Biomedical subjects

K Gugleta

Publications and source records attributed to K Gugleta.

14 recordsLinked to original sources

PubMed2004

Ocular blood flow alteration in glaucoma is related to systemic vascular dysregulation.

AIMS: To investigate the source of ocular blood flow alterations in glaucoma. METHODS: In 56 patients with open angle glaucoma, blood flow parameters were obtained from both eyes in the ophthalmic and central retinal artery by means of colour Doppler imaging, as well as in the choroidal circulation and the neuroretinal rim of the optic nerve by means of laser Doppler flowmetry. Based on these haemodynamic parameters, a cluster analysis (two groups) was performed and differences with regard to risk factors were assessed between clusters. RESULTS: Ocular blood flow data in the two clusters indicated that the two groups (cluster 1 = 26 patient with higher blood flow values; cluster 2 = 30 patients with lower blood flow values) differed mainly in choroidal and optic nerve blood flow. No differences in sex distribution, propensity to have normal tension glaucoma, age, endothelin-1 plasma levels, visual field damage, intraocular pressure, or systemic blood pressure parameters were observed between the two clusters. However, 12 patients (46%) from the cluster with high ocular blood flow values showed a vasospastic response in nailfold capillaroscopy, while such a response was observed in 24 patients (80%) of the cluster with low ocular blood flow values. This difference in vasospastic propensity was statistically significant (p = 0.0121). CONCLUSIONS: Ocular blood flow alterations in glaucoma patients seem, at least partly, to be related to a systemic vascular dysregulation.

Aged↗

PubMed2001

An evaluation of the effect of unoprostone isopropyl 0.15% on ocular hemodynamics in normal-tension glaucoma patients.

BACKGROUND: Because intraocular pressure-lowering agents should have a good safety profile with regard to ocular hemodynamics, the innocuousness of unoprostone isopropyl 0.15% with regard to ocular hemodynamics in vasospastic patients with normal-tension glaucoma was assessed in a pilot study. METHODS: Corneal temperature as a parameter of ocular blood flow and choroidal and optic nerve blood flow as assessed by means of laser Doppler flowmetry techniques were evaluated in 12 vasospastic normal-tension glaucoma patients in a prospective, randomized, observer-masked, two-period crossover, placebo-controlled pilot trial. RESULTS: Statistical analysis in 2 x 2 two-way analysis of variance models with two treatments (placebo and unoprostone isopropyl) and two assessments (baseline and after 1 week of treatment) as within-subject factors disclosed a lack of difference between eyes, between the treatment (placebo/unoprostone isopropyl) periods, and between baseline and after 1 week of treatment in corneal temperature, choroidal blood flow, and optic nerve blood flow. The differences between the results at baseline and after 1 week of treatment in these parameters were not significantly different between the placebo treatment period and the unoprostone isopropyl treatment period, and this was comparable in fellow eyes for all the parameters. CONCLUSION: Unoprostone isopropyl did not induce any alterations in ocular hemodynamics in this pilot study with vasospastic normal-tension glaucoma patients.

Antihypertensive Agents↗

PubMed2001

Retrobulbar blood flow in glaucoma patients with nocturnal over-dipping in systemic blood pressure.

PURPOSE: To evaluate the relationship between the circadian blood pressure rhythm and the retrobulbar blood flow in glaucoma patients. DESIGN: Cross-sectional study. METHODS: Circadian blood pressure measurements and color Doppler imaging (CDI) in the ophthalmic artery as well as the central retinal artery of one randomly selected eye were obtained in 193 primary open-angle glaucoma patients. CDI parameters were compared by means of analysis of covariance between patients with a nocturnal decrease in mean systemic blood pressure (MBP) below 20% of the average daytime MBP (over-dippers), patients with a decrease between 10% to 20% (dippers), and patients with a decrease of less than 10% (nondippers), using age, intraocular pressure (IOP), and MBP during color Doppler measurement as covariates. RESULTS: An analysis of covariance disclosed, after correcting for age, IOP, and MBP during color Doppler imaging, a significantly lower EDV (P =.0096) and a significantly higher RI (P =.033) in the central artery of over-dipping glaucoma patients compared with nondippers or dippers. This effect seemed independent of the use of vasoactive drugs . CONCLUSIONS: Glaucoma patients with a marked drop in nocturnal systemic blood pressure seem to have altered retrobulbar blood flow parameters, suggesting that an abnormal systemic blood pressure profile may be the manifestation of some kind of systemic vascular dysregulation relevant for the ocular circulation.

Adrenergic beta-Antagonists↗

PubMed2001

Effect of timolol on anterior optic nerve blood flow in patients with primary open-angle glaucoma as assessed by the Heidelberg retina flowmeter.

PURPOSE: To evaluate the effect of 0.5% timolol maleate on the capillary circulation of the anterior optic nerve head in patients with primary open-angle glaucoma and to compare the results with those obtained in a healthy control group. PATIENTS AND METHODS: Twelve patients with nonprogressive glaucoma and 12 age- and sex-matched healthy volunteers were included in this prospective study. Optic nerve head perfusion was examined by the Heidelberg Retina Flowmeter (HRF) in both groups. A 3-week washout period preceded the baseline measurement in the glaucoma group, and ONH blood flow was assessed again after 3 weeks of bilateral topical timolol treatment and 2 hours after timolol application. RESULTS: Intraocular pressure decreased significantly with timolol (P < 0.001). The HRF flow values for patients with glaucoma were comparable to those for a control group at baseline (P = 0.25), 3 weeks after timolol therapy (P = 0.09), and 2 hours after timolol instillation (P = 0.15). The glaucoma group showed no statistically significant change in the HRF parameter flow as compared with baseline, either after 3 weeks of timolol treatment or 2 hours after timolol instillation (P = 0.40). The heart rate and arterial systolic and diastolic blood pressure values showed no alteration after timolol therapy. CONCLUSIONS: Patients with nonprogressive glaucoma seem not to have an altered optic nerve blood flow as assessed by the HRF, and timolol treatment does not seem to alter the latter blood flow parameter in such patients.

Adrenergic beta-Antagonists↗

PubMed2000

Choroidal laser Doppler flowmetry in healthy subjects.

OBJECTIVE: To evaluate normal choroidal blood flow and its relationship with various factors such as age, systemic blood pressure, and intraocular pressure (IOP). METHODS: A total of 70 healthy subjects were recruited. Choroidal blood flow was assessed using a method based on laser Doppler flowmetry (LDF) technique. The LDF parameters of velocity, volume, and flux were obtained. The influence of age, mean systemic blood pressure, IOP, smoking, and sex on choroidal hemodynamic parameters was assessed in a multiple linear regression model. The correlations between interocular difference in IOP and interocular differences in the LDF parameters were assessed by means of the Pearson linear correlation factor. RESULTS: Velocity decreased significantly (P = .03) with advancing age of the subjects and volume increased significantly (P = .02) with increasing IOP. Mean blood pressure, smoking, and sex had no influence on the choroidal LDF parameters. Interocular difference in IOP correlated significantly with interocular difference in volume (R = 0.34, P<.005). CONCLUSION: Choroidal blood flow velocity decreased with increasing age of the subjects, while the volume of moving erythrocytes decreased with lower IOP.

Adolescent↗

PubMed2000

Relationship between ocular perfusion pressure and retrobulbar blood flow in patients with glaucoma with progressive damage.

PURPOSE: To evaluate the relationship between ocular perfusion pressure and color Doppler measurements in patients with glaucoma. MATERIALS AND METHODS: Twenty patients with primary open-angle glaucoma with visual field deterioration in spite of an intraocular pressure lowered below 21 mm Hg, 20 age-matched patients with glaucoma with stable visual fields, and 20 age-matched healthy controls were recruited. After a 20-minute rest in a supine position, intraocular pressure and color Doppler measurements parameters of the ophthalmic artery and the central retinal artery were obtained. Correlations between mean ocular perfusion pressure and color Doppler measurements parameters were determined. RESULTS: Patients with glaucoma showed a higher intraocular pressure (P <.0008) and a lower mean ocular perfusion pressure (P <.0045) compared with healthy subjects. Patients with deteriorating glaucoma showed a lower mean blood pressure (P =.033) and a lower end diastolic velocity in the central retinal artery (P =.0093) compared with normals. Mean ocular perfusion pressure correlated positively with end diastolic velocity in the ophthalmic artery (R = 0.66, P =.002) and central retinal artery (R = 0.74, P <.0001) and negatively with resistivity index in the ophthalmic artery (R = -0.70, P =.001) and central retinal artery (R = -0.62, P =.003) in patients with deteriorating glaucoma. Such correlations did not occur in patients with glaucoma with stable visual fields or in normal subjects. The correlations were statistically significantly different between the study groups (parallelism of regression lines in an analysis of covariance model) for end diastolic velocity (P =.001) and resistivity index (P =.0001) in the ophthalmic artery, as well as for end diastolic velocity (P =.0009) and resistivity index (P =. 001) in the central retinal artery. CONCLUSIONS: The present findings suggest that alterations in ocular blood flow regulation may contribute to the progression in glaucomatous damage.

Aged↗

PubMed2000

Interocular difference in progression of glaucoma correlates with interocular differences in retrobulbar circulation.

PURPOSE: To evaluate the correlation between interocular difference in progression of glaucomatous damage and interocular differences in retrobulbar blood flow. METHODS: On the basis of a retrospective analysis of visual fields, progressive damage was identified in 20 patients with primary open-angle glaucoma. As a parameter of interocular difference in progression of visual field damage, the angle (gamma) between the regression lines of the visual field index mean defect over time per eye was calculated for each subject. The relationship between the angle gamma and interocular differences in intraocular pressure and retrobulbar color Doppler imaging parameters was analyzed by a multiple linear regression analysis in a stepwise forward approach. RESULTS: With larger interocular differences in progression of glaucomatous damage, lower mean blood flow velocities in the ophthalmic artery (partial r = -.69; P <. 0016), higher resistivity indices in the central retinal artery (partial r =.48; P <.0456), and higher peak systolic velocities in the ophthalmic artery (partial r =.52; P <.0285) were noted in the eyes with more marked progression of damage (multiple r =.71; P <. 0099). Interocular differences in progression of visual field damage were not related to intraocular pressure or extent of visual field damage. CONCLUSION: Independent of the extent of the interocular difference in glaucomatous damage and intraocular pressure, interocular difference in progression of glaucomatous visual field damage correlates with interocular difference in retrobulbar hemodynamic parameters.

Blood Circulation↗

PubMed2000

Interocular differences in optic disc topographic parameters in normal subjects.

PURPOSE: To test the interocular differences in optic disc topography in normal subjects by means of confocal scanning laser ophthalmoscopy. METHODS: Topographic measurements of the optic disc were evaluated by means of confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph) in 314 eyes of 157 healthy volunteers. The examination was started randomly either with the right eye or the left eye. Differences between right and left eyes in disc area, cup area, cup volume, cup/disc area ratio, rim area, rim volume, maximum cup depth, cup shape measure, retinal nerve fiber layer thickness, and retinal nerve fiber cross section area for 360 degrees and for the temporal and nasal regions of the optic nerve head were evaluated by means of Student t-test. The same parameters were assessed in a subgroup of 80 elderly (age> 50 years) healthy subjects. Holm's sequentially rejective method was used for significance correction of multiple comparisons. RESULTS: Significant interocular differences in the average retinal nerve fiber layer thickness (p = 0.0010) and retinal nerve fiber layer cross section area (p = 0.0036) were found, with the right eye showing, on the average, lower values. The left eye showed a larger retinal nerve fiber layer thickness in 94 subjects (59.87%) and a larger retinal nerve fiber cross section area in 101 subjects (64. 33%). In the temporal optic disc area there were no statistically significant differences in topometric data (p> 0.05). In the nasal area, significant interocular differences in the retinal nerve fiber layer thickness (p = 0.0002) and retinal nerve fiber layer cross section area (p = 0.0003) were found. Similar results were found when the group of subjects older than 50 years was considered. CONCLUSIONS: This study demonstrates systematic interocular differences in optic disc topometric data. Such a finding, be it due to methodological or biological reasons, should be taken in consideration in clinical trials.

Adolescent↗

PubMed1999

Is vascular regulation in the central retinal artery altered in persons with vasospasm?

OBJECTIVE: To assess the relation between ocular perfusion pressure and blood flow velocity in the central retinal artery in patients with acral vasospasm. SUBJECTS AND METHODS: Eighteen otherwise healthy subjects with acral vascular dysregulation, as demonstrated by nail-fold capillaroscopy, and 18 age- and sex-matched healthy volunteers without vasospasm were recruited. After subjects had rested for 20 minutes in a supine position, intraocular pressure and blood flow velocity in the central retinal artery were determined by applanation tonometry and color Doppler imaging, respectively. The peak systolic velocity, end-diastolic velocity, and resistivity index were assessed. Correlations between the mean ocular perfusion pressure (2/3 x [2/3 x diastolic blood pressure + 1/3 x systolic blood pressure] - intraocular pressure) and blood flow velocities in the central retinal artery were determined by the Pearson linear correlation factor. The Student t test was used to evaluate differences between controls and subjects with vasospasm. RESULTS: The mean +/- SD ocular perfusion pressure was 42.0 +/- 7.4 mm Hg in the group with vasospasm and 47.1 +/- 6.5 mm Hg in the control group (P= .04). In the subjects with vasospasm, the peak systolic and end-diastolic velocities and the resistivity index of the central retinal artery correlated significantly with the mean ocular perfusion pressure (R = 0.49, P = .04 P = .01; and R = -0.67, P = .002, respectively). Such correlations were not found in the control group. CONCLUSIONS: An altered blood flow regulation is suggested in the ocular circulation of patients with acral vasospasm.

Adult↗

PubMed1999

Physiology of perfusion as it relates to the optic nerve head.

Blood flow in the optic nerve has been demonstrated to be autoregulated, and, thus, within certain limits, to be independent of the local perfusion pressure. As in the brain, a close coupling of neuronal activity and optic nerve head blood flow has been demonstrated. A number of regulatory systems and factors participate in the regulation of vascular tone in various organs, including the optic nerve. Metabolic and myogenic mechanisms keep local perfusion constant or adapted to the local metabolic needs. Such mechanisms seem to be involved in the regulation of optic nerve blood flow as well. In contrast, neuronal blood flow regulation is of minor importance in the optic nerve. Many of the regulatory modalities induce a response of vascular smooth muscle cells through stimulation of factors produced by the endothelial cell layer. Indeed, endothelial factors are of utmost importance in the regulation of optic nerve blood flow. The facts that there is a basal formation of nitric oxide, which leads to an active dilation of the ocular vasculature, and that endothelin-1 decreases blood flow to the anterior optic nerve in a dose-dependent manner suggest that alterations in these regulatory mechanisms might be relevant for optic nerve blood flow alterations as they relate to glaucomatous optic neuropathy. It is hoped that a detailed knowledge of blood flow regulation in the optic nerve might initiate new treatment modalities in optic neuropathies that are hemodynamic and vascular in nature.

Animals↗

PubMed1999

Fludrocortisone in the treatment of systemic hypotension in primary open-angle glaucoma patients.

BACKGROUND: Fludrocortisone is a potent mineralocorticoid, which has no known direct vasoactive properties, and is the first-line drug for treatment of orthostatic hypotension. The present study evaluated the systemic hemodynamic effects of fludrocortisone treatment in glaucoma patients. PATIENTS AND METHODS: A retrospective analysis of the charts of glaucoma patients of the University Eye-Clinic Basel was performed. Twenty-two patients with open-angle glaucoma under treatment with fludrocortisone were selected. The selected patients had one 24-h blood pressure recording immediately prior to treatment with fludrocortisone and one recording at least 2 months after starting the treatment. Parallel to blood pressure recordings, diurnal intraocular tension curve recordings and visual field testings were carried out. In addition, twelve patients also had nail-fold video-capillaroscopy. RESULTS: IOP and visual fields remained stable. The average values for all systemic blood-pressure readings showed an improvement in the follow-up compared to primary examination. Mean (+/- SD) night-to-day ratio ('nocturnal dips') of systolic, diastolic and mean arterial blood pressure decreased from 13.6 +/- 4.3%, 16.9 +/- 5.2% and 15.9 +/- 3.5%, respectively, to 9.9 +/- 5.9% (p = 0.01), 13.2 +/- 4.3% (p = 0.044) and 11.7 +/- 3.9% (p = 0.0004). Baseline capillary blood-flow velocity increased and capillary blood-flow standstill time after cold provocation decreased significantly under fludrocortisone therapy. CONCLUSION: Hemodynamic parameters show a tendency towards improvement in a magnitude which might be of clinical relevance.

Blood Flow Velocity↗

PubMed1999

Is corneal temperature correlated with blood-flow velocity in the ophthalmic artery?

PURPOSE: To evaluate the correlation of blood-flow velocities in the ophthalmic artery and corneal temperature in normal subjects and glaucoma patients. METHODS: Corneal temperature was measured on both eyes by means of the THI-500 non-contact infrared thermometer in 18 healthy volunteers and in 18 age and sex matched open-angle glaucoma patients. In these subjects, blood flow velocity was assessed by means of color Doppler imaging (CDI) in both ophthalmic arteries. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistivity index (RI = [(PSV-EDV)/ PSV]) were computed. RESULTS: Corneal temperature values correlated positively with the ipsilateral values of EDV (R(2) = 0.13, p = 0.028, and R(2) = 0.16, p = 0.017 in the left and the right eyes respectively) and negatively with the ipsilateral values of RI (R(2) = 0.11, p = 0.046 and R(2 ) = 0.11, p = 0.044 in the left and the right eyes respectively) in the ophthalmic artery. In addition, the interocular difference in corneal temperature values were significantly correlated positively with the difference in EDV(R( 2) = 0.30, p = 0. 0005) and negatively with the difference in RI (R( 2) = 0.20; p: 0. 0056). All regression models were statistically comparable between normals and glaucoma patients, as well as between right eyes and left eyes. PSV did not contribute to corneal temperature. CONCLUSIONS: The present study suggests that retrobulbar hemodynamics influence corneal temperature, and that this relationship is comparable in normal subjects and glaucoma patients.

Adult↗

PubMed1999

Asymmetry in intraocular pressure and retinal nerve fiber layer thickness in normal-tension glaucoma.

The etiology of glaucoma is most probably multifactorial. This study intended to investigate the asymmetry in intraocular pressure (IOP) and that in retinal nerve fiber layer (RNFL) thickness in normal-tension glaucoma patients. Two diurnal tension curves, obtained within 3 months and counting at least five IOP readings each, including an early morning IOP measurement upon awaking, were obtained in 15 normal-tension glaucoma patients. None of the patients received IOP-lowering therapy. IOP asymmetry was present in at least three readings and was always in the same direction. The optic nerve was imaged in both eyes in each patient by means of confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph). The interocular difference in RNFL thickness and the RNFL cross-sectional area were correlated with the interocular difference in IOP by means of Spearman's rank correlation factor. Nine female and 6 male normal-tension glaucoma patients (mean +/- SD age was 62. 4 +/- 16.9 years) were included in this study. Interocular IOP asymmetry varied between 0.30 and 4 mm Hg. Strong negative correlations were found between interocular asymmetry in IOP and interocular asymmetry in RNFL thickness asymmetry (R = -0.652, p = 0. 0083) and interocular asymmetry in RNFL cross-sectional area (R = -0. 702, p = 0.0034). The present results demonstrate for the first time a more marked thinning of the neuroretinal nerve fiber layer in the eye with the higher IOP in normal-tension glaucoma patients.

Chronic Disease↗

PubMedDate not supplied

The influence of sex difference in measurements with the Langham Ocular Blood Flow System.

PURPOSE: To assess sex difference and parameters possibly accounting for such a difference in healthy subjects evaluated by means of the Langham Ocular Blood Flow (OBF) System. METHODS: Pulse amplitude of intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) as measured with the Langham OBF System were assessed in 86 healthy men and 69 healthy women. RESULTS: Compared to men, women showed higher POBF (mean +/- SD: 722.6 +/- 152.8 versus 647.8 +/- 164.9 microL/min; P =.0056) and pulse amplitude (mean +/- SD: 2.3 +/- 0.7 versus 2.0 +/- 0.6 mm Hg; P =.0043) values. Sex difference was still significant after correcting for age, refraction, blood pressure, IOP, and pulse rate. Pulse amplitude correlated negatively with pulse rate, and POBF correlated negatively with IOP. Women had higher readings in pulse amplitude and POBF, even after correcting for age, refraction, IOP, blood pressure, and pulse rate. CONCLUSIONS: While using the Langham OBF System, one needs to be aware of sex difference that is independent of other hemodynamic parameters. How the observed difference in POBF is related to ocular blood flow, and how it might influence the preponderance of various ocular diseases in men or women remains to be clarified.

Adolescent↗