Abstract
Abstract: :
Purpose:Macular edema is one of the most serious adverse effects following retinal scatter laser photocoagulation. While it has been suggested that the changes of the retinal blood flow distribution or the inflammatory reaction following photocoagulation may be involved in the pathogenesis of macular edema, little information is available about its exact mechanism. This study was designed to evaluate quantitatively leukocyte-endothelial cell interactions and vascular permeability in the uncoagulated portions of the retina after partial scatter laser photocoagulation. Methods:Argon laser photocoagulation was performed to one half of the retina in male pigmented rats (n=90). In the other half of the retina, leukocyte dynamics after photocoagulation were evaluated in vivo with acridine orange digital fluorography. Retinal vessel permeability was quantified by using Evans blue dye. Results:Scatter laser photocoagulation caused significant inflammatory leukocyte-endothelial interactions in not only the photocoagulated but also the untreated half of the retina. In the unphotocoagulated half of the retina, the number of leukocytes rolling along the major retinal veins increased after photocoagulation and peaked at 12 hours (14.3 ± 4.5 cells/minute/vessel). Leukocyte accumulation in the untreated half of the retina increased after photocoagulation with a peak of 47.5 ± 13.0 cells/mm2 24 hours after photocoagulation. Retinal vascular permeability in the untreated half of the retina gradually increased after photocoagulation. Conclusion:Scatter laser photocoagulation increased leukocyte rolling and subsequent accumulation in not only the photocoagulated portion but also the untreated portion of the retina. The accumulated leukocytes would be involved in the augmented vascular permeability in the untreated retina, resulting in retinal edema after photocoagulation.
Keywords: 454 laser • 437 inflammation