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Biomedical subjects

Ehud Rechtman

Publications and source records attributed to Ehud Rechtman.

11 recordsLinked to original sources
PubMed2006

A comparative analysis of the effects of the fixed combination of timolol and dorzolamide versus latanoprost plus timolol on ocular hemodynamics and visual function in patients with primary open-angle glaucoma.

AIMS: The aim of this study was to assess the effects of fixed combination of timolol and dorzolamide and latanoprost plus timolol on retinal, choroidal, and retrobulbar hemodynamics and visual function in primary open-angle glaucoma (OAG) subjects. METHODS: Sixteen (16) OAG patients (age, 63.5 +/- 10.8 years; 9 male) were evaluated in a randomized, crossover, double-blind study design after 4 weeks of treatment of latanoprost with timolol and fixed combination of timolol and dorzolamide. After randomization, 9 right eyes and 7 left eyes were included in the hemodynamic portion of the study. Measurements included: adverse events check, visual acuity, contrast sensitivity, blood pressure, heart rate, intraocular pressure (IOP), and fundus examination. Ocular blood flow was assessed using confocal scanning laser Doppler flowmetry, color Doppler imaging, and scanning laser ophthalmoscopy. RESULTS: Both therapies were effective at lowering IOP, whereas there was no statistically significant difference between latanoprost plus timolol and the fixed combination of timolol and dorzolamide (13.9% and 12.2% reduction, respectively; P = 0.5533). Fixed combination of timolol and dorzolamide significantly increased central retinal artery end diastolic blood flow velocity (P = 0.0168) and lowered resistance to flow (P = 0.0279). Temporal posterior ciliary artery peak systolic and end diastolic velocities were significantly increased with the fixed combination of timolol and dorzolamide (P = 0.0125 and 0.0238, respectively). Latanoprost plus timolol had no significant effects on ocular blood flow during 4 weeks of treatment. There were no statistically significant differences in adverse events, blood pressure, heart rate, visual acuity, contrast sensitivity scanning laser ophthalmoscopy, or Heidelberg Retinal Flowmeter for any treatment period. CONCLUSIONS: Fixed combination of timolol and dorzolamide therapy might increase blood flow in OAG patients while attaining a similar IOP reduction compared to latanoprost plus timolol. Visual function, however, was not different in this short-term comparison between the two treatments.

Adrenergic beta-Antagonists↗
PubMed2006

Automatic retinal oximetry.

PURPOSE: To measure hemoglobin oxygen saturation (SO(2)) in retinal vessels and to test the reproducibility and sensitivity of an automatic spectrophotometric oximeter. METHODS: Specialized software automatically identifies the retinal blood vessels on fundus images, which are obtained with four different wavelengths of light. The software calculates optical density ratios (ODRs) for each vessel. The reproducibility was evaluated by analyzing five repeated measurements of the same vessels. A linear relationship between SO(2) and ODR was assumed and a linear model derived. After calibration, reproducibility and sensitivity were calculated in terms of SO(2). Systemic hyperoxia (n = 16) was induced in healthy volunteers by changing the O(2) concentration in inhaled air from 21% to 100%. RESULTS: The automatic software enhanced reproducibility, and the mean SD for repeated measurements was 3.7% for arterioles and 5.3% venules, in terms of percentage of SO(2) (five repeats, 10 individuals). The model derived for calibration was SO(2) = 125 - 142 . ODR. The arterial SO(2) measured 96% +/- 9% (mean +/- SD) during normoxia and 101% +/- 8% during hyperoxia (n = 16). The difference between normoxia and hyperoxia was significant (P = 0.0027, paired t-test). Corresponding numbers for venules were 55% +/- 14% and 78% +/- 15% (P < 0.0001). SO(2) is displayed as a pseudocolor map drawn on fundus images. CONCLUSIONS: The retinal oximeter is reliable, easy to use, and sensitive to changes in SO(2) when concentration of O(2) in inhaled air is changed.

Humans↗
PubMed2005

The role of optic nerve blood flow in the pathogenesis of glaucoma.

Many theories have surfaced regarding the exact mechanisms behind glaucomatous damage, but the complex nature of the disease and the inaccessibility of the internal structures of the human eye have limited current knowledge. Increased intraocular pressure is the risk factor most often associated with glaucomatous optic neuropathy; ischemic insult to the optic nerve has also been suggested as a possible cause of cellular damage. The aim of this review is to cover the possible role of optic nerve head hemodynamics in the pathogenesis of glaucoma.

Aging↗
PubMed2003

Reduced cerebrovascular blood flow velocities and vasoreactivity in open-angle glaucoma.

PURPOSE: To compare cerebral blood flow velocities between open-angle glaucoma (OAG) patients and controls, at baseline and during hyperoxia. DESIGN: Observational cohort study. METHODS: A prospective study was conducted in a single institution. Sixteen OAG patients and 15 normal subjects, matched for age, were enrolled. Patients and controls were studied at baseline, while breathing room air, and during 100% oxygen breathing. The eye with the more severe visual field defect was chosen in glaucoma patients, while in controls, the study eye was chosen randomly. Subjects with history of diabetes, cardiovascular, or respiratory disease were excluded. Measurements included brachial arterial pressure, heart rate, intraocular pressure and transcranial Doppler (TCD). Mean and peak velocity and pulsatility index of the ipsilateral middle cerebral artery (MCA) were measured by TCD. RESULTS: At baseline, MCA mean and peak systolic blood flow velocities were significantly lower in glaucoma patients compared with controls velocities were significantly lower in glaucoma patients compared with controls (mean velocity: 50.2 vs 65.3 cm/s, P <.05; peak velocity: 74.2 vs 96.8 cm/s, P <.05). Additionally, while hyperoxia significantly decreased both mean and peak systolic velocities in MCA of controls (mean velocity: 65.3 vs 57.7 cm/s, P <.05; peak velocity 96.8 vs 87.9 cm/s, P <.05), it did not cause any significant change in OAG patients. CONCLUSIONS: Glaucoma patients were found to have lower MCA blood flow velocities and an absence of vasoreactivity to hyperoxia, compared with controls. The relationship of these cerebral hemodynamic abnormalities to glaucoma pathogenesis and progression remains to be explored.

Blood Flow Velocity↗
PubMed2003

Intravitreal triamcinolone for choroidal neovascularization in ocular histoplasmosis syndrome.

PURPOSE: To report the effects of intravitreal triamcinolone acetonide injections for subfoveal and juxtafoveal choroidal neovascularization (CNV) in ocular histoplasmosis syndrome. METHODS: In a retrospective analysis, the proportion of eyes that gained >or=5 or lost >or=5 and >or=15 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters, best-corrected visual acuity using ETDRS letter score (VA), greatest linear dimension (GLD), and treatment side effects were assessed. RESULTS: Ten patients (five subfoveal, five juxtafoveal CNV; median follow-up: 17 months; range, 6-41 months) were evaluated. Thirty percent gained >or=5 letters, 20% lost 5 to 14 letters, and 50% maintained stable VA. Overall, mean VA and GLD remained stable. Side effects were transient intraocular pressure elevation and mild cataract development. CONCLUSIONS: Intravitreal triamcinolone acetonide for CNV resulting from OHS was found to be relatively safe and showed good visual outcome for both subfoveal and juxtafoveal CNV. Further studies are warranted to evaluate this treatment.

Adult↗
PubMed2002

Pneumatic retinopexy: results in eyes with classic vs relative indications.

OBJECTIVE: To compare the results of pneumatic retinopexy in 3 groups of eyes with rhegmatogenous retinal detachment. METHODS: In this retrospective, consecutive study, 44 eyes of 44 patients who underwent pneumatic retinopexy were divided into 3 groups: eyes with vitreoretinal abnormalities (group A), pseudopakic or aphakic eyes (group B), and phakic eyes without vitreoretinal abnormalities (group C). RESULTS: Single retinopexy success was achieved in 10 (71%) of 14 eyes in group A, 7 (64%) of 11 eyes in group B, and 16 (84%) of 19 eyes in group C (P=.42). Final success after reoperation was achieved in 13 (93%) of 14 eyes in group A, 10 (91%) of 11 eyes in group B, and in all 19 eyes in group C (P=.44). In group B, the rate of single retinopexy success using cryotherapy was significantly higher (5/5; 100%) than when laser photocoagulation was used (1/5; 20%) (P=.015). The final visual outcome obtained in the 3 groups was similar. There were no significant intergroup differences in either early or late complications. CONCLUSIONS: The best results were achieved in eyes with classic indications for pneumatic retinopexy, though the differences between these results and those in the nonclassic indications were not significant. In pseudophakic or aphakic eyes, the rate of single operation success after cryopexy was significantly higher than the rate after laser photocoagulation.

Adolescent↗
PubMed2002

An update on photodynamic therapy in age-related macular degeneration.

Age-related macular degeneration (AMD) is the leading cause of irreversible loss of central vision in people aged > 50 years in the western world. Until recently, the only proven treatment to reduce the risk of vision loss from its more severe neovascular form was laser photocoagulation, but this treatment was suitable for only 15% of cases. Photodynamic therapy (PDT) with verteporfin was recently proposed to be effective in reducing the risk of visual loss for an estimated 20 - 30% of neovascular AMD patients. This review covers AMD epidemiology, the mechanism of PDT, the 2-year results of the two major clinical studies of PDT with verteporfin, the cost-effectiveness of PDT and the current research status of other drugs for PDT in AMD.

Age Factors↗
PubMedDate not supplied

A review of methods for human retinal oximetry.

Attempts to noninvasively quantify the oxygen saturation of blood within the retinal vasculature date back to the 1950s. This article discusses the various approaches that have been taken to estimate the oxygen saturation in the retinal vasculature. Advantages and limitations of each are discussed. Data from human and animal subjects are also presented.

Humans↗
PubMedDate not supplied

Comparison of ocular hemodynamics measured by a new retinal blood flowmeter and color Doppler imaging.

BACKGROUND AND OBJECTIVE: To compare measurements of a new retinal blood flow device with central retinal artery blood velocity. MATERIALS AND METHODS: One randomly selected eye from each of 13 subjects was examined. Blood flow was measured by laser blood flowmeter and velocity by color Doppler imaging. The correlation between measurements was analyzed using regression analysis where a P value of less than .05 and coefficient of regression values of greater than .5 were considered significant. RESULTS: The laser blood flowmeter produced vessel diameter measurements of 90.1 +/- 18.7 microm (mean +/- standard deviation), velocity of 19.7 +/- 8.06 mm/sec, and flow measurements of 4.24 +/- 2.41 microL/min. Central retinal artery peak systolic velocity, end diastolic velocity, and mean velocity correlated significantly with laser blood flowmeter velocity (P = .01, r = .66; P < .01, r = .77; and P = .003, r = .76, respectively) and flow (P = .01, r = .71; P = .03, r = .6; and P = .01, r = .69, respectively). CONCLUSIONS: The laser blood flowmeter produces retinal artery flow and velocity measurements that correlate with central retinal artery peak systolic velocity end diastolic velocity, and mean velocity measurements. Further validation of the laser blood flowmeter's accuracy in measuring real flow warranted and likely requires more invasive in vivo studies (in animal models). However, this study supports the ability of the laser blood flowmeter to measure retinal blood flow.

Adult↗