in the photoreceptor layer without being consumed in the mitochondria of the photoreceptors. This oxygen flux reaches the inner retina to relieve inner retinal hypoxia and raise the oxygen tension. As a result, the retinal arteries constrict and the bloodflow decreases. Hypoxia relief reduces production of growth factors such as VEGF and neovascularization is reduced or stopped. Vasoconstriction increases arteriolar resistance, decreases hydrostatic pressure in capillaries and venules and reduces edema formation according to Starling's law. Vitrectomy also improves retinal oxygenation by allowing oxygen and other nutrients to be transported in water currents in the vitreous cavity from well oxygenated to ischemic areas of the retina. Vitrectomy and retinal photocoagulation both improve retinal oxygenation and both reduce diabetic macular edema and retinal neovascularization. [source] Comparison of orbital colour Doppler findings with computed tomography angiographyCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2000Bill Gillies ABSTRACT Colour Doppler imaging (CDI) of orbital vessels is non- invasive but may be fallacious, while computed tomography (CT) angiography displays a visual outline of orbital vessels. We compared clinical findings of the two methods in 33 patients with a wide variety of clinical conditions. It was not possible to visualize the central retinal arteries with CT angiography, but it was possible to show the intracranial carotid, which CDI could not. Changes in the ophthalmic arteries on CDI usually showed changes in calibre on CT angiography. Patients with unexplained or gross visual loss often showed marked abnormalities on CT scanning, not entirely consistent with the clinical picture. Several patients showed marked ectasia of the intracranial carotid along with variable clinical findings. Findings on CT angiography complement and augment those on CDI, and are likely to be more clinically valuable in the future. [source] Effects of intravitreal bevacizumab (Avastin®) therapy on retrobulbar blood flow parameters in patients with neovascular age-related macular degenerationJOURNAL OF CLINICAL ULTRASOUND, Issue 2 2010Ahmet Mete MD Abstract Background. To investigate the effects of intravitreal bevacizumab on retrobulbar circulation in patients with neovascular age-related macular degeneration (AMD). Method. Thirty patients with neovascular age-related macular degeneration were assessed prospectively by both color Doppler imaging and fundus fluorescein angiography. Spectral Doppler analysis allowed the measurement of the maximum velocity (Vmax) and minimum velocity (Vmin) of the central retinal vein (CRV), and peak systolic (PSV), end-diastolic (EDV) velocities of blood flows, and pulsatility index (PI) and resistance index (RI) values in the central retinal artery (CRA), nasal and temporal posterior ciliary arteries (NPCA, TPCA), and ophthalmic artery (OA). The t test for paired samples was used to compare retrobulbar blood flow values before and after intravitreal bevacizumab injection. Result. PSV and EDV of the NPCA and PSV of the TPCA were significantly decreased after intravitreal bevacizumab injection (p < 0.05). There was no statistically significant difference in the other parameters. Conclusion. Our results suggest that intravitreal bevacizumab therapy has a measurable effect on retrobulbar blood flow. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound 2010 [source] Orbital blood flow velocities in patients with rheumatoid arthritisJOURNAL OF CLINICAL ULTRASOUND, Issue 7 2007Besir Erdogmus MD Abstract Purpose. To assess orbital blood flow changes in patients with rheumatoid arthritis using Doppler sonography. Patients and Methods. The study comprised 35 patients who were diagnosed with RA and were treated at the Department of Physical Therapy and Rehabilitation at Duzce Medical School. A control group consisted of 35 healthy volunteers. Color Doppler imaging was used to measure peak systolic velocity (PSV) and end diastolic velocity (EDV), from which the resistance index (RI) was calculated in the ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary arteries (PCAs). Results. In the OA, PSV, EDV, and RI were, respectively, 36.7 ± 0.6 cm/sec, 9.7 ± 0.2 cm/sec, and 0.73 in the control group versus 34.7 ± 3.0 cm/sec, 9.1 ± 1.1 cm/sec, and 0.74 in the patient group. In the CRA, they were, respectively, 11.8 ± 1.7 cm/sec, 3.6 ± 0.7 cm/sec, and 0.66 in the control group versus 11.1 ± 1.7 cm/sec, 3.4 ± 0.7 cm/sec, and 0.68 in the patient group. In the PCAs, they were, respectively, 13.2 ± 1.2 cm/sec, 4.7 ± 0.6 cm/sec, and 0.65 in the control group versus 12.4 ± 1.2 cm/sec, 4.2 ± 0.6 cm/sec, and 0.66 in the PCAs. PSV, EDV, and RI of the PCAs and OA and RI of the CRA were significantly different between patients and controls, whereas there was no difference in the serum levels of glucose, triglyceride, low-density lipoprotein cholesterol, and total cholesterol. In the patient group, there was a significant correlation between orbital blood flow and duration of disease. Conclusion. Ocular blood flow appears to be slightly lower in RA patients than in healthy controls, suggesting that RA is a systemic inflammatory disease that may also involve ocular vessels. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007 [source] Doppler measurement of blood flow velocities in extraocular orbital vessels in patients with obstructive sleep apnea syndromeJOURNAL OF CLINICAL ULTRASOUND, Issue 5 2003C. Zuhal Erdem MD Abstract Purpose. We used color Doppler sonography to determine blood flow velocities in the extraocular orbital vessels of patients with obstructive sleep apnea syndrome (OSAS) and compared the results with those of healthy control subjects without OSAS. Methods. Patients with OSAS were classified according to the apnea-hypopnea index (AHI) as having mild OSAS (AHI < 20) or severe OSAS (AHI , 20). The peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistance index were measured in the ophthalmic artery (OA), central retinal artery (CRA), lateral short posterior ciliary artery, and medial short posterior ciliary artery using color Doppler sonography. Only 1 eye was measured in each study participant, and right and left eyes were chosen randomly. The blood flow velocities of patients with OSAS and those of control subjects were compared with the Kruskal-Wallis test and Wilcoxon's rank-sum test. Results. The study comprised 30 patients (15 with mild and 15 with severe OSAS) and 20 healthy control subjects. Blood flow velocities were higher in most measured vessels in patients with OSAS than they were in the control subjects. Among patients with mild OSAS, the PSVs and EDVs in the posterior ciliary arteries were statistically significantly higher than those of the control group (p < 0.05), but those in the OA and CRA did not differ significantly between the mild OSAS group and the control group (p > 0.05). However, as the severity of OSAS increased, the PSVs and EDVs of the OA and CRA were also affected (p < 0.05). Conclusions. Color Doppler sonographic measurements of blood flow parameters in the orbital vessels may differ significantly between patients with OSAS and those without the syndrome. Therefore, OSAS should be considered in addition to other conditions when interpreting the results of color Doppler sonography of the extraocular orbital vessels if the clinical history points toward such a diagnosis. © 2003 Wiley Periodicals, Inc. 31:250,257, 2003 [source] Observer experience improves reproducibility of color doppler sonography of orbital blood vesselsJOURNAL OF CLINICAL ULTRASOUND, Issue 6 2002János Németh MD Abstract Purpose. The study investigated the reproducibility of orbital blood flow measurements with color Doppler imaging (CDI) at different stages of observer experience. Methods. The subjects were 31 healthy volunteers and 2 sequential groups of 25 glaucoma patients each. Repeated blood flow measurements (usually 3 sets) in orbital vessels (ophthalmic artery, short posterior ciliary arteries, central retinal artery, and central retinal vein) were performed by the same observer in a single session in each subject. Results. The parameters with the best reproducibility were the resistance index (mean coefficient of variation [COV], 3.3,8.8%), the peak systolic velocity (mean COV, 6.9,13.7%), the time-averaged velocity (mean COV, 7.2,16.0%), and the systolic acceleration time (mean COV, 8.8,12.3%). The mean COV was greater (9.9,20.3%) for the other arterial flow parameters (end-diastolic velocity and systolic acceleration) and for the venous flow velocities (maximum and minimum). The COVs of the parameters were improved by 20,40% as the observer became more experienced in ophthalmic CDI. Conclusions. We confirm the general reliability of CDI measurements in orbital vessels and show that observer experience improves reproducibility. It appears, however, that observer performance in these measurements is vessel specific. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30:332,335, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10079 [source] The morphometric analysis of the central retinal arteryOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 4 2005Necdet Kocabiyik Abstract In this study, we aimed to investigate some features of the central retinal artery (CRA), which supplies the internal aspect of the retina. The CRA is the main vessel supplying blood to the retina. The origin, course and penetration point of the optic nerve by the CRA were studied in 30 human orbits. We compared the right sides to the left sides on the basis of gender in order to statistically analyse the relation between them. The CRA arose directly from the ophthalmic artery in 28 specimens. In two specimens, however, it arose in common with the medial posterior ciliary artery. When we observed the penetration point (site) of the CRA into the optic nerve, in 28 of 30 (93.3%) cases, the artery entered the nerve from the lower medial aspect and in two (6.7%) cases from the upper lateral aspect. The CRA penetrated the optic nerve between 6.4 and 15.2 mm behind the eyeball and reached the eyeball through the centre of the optic nerve. Because of the small diameter of the artery, it has a high risk of getting damaged during a surgical approach to the orbit. Therefore the anatomical relationships of this artery must be well known. [source] Access of autonomic nerves through the optic canal, and their orbital distribution in manTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2003Gordon L. Ruskell Abstract The notion that autonomic nerves from the internal carotid plexus are transmitted to the orbit with the ophthalmic artery through the optic canal has been variously assumed, disregarded, or denied, but never demonstrated. The objective of this study was to examine the contents of the canal, identify any autonomic nerves, and follow their passage within the orbit. The soft tissues of the optic canal, and the apical tissues of the orbit were removed and examined histologically using 10 cadaver preparations. Additionally, tissues from an orbital exenteration and 10 ocular enucleation or donor specimens were prepared. Some of the latter material was examined with an electron microscope. Numerous autonomic nerves (four to 25, ranging in diameter from 23 to 130 ,m) entered the orbit from the internal carotid plexus in the periosteum of the optic canal, the optic nerve dura mater, or the adventitia of the ophthalmic artery. In the orbit they advanced in the loose connective tissue covering the optic nerve dura and joined ciliary nerves close to the eye or entered the eye directly. None were observed to penetrate the dura, apart from a nerve accompanying the central retinal artery. Others were distributed with the ophthalmic artery and its branches. It is concluded that the optic canal is a regular, and often major, route for autonomic nerve distribution to the eye and orbit. Anat Rec Part A 275A:973,978, 2003. © 2003 Wiley-Liss, Inc. [source] 3254: Neurovascular coupling in the retrobulbar ciliary circulationACTA OPHTHALMOLOGICA, Issue 2010O ZEITZ Purpose Perfusion of the retina is adapted to the metabolic demand by neurovascular coupling. Neurovascular coupling has shown to be present in the retinal vasculature, but not in vessels supplying the optic nerve. The present study investigated the presence of neurovascular coupling in the anterior part of the optic nerve in healthy and glaucoma subjects. Methods Retrobulbar blood flow velocities were determined by color Doppler imaging (CDI). A Siemens Elegra ultrasound system with a 7.5L40 transducer was used. Peak-systolic and end-diastolic velocities (PSV and EDV) in the central retinal artery (CRA) or the short posterior ciliary artery (SPCA) were the primary readout. CDI measurements were performed shortly before, during, immediately after, 60 s after, and 120 s after a 10-Hz flicker stimulation of the retina. Results Thirty-five glaucoma patients and 44 healthy control subjects were included in the study. In the SPCA of healthy controls, flicker stimulation led to a rise of PSV from 9.7±0.8 to 12.5±0.8 cm/s (P<0.001; N=24) and of EDV from 2.4±0.3 to 3.6±0.3 cm/s (P<0.001; N=24). This effect was not detectable in glaucoma patients. In the CRA, flicker light led to an increase of EDV from 2.1±0.2 to 3.0±0.3 cm/s (P=0.002; N=20) in healthy volunteers and from 1.3±0.2 to 2.0±0.2 cm/s in glaucoma patients (P=0.004; N=15). PSV was affected by flicker stimulation in neither the healthy volunteers nor glaucoma patients. Conclusion The data indicate the presence of neurovascular coupling in the vascular bed supplied by the paraoptic SPCA. The response pattern to the flicker stimulus differs between healthy and glaucoma subjects. [source] Effect of acute postural variation on diabetic macular oedemaACTA OPHTHALMOLOGICA, Issue 2 2010Martin Vinten Abstract. Purpose:, This study aimed to study the pathophysiology of diabetic macular oedema (DMO) by analysis of concomitant changes in macular volume (MV), mean arterial blood pressure (MABP), intraocular pressure (IOP), and retinal artery and vein diameters in response to acute postural changes in patients with DMO and healthy subjects. Methods:, Thirteen patients with DMO (13 eyes) and five healthy subjects (five eyes) were examined after resting in a chair for 15 mins using optical coherence tomography to measure MV and fundus photography to assess retinal vessel diameters. The patients then lay down for 60 mins, during which they were examined repeatedly before they were reseated and examined again. Intraocular pressure was measured using pulse-air tonometry, arterial blood pressure by sphygomanometry and fluid columns using rulers and a spirit level. Results:, In healthy subjects, retinal artery (p = 0.02) and vein (p = 0.001) diameters decreased when subjects lay down, whereas MV remained stable. In patients with DMO, no orthostatic variation in retinal vessel diameters could be demonstrated, whereas MV had increased by 2.4 ± 0.6% (mean ± standard error of the mean; p = 0.006) 50 mins after assuming a recumbent position. In both healthy subjects and DMO patients, MABP decreased and IOP increased in a recumbent position, with no significant difference between the groups. Conclusions: The increase in MV that occurs in DMO when changing from a seated to a recumbent position is associated with a failure of retinal artery contraction, a response seen in healthy subjects that appears to counter-regulate the increase in ocular perfusion pressure caused by assuming a recumbent position. [source] Twelve-hour reproducibility of retinal and optic nerve blood flow parameters in healthy individualsACTA OPHTHALMOLOGICA, Issue 8 2009Alexandra Luksch Abstract. Purpose:, The aim of the present study was to investigate the reproducibility and potential diurnal variation of optic nerve head and retinal blood flow parameters in healthy individuals over a period of 12 hr. Methods:, We measured optic nerve head and retinal blood flow parameters in 16 healthy male non-smoking individuals at five time-points during the day (08:00, 11:00, 14:00, 17:00 and 20:00 hr). Outcome parameters were perimacular white blood cell flux (as assessed with the blue field entoptic technique), blood velocities in retinal veins (as assessed with bi-directional laser Doppler velocimetry), retinal arterial and venous diameters (as assessed with the retinal vessel analyser), optic nerve head blood flow, volume and velocity (as assessed with single point and scanning laser Doppler flowmetry) and blood velocities in the central retinal artery (as assessed with colour Doppler imaging). The coefficient of variation and the maximum change from baseline in an individual were calculated for each outcome parameter. Results:, No diurnal variation in optic nerve head or retinal blood flow was observed with any of the techniques employed. Coefficients of variation were between 1.6% and 18.5% for all outcome parameters. The maximum change from baseline in an individual was much higher, ranging from 3.7% to 78.2%. Conclusion:, Our data indicate that in healthy individuals the selected techniques provide adequate reproducibility to be used in clinical studies. However, in patients with eye diseases and reduced vision the reproducibility may be considerably worse. [source] Colour Doppler examination of early and late orbital haemodynamic changes in eyes with eyelid oedema due to blunt traumaACTA OPHTHALMOLOGICA, Issue 2 2006Mehmet Numan Alp Abstract. Purpose:,To evaluate the early and late alterations in orbital blood flow parameters in eyes with severe eyelid swelling due to blunt trauma by using colour Doppler ultrasonography (CDU). Methods:,Blood flow parameters in the ophthalmic artery (OA), central retinal artery (CRA), short posterior ciliary arteries (SPCAs) and central retinal vein (CRV) were examined by CDU in 62 eyes of 31 patients with unilateral blunt trauma and in 32 eyes of 32 normal subjects. Patients were examined within the first 5 days and at least 1 month after trauma. The traumatized eyes of patients were designated ,trauma eyes', non-traumatized fellow eyes were designated ,fellow eyes', and randomly chosen eyes of control subjects ,control eyes'. Results:,In the early phase, peak systolic velocity (PSV) and end diastolic velocity (EDV) in the OA in trauma eyes were statistically significantly higher than in both fellow eyes and control eyes: the p-values for the differences in PSV and EDV between trauma eyes and fellow eyes were p < 0.001 and p = 0.001, respectively, while the p-values for the differences in PSV and EDV between trauma eyes and control eyes were p = 0.002 and p = 0.019, respectively). No other blood flow parameters obtained at the first examination in all groups were statistically different. In the late phase, PSV in the OA in trauma eyes was found to be higher than that in both fellow eyes and control eyes, but the difference was significant only between trauma eyes and fellow eyes (p = 0.028). End diastolic velocity in the CRA was statistically significantly lower in fellow eyes than in control eyes (p = 0.046). No other blood flow parameters in any vessels examined in fellow eyes and control eyes were statistically significantly different during the study period. Conclusion:,Blood flow velocities detected by CDU are increased in the OA in eyes with eyelid oedema due to blunt trauma and some of these changes may persist for up to 1 month. This effect seems to be a consequence of trauma-induced hyperaemia in the orbital soft tissues rather than an expression of traumatic choroidal vasculopathy. [source] The effect of photodynamic therapy on retrobulbar blood flow parametersCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 1 2008Peykan Türkçüo, lu MD Abstract Purpose:, To investigate the effect of photodynamic therapy (PDT) on retrobulbar blood flow parameters. Methods:, Twenty-four patients with choroidal neovascular membrane of at least four MPS disc area in one eye due to age-related macular degeneration scheduled for PDT were recruited. Peak systolic and end diastolic velocity of ophthalmic, central retinal and posterior ciliary artery of both eyes were measured with colour Doppler imaging and resistivity index were computed before, at the first and fourth weeks following PDT. Results:, Following PDT, the mean peak systolic velocity of posterior ciliary artery increased significantly to a value of 31.90 ± 13.44 at the first (P = 0001), then returned to an insignificant value of 29.95 ± 13.03 at the fourth week (P = 0.360), when compared with pre-PDT mean measurement (30.16 ± 13.15). Resistivity index of posterior ciliary artery also increased significantly to a value of 0.740 ± 0.77 at the first (P = 0.046), then returned to an insignificant value of 0.666 ± 0.14 at the fourth week (P = 0.407), when compared with pre-PDT mean measurement (0.709 ± 0.90). All the other measured data (peak systolic velocity, end diastolic velocity, resistivity index of ophthalmic and central retinal artery; end diastolic velocity of posterior ciliary artery of the treated eyes; all colour Doppler imaging measurements of untreated eyes) did not show any significant change at the first and fourth week following PDT, when compared with the pre-PDT values. Conclusion:, The peak systolic velocity and resistivity index of the posterior ciliary artery appear to increase in the first week and return to their baseline values at the fourth week following PDT. [source] Optic nerve blood flow in glaucomaCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 3 2000Renuka Bathija FRACO FRACS Background: Glaucomatous optic neuropathy often occurs in the absence of elevated intraocular pressure and, conversely, elevated intraocular pressure may occur without associated damage of the optic nerve. These findings challenge the simple explanation of intraocular pressure being the sole cause of neural loss and have led to theories of ischaemic causes of the morbidity. This paper reviews the vascular anatomy of the optic disc, the factors that control its blood flow and the existing techniques for measurement of the blood flow. It also briefly discusses the possible role of apoptosis in glaucomatous visual loss. Method: Literature review. Conclusions: The posterior ciliary artery circulation is the main source of the blood supply to the optic nerve head with additional lesser supply via the central retinal artery and the choroidal circulation. There is considerable individual variation in the distribution of this circulation and complex regulatory systems govern its function. It is likely that microcirculatory changes in the vascular supply of the optic disc play a role in glaucoma, either as the primary abnormality or as a co-factor that increases susceptibility to damage from increased intraocular pressure through impaired auto-regulation. Clinical trials are currently in progress for the treatment of glaucoma with systemically administered agents that are antagonists of the receptors that mediate glutamine toxicity, a factor in the process of apoptosis. [source] | ||||||||||