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Dr. Jaime Roizenblatt

Retinal blood flow measurements in branch retinal vein occlusion using scanning laser doppler flowmetry

Dialogue
Authors: Cesar P. Avila, Jr, MD, Dirk-Uwe Bartsch, PhD, Daniel G. Bitner, MD, Lingyun Cheng, MD, Arthur J. Mueller, MD, Marietta P. Karavellas, MD, and William R. Freeman, MD

Purpose:
To determine capillary blood flow measurements in eyes with branch retinal vein occlusion using a scanning laser Doppler flowmeter.

Methods:
Retinal capillary blood flow in branch retinal vein occlusion areas and corresponding ipsilateral nonbranch retinal vein occlusion areas, 11 equivalent areas of the contralateral fellow eye of 12 consecutive untreated branch retinal vein occlusion patients, and 16 eyes of 11 age-matched normal control subjects were measured with scanning laser Doppler flowmetry. A template consisting of eight squares, each with a field of 100 x 100 µm (10 x 10 pixel) with space interval of 500 µm equidistant horizontally and vertically was used to obtain blood flow measurements in all subjects. Mean blood volume, flow, and velocity were obtained by averaging the mean values measured in each field. We avoided measurement over large retinal vessels to prevent the aliasing artifact of blood cells from moving faster than the sampling frequency.

Results:
Branch retinal vein occlusion areas have significantly decreased microvascular blood volume (P = .0009), flow (P = .02), and velocity (P = .016) compared with ipsilateral nonbranch retinal vein occlusion areas in the same eye. Branch retinal vein occlusion areas also have decreased blood volume (P = .001), flow (P = .0042), and velocity (P = .0044) compared with areas of contralateral fellow eyes of branch retinal vein occlusion subjects. Branch retinal vein occlusion areas have significantly decreased blood volume (P = .0012), flow (P = .008), and velocity (P = .02) compared with age-matched normal areas.

Conclusion:
Average retinal blood volume, flow, and velocity in areas of branch retinal vein occlusion are significantly lower than in healthy retinas. The ability to noninvasively measure hemodynamic changes in the retinal capillary bed may be relevant to development of new therapies for retinovascular disease.

Dialogue
No questions or comments have been posted

Responding Author:
William R. Freeman, MD
La Jolla, CA, USA


The effect of silicone ocular surgical devices on serum IgG binding to silicones

Dialogue
Authors: Saad Shaikh, MD, Lawrence S. Morse, MD, PhD, Randall M. Goldblum, MD, Jeffrey D. Benner, MD, Hal Burnett, MD, and Jeffrey Caspar, MD

Purpose:
To determine whether silicone materials used in retinal detachment repair and cataract surgery increase serum IgG binding to silicone and identify correlations with complications of ocular surgery.

Methods:
Serum from 49 patients who had ocular surgery using silicone materials was examined. Patient groups included scleral buckling (n = 25), silicone oil tamponade (n = 3), scleral buckling and silicone oil tamponade (n = 9), and silicone lens implants after cataract extraction (n = 12). Convalescent samples for all patients and preoperative samples from 19 patients (18 scleral buckling and one silicone oil tamponade) were examined. Postoperative complications were monitored for up to 108 months (mean, 10.7 months; mode, 1.5 months; range, 1 to 108 months). Samples were evaluated for the extent of IgG binding to silicones using a micromodification of a previously described enzyme-linked immunosorbent assay method.

Results:
In 19 patients, IgG binding levels in preoperative samples were 21 arbitrary units (AU) or less. Of the 25 buckling patients, one developed complications; however, in all patients the postoperative levels of IgG binding to silicone were low (2.2 to 20.0 AU). Although four silicone lens patients developed mild complications, none displayed postoperative IgG binding levels of greater than 20 AU. Three patients who underwent both scleral buckling and silicone oil tamponade developed complications; one of these patients, who was also noted to have systemic connective tissue disease, had a significant elevation in postoperative serum IgG binding to silicone.

Conclusion:
it must be a rare event that should not alter the clinical use of these important devices.

Dialogue
No questions or comments have been posted

Responding Author:
Lawrence S. Morse, MD, PhD
Sacramento, CA

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