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Biomedical subjects

Alon Harris

Publications and source records attributed to Alon Harris.

24 records · Page 2Linked to original sources
PubMed2002

Choroidal perfusion perturbations in non-neovascular age related macular degeneration.

AIM: Choroidal perfusion, affected in age related macular degeneration (AMD), is difficult to objectively assess given the overlying retinal circulation. This study more objectively compared choroidal perfusion parameters in a group with non-neovascular AMD to an unaffected age matched control group. METHODS: 21 non-neovascular AMD subjects and 21 age matched control subjects without evidence of AMD underwent assessment of their choroidal blood flow in a case-control study. Scanning laser ophthalmoscope indocyanine green (ICG) angiograms were analysed by a new area dilution analysis technique. Four areas in the perifoveal region and two areas in the temporal peripapillary retina were evaluated by producing a graph of intensity of fluorescence of each area over time. The mean of the filling times and the heterogeneity of the filling times were assessed. RESULTS: The means of the filling times within the perifoveal regions and the hetereogeneity of the filling times between regions within the same eyes were significantly greater in the AMD patients compared with the control subjects. CONCLUSIONS: Delayed and heterogeneous filling of the choroid was objectively demonstrated in eyes with non-neovascular AMD compared with age matched controls without evidence of AMD, using an area dilution analysis technique applied to ICG angiography.

Aged↗
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

Effects of timolol and dorzolamide on retrobulbar hemodynamics in patients with newly diagnosed primary open-angle glaucoma.

The authors considered a group of patients with newly diagnosed primary open-angle glaucoma studying the effects of a 4-week treatment with timolol or dorzolamide on retrobulbar vessels. Ocular hemodynamics were assessed by means of color Doppler imaging of the ophthalmic artery, the temporal short posterior ciliary arteries (SPCAs) and the central retinal artery. For each vessel, systolic and diastolic blood flow velocities were measured, and the resistivity index (RI) was calculated. The only significant result was a reduction of temporal SPCA RI after dorzolamide treatment in comparison with baseline (p = 0.011). In the same group, dorzolamide treatment had a slight and nonsignificant increase in temporal SPCA diastolic velocity. The resistance decrease observed after dorzolamide treatment in the ciliary circulation may be due to the decrease in intraocular pressure or a possible direct vasodilating effect of the drug.

Adrenergic beta-Antagonists↗
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↗