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Biomedical subjects

J Schwoerer

Publications and source records attributed to J Schwoerer.

4 recordsLinked to original sources

Indocyanine green angiography in Fundus flavimaculatus.

PURPOSE: To describe the characteristic findings of fundus flavimaculatus (Stargardt disease) as seen on indocyanine green angiography. METHODS: Twelve eyes of 6 consecutive patients with fundus flavimaculatus were studied by fundus color photographs, fluorescein angiography and indocyanine green angiography. RESULTS: Indocyanine green angiography allowed visualization of small, clearly demarcated areas in which hypofluorescence increased over time, leading eventually to a large reticular pattern with small areas of normal-appearing choroid encircled by a well-defined network of hypofluorescent curvilinear lesions. These hypofluorescent flecks were present in all 12 eyes but corresponded only partially to the yellow flecks visible on biomicroscopy of the fundus. The peripapillary area was well preserved on indocyanine green angiography and the periphery did not show any visible abnormalities. CONCLUSIONS: The hypofluorescent curvilinear areas visualized on indocyanine green angiography form a reticular pattern that is similar to the polygonal shape of the watershed zones between terminal choroidal arterioles, which supply the choriocapillaris. These dark areas may reflect choriocapillaris defects secondary to lysis of lipofuscin-engorged retinal pigment epithelial cells. The typical lesions of fundus flavimaculatus thus seem to be situated in areas of least vascular supply. Their absence in the peripapillary area, which benefits from anastomotic vascular connections, would support this hypothesis.

Adult↗

Retinal blood vessel width measured on color fundus photographs by image analysis.

The purpose of this paper was to develop a technique using computerized image analysis to measure the width of retinal arteries and veins on color fundus photographs. The width of the retinal vessel was determined from digitized fundus photographs by programs based on edge detection and boundary tracing. The average vessel width was determined at different distances or eccentricities from the center of the optic disc and using various lengths of vessel segment. Measurements of superior and inferior temporal vessel width for 20 eyes by 2 operators showed that about 75% of the measurements could be obtained without the use of plan points. The average percent coefficient of variation of the measurements was 2.17% for 3 measurements of each vessel. This technique provides a reproducible and objective method for obtaining the following parameters: the edges of the vessel, the length of the vessel segment to be measured, location of the measurement along the vessel and subsequent retinal vessel width. This technique is readily suitable for application to clinical studies particularly clinical trials.

Adult↗

Retinal vessel autoregulation in sickle cell patients.

We tested retinal vessel autoregulation in 16 sickle cell patients and 6 controls by computer-assisted measurements of constriction of the superior and inferior temporal veins and arteries after pure oxygen breathing. Compared to the controls and corrected for age, we found a decrease of vasoconstriction in three of the four vessels measured in the sickle cell group, which was statistically significant only for the superior temporal artery (P 0.009). The number of patients was too small to allow a separate analysis of possible contributory factors within the sickle cell group, such as sickle cell hemoglobin subtype and extent of retinal ischemia. Our findings indicate a factor not yet well known in the pathophysiology of sickle cell disease: an abnormality of local microvascular control.

Adult↗

Acute retinal necrosis: a new pathophysiological hypothesis.

A 76-year-old woman with unilateral acute retinal necrosis had an elevated titer of cytomegalovirus (CMV) antibodies with both in the aqueous humor and serum. The serological pattern indicated recent CMV infection, and the Goldmann-Witmer coefficient comparing aqueous and serum titers was above 4 indicating intraocular production of specific antibodies. The clinical characteristics and results as well as a new possible etiopathogenic hypothesis are presented.

Aged↗