Biomedical subjects

L Kagemann

Publications and source records attributed to L Kagemann.

At least 19 recordsLinked to original sources

PubMed2004

A comparison of the effects of dorzolamide/timolol fixed combination versus latanoprost on intraocular pressure and pulsatile ocular blood flow in primary open-angle glaucoma patients.

PURPOSE: To evaluate the effects of dorzolamide/timolol fixed combination (D/T) compared to latanoprost on intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) in primary open-angle glaucoma (POAG) patients. METHODS: Thirty patients with POAG were randomized in an open-label, cross-over study. Intraocular pressure reduction was achieved by 4 weeks medical therapy with D/T twice daily or latanoprost 0.005% dosed once in the evening. During a 4-week run-in and a 4-week wash-out period between study arms, patients ceased use of all other glaucoma medications and used timolol maleate 0.5% twice daily. Primary efficacy variables were IOP and POBF. RESULTS: There was no difference in baseline IOP and POBF parameters between the two study arms. Both D/T and latanoprost statistically significantly reduced IOP by 4.6 mmHg (p < 0.0001) and 3.75 mmHg (p < 0.0001) and increased POBF by 2.048 microl/second (p = 0.0030) and 2.147 microl/second (p = 0.0009), respectively. Repeated measures anova detected significant changes in POBF with treatment (p = 0.0361). Dorzolamide/timolol fixed combination statistically significantly increased pulse volume by 0.767 microl (p = 0.0087), while latanoprost therapy had no significant effect (p = 0.2407). CONCLUSIONS: Both drugs had similar effects in terms of IOP reduction. Dorzolamide/timolol significantly increased pulse volume while latanoprost had no effect. Further studies are necessary to establish whether the enhancement of choroidal blood flow can prevent glaucoma progression.

Adult↗

PubMed2004

Ocular haemodynamic responses to induced hypercapnia and hyperoxia in glaucoma.

AIM: To determine the ocular haemodynamic response to gas perturbations in glaucoma. METHODS: Intraocular pressure (IOP), systemic systolic and diastolic blood pressure (SBP and DBP), and retrobulbar blood flow velocities, measured by colour Doppler imaging (CDI), were recorded at two visits. CDI was used to measure peak systolic and end diastolic velocities (PSV and EDV) and resistance index (RI) in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCAs). At the first visit, measurements were taken at baseline (B1: breathing room air) and during isoxic hypercapnia (end tidal PCO(2) increased 15% above baseline) in 16 normal subjects and 12 patients with glaucoma. On another day, measurements were repeated at a second baseline (B2) and during hyperoxia (100% oxygen breathing) for 15 normal subjects and 13 glaucoma patients. Baseline systemic data were compared using paired t tests; REANOVA was performed to compare group differences at baseline and to determine the vessel response to each condition. Fisher's LSD was used for post hoc comparison. RESULTS: Baseline OA PSV was lower for the glaucoma than for the normal group (p = 0.047); the groups were otherwise similar at baseline. IOP demonstrated no response to hypercapnia, but reduced during hyperoxia for both the normal subjects (p<0.0001) and glaucoma patients (p = 0.04). During hypercapnia, SBP increased in normal subjects (p = 0.03) and glaucoma patients (p = 0.01); DBP increased in normal subjects (p = 0.021). There was a corresponding increase in ocular perfusion pressure (OPP) for normal subjects (p = 0.01) and glaucoma subjects (p = 0.028), and as a result OPP was included as a covariate in the REANCOVA model. Hypercapnia resulted in increased PSV in the CRA of normal subjects (p = 0.035) and increased PSV and EDV in the SPCAs of glaucoma patients (p = 0.041 and p = 0.030 respectively). Hyperoxia resulted in reduced PSV and EDV in the ophthalmic arteries of normal subjects only (p = 0.001 and 0.031 respectively). CONCLUSIONS: These findings suggest the presence of relative vasoconstriction in glaucoma patients, which is at least partially reversed by hypercapnia.

Adrenergic beta-Antagonists↗

PubMed2004

Reproducibility of circadian retinal and optic nerve head blood flow measurements by Heidelberg retina flowmetry.

BACKGROUND/AIM: The Heidelberg retina flowmeter (HRF) is designed to measure retinal capillary blood flow. Previous studies however showed weak reproducibility of data. The intraindividual reproducibility of circadian HRF measurements was examined in healthy subjects in three locations of the retina. METHODS: 36 healthy volunteers (27.3 (SD 4.3) years) were examined by HRF seven times a day (t0-t6). Using a default window of 10 x 10 pixels, three consecutive measurements were performed in three precise focusing planes: superficial, intermediate and deep layer, peripapillary retina, neuroretinal rim and cup, respectively. Images of identical tissue locations identified by capillary landmarks of each layer were selected to quantify the retinal microcirculation of each volunteer. Means and standard deviations of all flow results of a given subject were calculated, at t0-t6 and the coefficients of variation as a measure of reproducibility. RESULTS: The coefficients of variation ranged between 8.4% and 41.0% in the superficial layer (mean 19.8% (SD 8.4%)), 10.6%, and 43.0% in the intermediate layer (mean 24.0% (SD 8.4%)), and 9.9% and 84.0% (mean 29.6% (SD 15.8%)) in the deep layer. CONCLUSIONS: These data show the best reproducibility of measurements in the superficial layer followed by the intermediate and the deep layer. Clinically, this is an unsatisfactory intraindividual reproducibility of flow values in each studied layer.

Adult↗

PubMed2004

Reproducibility of the Heidelberg retinal flowmeter in determining low perfusion areas in peripapillary retina.

AIM: To evaluate the interobserver variability and retest reproducibility of confocal scanning laser Doppler flowmeter in measuring capillary perfusion of the peripapillary retina. METHODS: Blood flow measurements were performed in one eye of 10 normal subjects by two investigators on two different days (visits). Five separate measurements of the peripapillary blood flow parameters were recorded by each observer at each visit. The Heidelberg retina flowmeter was used to record capillary perfusion in a 2560x640 microm area of the superotemporal peripapillary region and pixel by pixel analysis was done from an area adjacent to the optic disc, with a minimum of 1600 pixels. The percentage of pixels with less than 1 arbitrary unit of flow (no flow) and 10, 25, 50, 75, 90th percentiles of flow values was calculated. Interobserver measurements were compared by paired t test. Intraclass correlations (ICC) were used to determine the interobserver variability and retest reproducibility of the measurements. Intrasession coefficients of variations (CV) were also calculated. RESULTS: There were no statistically significant differences between the two observers for all measurements and between visits for the percentage of pixels with no flow. ICC was 66% (range 57.09%-77.1%) for pixels with no flow. For the 10, 25, 50, 75, 90th percentiles of flow the ICC was 63.07% (53.91%-77.81%), 71.3% (64.23%-80.85%), 72.61% (66.02%-78.96%), 65.86% (58.53%-74.77%), and 60.05% (54.34%-70.06%), respectively. CV was 16.59%, 11.47%, 9.32%, 9.03%, 11.58%, and 16.05% for the percentage of no flow pixels and the 10, 25, 50, 75, 90th percentiles of flow, respectively. CONCLUSIONS: The Heidelberg retinal flowmeter allows reproducible measurements of all levels of capillary perfusion areas when pixel by pixel analysis is used.

Capillaries↗

PubMed2003

Blood flow per unit retinal nerve fibre tissue volume is lower in the human inferior retina.

AIM: To determine if perfusion per unit tissue volume of retinal nerve fibre layer and optic nerve head in the inferior sector is lower than in the superior sector. METHODS: Heidelberg retinal tomogram (HRT) for topographic measurement of optic nerve head and retinal nerve fibre layer and Heidelberg retinal flowmeter (HRF) for retinal blood flow were performed on 19 normal healthy subjects. Measurements from the superior and inferior sectors were compared. The perfusion/nerve fibre ratio (PNR); the blood flow per unit retinal nerve fibre tissue volume, was calculated in each sector with a formula; HRF flow measurements divided by HRT measurements. RESULTS: Retinal nerve fibre layer thickness in the inferior retina was significantly higher than in the superior retina (p<0.05). There were, however, no differences in retinal blood flow between the superior and inferior retinal sectors. The PNR in the inferior sector were significantly lower than in the superior sector (p=0.047 for HRF mean flow/rim volume and p = 0.0282 for HRF 75th percentile flow/rim volume). CONCLUSIONS: The inferior sector of retinal nerve fibre layer and optic nerve head may have lower blood flow per unit nerve tissue volume compared to the superior sector. This result suggests that the inferior sector is more vulnerable to elevated intraocular pressure (IOP) and ischaemic insults in glaucomatous optic neuropathy.

Adult↗

PubMed2003

The effects of dorzolamide on choroidal and retinal perfusion in non-exudative age related macular degeneration.

AIM: To comprehensively evaluate the effects of dorzolamide on the choroidal and retinal circulation in patients with age related macular degeneration (AMD). METHODS: In this randomised, double masked, parallel study, 36 non-exudative AMD patients were randomised in a 2 to 1 fashion to placebo versus topical dorzolamide and underwent assessment of their choroidal and retinal circulation. Scanning laser ophthalmoscope indocyanine green angiograms (ICGA) were analysed by a new area dilution analysis technique. Four areas in the perifoveal region and two areas in the temporal peripapillary region were evaluated by plotting intensity of fluorescence of each area over time. The means of the choroidal filling times and the heterogeneity of the filling times were assessed. Scanning laser ophthalmoscope fluorescein angiography (FA) was evaluated for retinal arteriovenous passage (AVP) times by plotting intensity of fluorescence of retinal vessels over time. Assessment was performed at baseline and at 4 months. RESULTS: Compared to placebo, AMD patients treated with dorzolamide showed a significantly increased rapidity of choroidal filling in the superior and inferior peripapillary regions (p=0.007, p=0.02, respectively). No significant difference in choroidal filling times was found in any of the perifoveal areas (p=0.9). Also, on FA assessment, treatment with dorzolamide showed no statistical differences in AVP times (p=0.19). CONCLUSIONS: Dorzolamide may increase peripapillary choroidal perfusion in non-exudative AMD patients. Further studies are merited.

Aged↗

PubMed2002

The first technique for non-invasive measurements of volumetric ophthalmic artery blood flow in humans.

AIM: To validate the first non-invasive measurements of volumetric ophthalmic artery blood flow in humans. METHODS: The ophthalmic arteries of healthy normal adults were examined by Advanced Technology Laboratories (ATL, a subsidiary of Phillips Medical Systems Inc) high definition imaging (HDI) 5000 colour Doppler imaging ultrasound with a 5-12 MHZ probe. A group of 14 subjects for experiment 1 and a group of 10 subjects for experiments 2 and 3 were selected, with the examined eye chosen randomly. Peak systolic velocities (PSV) and end diastolic velocities (EDV) of the ophthalmic artery and central retinal artery were measured and recorded. Cineloops (cinegraphic videos) of the ophthalmic arteries were then recorded with the ATL HDI 5000 and values for ophthalmic artery blood flow were produced offline using experimental analysis software. Multiple regression analysis was used to compare blood flow measurements with PSV and EDV measurements in the ophthalmic artery. In two follow up experiments, intraobserver variation in obtaining cineloops and the interanalyser variability in cineloop analysis were studied. RESULTS: Volumetric flow correlated with ophthalmic artery PSV and EDV (p = 0.02, r(2) = 0.5). There was no correlation with the cental retinal artery. The intraobserver coefficient of variation in obtaining cineloops was 29.89% for blood flow, 19.07% for diameter, and 22.27% for velocity. The coefficients of variation of the measurements of the two cineloop analysers were 40.21% for blood flow, 22.71% for diameter, and 26.34% for velocity. CONCLUSION: Cineloop analysis produces ophthalmic artery flow measurements which correlate with PSV and EDV, suggesting validity. The intraobserver variation and cineloop analyser variation were found to be in the acceptable range.

Adult↗

PubMed2001

Detector sensitivity influences blood flow sampling in scanning laser Doppler flowmetry.

PURPOSE: To establish the effect of photodiode sensitivity on the DC (brightness) value and the resultant blood flow measurements of retina and rim tissue using a scanning laser Doppler flowmeter (SLDF). METHODS: The sample consisted of one eye of each of 15 healthy subjects (mean age 27.8 +/- 6.1 years). Using the Heidelberg Retina Flowmeter (HRF), three 10-deg images of the superior temporal retina and three further images of the superior temporal rim were acquired for each of five DC bands: band 1: 30-70; band 2: 70-110; band 3: 110-150; band 4 150-190; band 5: 190-230. Retinal blood volume, flow and velocity were determined for each image using a 10 x 10 pixel square grid located at a predetermined location on the retina and rim for each subject. Following image acquisition, the DC values corresponding to each pre-assigned retinal or rim location were determined. The mean and standard deviation were determined for the blood flow parameters within each DC band for each subject in both locations. Analysis of variance was used to identify significant change in the data as a function of the DC value (P<0.05). RESULTS: Analysis of variance revealed that retinal blood flow measures acquired within DC band 5 resulted in significantly lower measures of blood flow and velocity (P=0.035 and P=0.049 respectively) than at lower DC values. Band 5 values of flow, volume and velocity in the neuroretinal rim were also significantly low (P=0.016, P= 0.003 and P=0.026 respectively). Peak neuroretinal rim blood flow was recorded when the DC value was between 70 and 110. For blood flow measurement at the retina and neuroretinal rim the DC value should not exceed 190. CONCLUSION: Photodiode sensitivity as indicated by the DC value affects measurements of ocular blood flow using the HRF.

Adult↗

PubMed2001

Effect of dorzolamide timolol combination versus timolol 0.5% on ocular bloodflow in patients with primary open-angle glaucoma.

PURPOSE: Addition of dorzolamide to timolol in primary open-angle glaucoma shows augmented reduction of intraocular pressure. It is unknown as yet if addition of dorzolamide will alter hemodynamics. METHODS: Fifteen patients with primary open-angle glaucoma were placed on a medication-dependent 1-week to 4-week washout that included maintenance on timolol. After washout, baseline measurements were taken (timolol). They were studied after a month on timolol or dorzolamide-timolol (Cosopt; Merck, Inc, Whitehouse Station, New Jersey), with the second drug preceded by another month of timolol maintenance and second baseline measurements. At each visit, visual function, intraocular pressure, and ocular hemodynamics were monitored, including indocyanine green and fluorescein angiography and color Doppler imaging. RESULTS: Cosopt significantly reduced intraocular pressure (14.7 to 13.4 mm Hg, P <.05) and increased arteriovenous passage time (superior temporal artery) of fluorescein dye (2.13 to 1.76 seconds, P =.01) but had no effect on visual function. CONCLUSIONS: When compared with timolol in primary open-angle glaucoma, Cosopt augments ocular tension reduction and reduces the amount of time required for blood to pass through the superior retinal vasculature.

Adrenergic beta-Antagonists↗

PubMed2001

Simultaneous management of blood flow and IOP in glaucoma.

Factors other than intraocular pressure (IOP) elevation must be involved in initiation and progression of glaucoma. An additional element in disease causation may be ischemia in the retina and optic nerve head. Ischemic damage to neurons in the CNS is similar mechanistically and histopathologically to changes seen in glaucoma. Further, glaucoma patients with normal IOP show clear evidence for cerebral and ocular ischemia. Aging and atherosclerosis reduce the ability of the eye to autoregulate blood flow when ocular perfusion pressure changes: the dependence of blood flow on perfusion pressure links ischemia to IOP. Consequently, neuroprotective treatments for glaucoma should be designed to both reduce IOP and improve ocular nutrient delivery.

Aging↗

PubMed2001

Effect of brimonidine tartrate on ocular hemodynamics in healthy volunteers.

While alpha2-adrenergic agonists, such as brimonidine tartrate, significantly reduce the intraocular pressure (IOP), the presence of vasoconstrictor postsynaptic alpha2 receptors on vascular smooth muscle raise the possibility that brimonidine could potentially compromise ocular blood flow. Consequently, the ocular hemodynamic effects of brimonidine were studied in normal subjects. Twelve healthy volunteers were included in this prospective, double-masked, placebo controlled, crossover-designed clinical trial. They received either brimonidine tartrate 0.2% or placebo b.i.d. for 2 weeks. Goldmann tonometry and color Doppler imaging (CDI) were performed at baseline, at 2 hr, 1 week, and 2 weeks after the treatment. Fundus angiography using a scanning laser ophthalmoscope was performed at baseline and 2 weeks after treatment to determine retinal arteriovenous passage time. Brimonidine lowered IOP at 2 hr, 1 week, and 2 weeks (p = 0.058, p = 0.031, and p = 0.022, respectively). Brimonidine did not affect the retrobulbar arterial velocities measured by CDI, nor retinal arteriovenous passage time. In conclusion, two-week treatment with brimonidine reduces IOP and does not reduce the bulk retinal or retrobulbar arterial perfusion in young healthy volunteers.

Administration, Topical↗

PubMed2001

Intraocular pressure and photorefractive keratectomy: a comparison of three different tonometers.

PURPOSE: To evaluate the intraocular pressure (IOP) with three different instruments, Goldmann applanation tonometer (GAT), noncontact tonometer, and Tono-Pen after photorefractive keratectomy (PRK) for myopia. METHODS: A prospective case series study to evaluate preoperative and postoperative IOP measurements of 149 eyes at 12 months. We performed GAT, noncontact tonometry, Tono-Pen central, and Tono-Pen temporal periphery measurements. We also performed measurements of the central corneal thickness (CCT) by ultrasonic pachymetry and keratometry. Pre-operative IOP reading served as control for all studies. RESULTS: After PRK, IOP reading was significantly reduced in the treated eyes when compared with the control measurements (11.87+/-1.73 vs. 13.37+/-1.52 mm Hg, p<0.0001 with GAT; 12.07+/-1.6 vs. 13.51+/-1.59 mm Hg, p<0.0001 with noncontact tonometer; 12.18+/-1.6 vs. 13.48+/-1.55 mm Hg, p<0.0001 with Tono-Pen central; 13.48+/-1.65 vs. 13.71+/-1.56 Hg, p<0.0104 with Tono-Pen temporal periphery). There was also a significant correlation between IOP reading changes measured by GAT, noncontact tonometer, Tono-Pen central, and change of CCT and between reduction of IOP reading and keratometry (r2>0.39, p<0.0001 for each). The correlation between IOP reading change by Tono-Pen temporal periphery and CCT was also significant but r2 value was only 0.034. Tono-Pen temporal periphery postoperative IOP measurements had the best correlation with preoperative GAT IOP (r2 = 0.57, p<0.0001). CONCLUSIONS: PRK reduced IOP reading as measured by GAT, noncontact tonometer, and Tono-Pen central; less so when measured by Tono-Pen temporal periphery. Early detection of glaucoma and IOP follow-up in glaucoma patients may be done best by peripheral Tono-Pen measurements over the nonablated cornea.

Adult↗

PubMed2001

New neuroretinal rim blood flow evaluation method combining Heidelberg retina flowmetry and tomography.

AIM: Accurate Heidelberg retina flowmeter (HRF) measurements require correct manual setting of the HRF photodetector sensitivity. The neuroretinal rim produces a weak signal relative to the peripapillary retina. A newly developed HRF alignment and sensitivity protocol, capable of accurate rim measurement, was investigated. METHODS: 18 eyes of nine healthy volunteers were examined by HRF. Three images of each eye were taken using three different imaging methods. Method 1: a conventional image (optic nerve head centred image with photodetector sensitivity optimised for the strong signal from the peripapillary retina); method 2: the setting of method 1 with photodetector sensitivity optimised for the weak signal from the rim; and method 3: the setting of method 2 with the temporal rim margin tangent to the lateral image border to remove the overpowering signal from the temporal peripapillary retina. The neuroretinal rim was defined by the Heidelberg retina tomograph (HRT). Blood flow and reflectivity values (DC component) in the rim area were compared for the three methods using pointwise analysis. Coefficients of variation of repeated measurements in 12 subjects have been calculated for method 3. RESULTS: The neuroretinal rim area measured by method 1 had a significantly lower brightness compared with method 2 and 3 (p=0.0002 and p=0.0002, respectively). Method 2 provided proper sensitivity for the weak signals of the rim area based on rim tissue DC values; however, this sensitivity setting was too high for the strong signal from the peripapillary retina. Method 3 avoided the strong peripapillary signal with the proper signal from the rim and provided significantly higher flow values of the rim area at 75 and 90 percentile pixels (p=0.0065 and p=0.0038 respectively) compared with method 2. Interobserver repeatability ranged from 16.85% to 21.96% for the different parameters. CONCLUSIONS: Method 3 provides an accurate and reproducible flow measurement of the neuroretinal rim area through proper sensitivity for the weak rim signal, alignment, and removal of the strong temporal signal from the image. This new method is recommended to improve accuracy of blood flow measurement in the neuroretinal rim.

Adolescent↗

PubMed2001

Photodetector sensitivity level and heidelberg retina flowmeter measurements in humans.

PURPOSE: In vitro models suggest that Heidelberg retina flowmeter (HRF) measurements are affected by changes in photodetector sensitivity. We measured blood flow in a single volume of human retinal tissue in vivo at various sensitivity (DC) levels. METHODS: The peripapillary retinal regions of 12 normal subjects were examined by HRF under five different sensitivity settings: (1) average DC range below 100; (2) average DC range below 125; (3) average DC range near 150 (normal sensitivity); (4) average DC range above 175; and (5) average DC range above 200 or extremely overexposed. The distributions of flow values were examined by pointwise analysis. All pixels from a common tissue location were analyzed, and the effect of their brightness on the flow measurement was evaluated by ANOVA with Fisher's protected least significant difference model. RESULTS: ANOVA analysis of image DC level showed that significantly different DC levels were achieved for each of the five sensitivity settings (P < 0.0001). Flow values decreased with increasing DC for each of the 25th percentile, 50th percentile (P: < 0.0001 for each), 75th percentile (P: = 0.0026), 90th percentile (P: = 0.0216), and mean (P: = 0.0004) flow values. The percentage of pixels with values of zero (avascular tissue) increased with increasing photodetector sensitivity (P< 0.0001). CONCLUSIONS: Improper sensitivity settings alter the detected percentage of avascular tissue and the blood flow measurements in tissue containing capillaries. Consistent assessment of retinal blood flow requires consistent photodetector sensitivity settings between longitudinal images.

Adult↗

PubMed2001

Ocular blood flow measurements and their importance in glaucoma and age-related macular degeneration.

This survey of methods for assessing ocular hemodynamics in glaucoma and age-related macular degeneration is not complete, but it does cover those likely to be encountered in the literature. A fundamental problem in getting to grips with the ocular blood flow literature is the difficulty in comparing the results of similar studies employing different assessment techniques. As evident from the discussion above, each technique evaluates a portion of the ocular circulation in a distinct way. Some of the methods overlap with regard to the tissues that can be used for examination, while others are directed at entirely different parts of the ocular vasculature. Despite these difficulties, hemodynamic studies of glaucoma and AMD are likely to grow in importance. On the basis of accumulating epidemiological and clinical evidence, it is becoming apparent that intraocular pressure is not the sole etiological factor in glaucoma, and retinal pigment epithelium senescence is not the sole etiological factor in AMD. Circumstantial evidence of vascular involvement in glaucoma and AMD has now been bolstered by experimental evidence. If the current pace of refinement of newly established technologies for evaluating ocular blood flow is maintained, they will soon be ready for deployment in the clinic. The only problem is the availability of expensive instruments and trained personnel. The ultimate beneficiaries of work in this area will not be researchers, but patients.

Angiography↗

PubMed2001

Transpupillary thermotherapy for subfoveal occult choroidal neovascularization: effect on ocular perfusion.

PURPOSE: To perform a descriptive analysis of the effects on ocular blood flow of transpupillary thermotherapy (TTT) for occult subfoveal choroidal neovascular membranes (CNVMs) in age-related macular degeneration (AMD). METHODS: Eleven subjects with occult subfoveal CNVM due to AMD were assessed in a masked fashion by color Doppler imaging (CDI) within 24 hours before, 24 hours after, and 1 month after undergoing TTT. RESULTS: In the posterior ciliary arteries (PCAs), there were no statistically significant changes observed in the peak systolic velocity (PSV), end diastolic velocity (EDV), or resistive index (RI) at 24 hours. At 1 month, the mean EDV decreased 36% (P = 0.0105) and the mean RI increased 3.8% (P = 0.0305) in the nasal PCA. Although there was a similar trend in the temporal PCA, the differences did not reach statistical significance. In the central retinal artery (CRA), the mean PSV decreased 16% (P = 0.0137), and the mean EDV decreased 21% (P = 0.0222) at 24 hours after treatment. There were no statistically significant differences in the CRA blood flow indices at 1 month after treatment. In the ophthalmic artery, there were no statistically significant differences observed in the mean PSV, EDV, or RI at 24 hours or 1 month after treatment. CONCLUSIONS: TTT is associated with transiently decreased volumetric blood flow in the retinal circulation 24 hours after treatment. In the posterior ciliary arteries that supply the choroid, there were no changes observed at 24 hours, but at 1 month, there was a decrease in the mean EDV and an increase in the RI in the nasal and temporal PCAs, reaching statistical significance in the nasal PCA only. This study suggests that TTT could lead to alterations in choroidal blood flow, as assessed by CDI. Further study is warranted.

Aged↗

PubMed2000

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↗

PubMed2000

Regional differences in optic disc and retinal circulation.

PURPOSE: To determine regional differences in the circulation of the optic disc, the peripapillary choroid and the retinal vessels using the techniques of computerized image analysis and fluorescein angiography. METHODS: Ten young normal subjects were studied. Fluorescein angiography was performed with a scanning laser ophthalmoscope. The rate of filling of fluorescein or slope was measured in the four quadrants of the optic disc, the peripapillary choroid and the major retinal arteries and veins. A total of 125 points was measured from each image of the fluorescein angiograms for a total of 20 to 30 images. Retinal vessel width was measured using computerized image analysis. RESULTS: Comparison of the rates of filling of fluorescein or slopes showed significant differences from zero among the four quadrants of the optic disc (p= 0.01 to <0.02), of the peripapillary choroid (p=0.01 to <0.05) and among the major retinal arteries (p=0.01 to <0.02) and retinal veins (p=0.02 to <0.05). No significant differences were noted between the quadrants for retinal arterial width with the retinal veins only showing a significant difference between the inferior nasal and inferior temporal vein (p=0.02 to <0.05). CONCLUSION: Evaluation of the circulation of the optic disc, retina, and peripapillary choroid should take into account regional differences among these structures.

Adult↗