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Biomedical subjects

O Cuzzani

Publications and source records attributed to O Cuzzani.

5 recordsLinked to original sources
PubMed2000

The effect of transmission bandwidth on the quality of ophthalmological still and video images.

We have examined the minimum realtime transmission speed for video-angiography with the Rodenstock scanning laser ophthalmoscope (SLO) with respect to spatial and contrast resolution. An SLO fluorescein video-angiography sequence was recorded using high-quality media and relayed to a remote site at transmission speeds ranging from T3 (4.5 Mbit/s) to 0.125 T (197 kbit/s). Images were compared with each other subjectively by an ophthalmologist and objectively with image processing software. When compared qualitatively there was little difference between the T3 and T1 images. The T1 images scored well on clarity and contrast, while 0.5 T was satisfactory but inferior to T1. Transmission speeds below 0.5 T were inadequate. The digital analysis showed a slight difference between T3 and T1. We calculated that there was up to a 92% loss of resolution at 0.25 T and up to a 98% loss at 0.125 T. Based on our quantitative and qualitative analysis, a T3 line provided the highest bandwidth and best resolution, as expected. However, 0.5 T gave satisfactory results for realtime consultations and appears to be the minimum speed required for ophthalmic purposes, producing few motion artefacts and good resolution.

Cataract Extraction↗
PubMed1997

Modulation of the blood-aqueous barrier by light exposure in patients with uveitis.

OBJECTIVE: To evaluate the effect of light deprivation on flare measurements in patients with uveitis. DESIGN: Prospective study. SETTING: Eye clinic providing tertiary ophthalmic care in Calgary. PATIENTS: Five consecutive patients with a history of long-standing uveitis. INTERVENTIONS: Flare measurements were obtained with the Kowa FC-1000 flare-cell meter before and after 24 hours of monocular occlusion, and before and after wearing sunglasses during waking hours in a 24-hour period. OUTCOME MEASURE: Aqueous flare. RESULTS: A significant decrease in flare was observed after 24 hours of occlusion in all patients (p < 0.01). One patient showed an interesting change in response when her steroid treatment was tapered and subsequently stopped. Two of three patients showed a decrease in flare after wearing sunglasses. CONCLUSIONS: These preliminary results suggest that sunlight causes breakdown of the blood-ocular barrier in certain cases of uveitis. Further investigation is needed to determine the extent and mechanisms of light-induced breakdown of the blood-aqueous barrier as well as the role of sunglasses and anti-inflammatory medications as potential modulators of light-induced inflammation.

Adult↗
PubMed1995

Peroxide-cyclooxygenase interactions in postasphyxial changes in retinal and choroidal hemodynamics.

To test the role of reactive oxygen species and cyclooxygenase products in the retinal hemodynamic changes induced by asphyxia, we measured retinal (RBF) and choroidal blood flows (ChBF), malondialdehyde (MDA), prostaglandin E2 (PGE2), 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), and thromboxane B2 (TxB2) in 1- to 3-day-old pigs treated with saline, the free radical scavengers U-74389F or high-dose allopurinol, the cyclooxygenase inhibitors ibuprofen or indomethacin, or the thromboxane synthase blocker CGS-13080 before and 5 and 60 min after a 5-min period of asphyxia. In saline-treated animals, RBF and ChBF increased 5 min after asphyxia and decreased at 60 min. The increases in RBF and ChBF at 5 min postasphyxia were slightly attenuated by cyclooxygenase blockers and free radical scavengers but not by thromboxane synthase inhibition, whereas all drugs prevented the decreases at 60 min. MDA, TxB2, PGE2, and 6-keto-PGF1 alpha increased 5 min after asphyxia; at 60 min, PGE2 and 6-keto-PGF1 alpha returned to nearly preasphyxial levels, but MDA and TxB2 continued to increase. Cyclooxygenase inhibition prevented the asphyxia-induced rise in MDA, and the free radical scavengers prevented that of prostanoids. In isolated eyecup preparations, H2O2 and cumene hydroperoxide constricted retinal arteries; this effect was blocked by cyclooxygenase and thromboxane synthase inhibitors. The data suggest that during oxidative stresses reactive oxygen species are generated from the cyclooxygenase pathway and, in turn, also activate the synthesis of thromboxane; the latter mediates the oxidative stress-induced ocular vasoconstriction that might trigger the neovascularization of retinopathy of prematurity.

3,4-Methylenedioxyamphetamine↗