Abstract : Forty-two eyes in which there were residual retinoblastomas following radiotherapy were examined histopathologically. Forty percent of the tumors showed areas of photoreceptor differentiation. Three histopathologic patterns were noted. Some tumor nodules consisted entirely of cells showing photoreceptor differentiation while other tumor nodules consisted of cells mingled with glial cells or undifferentiated retinoblastoma cells. Detailed clinical descriptions before and after radiation therapy were available on four of the tumor nodules. These tumor nodules were described as grayish, translucent, or 'fish flesh' in appearance. In the follow up of 13 patients, only 1 tumor death was recorded. This study suggests that, while the tumors with photoreceptor differentiation are relatively benign histopathologically, they are comparatively resistant to radiotherapy.
Abstract : Two grades (II and III) of retinal lesions were evaluated using clinical, histopathologic, and morphometric methods from 3 days up to 20 days after the laser insult. Morphometric parameters varied according to time and the energy of the laser used. Preliminary evaluation of the efficacy of high-dose, and continuous infusion of methylprednisolone was performed using a swivel- tethering system. Clinical study at 3 and 10 days after laser injury suggested a dramatic beneficial effect when the drug was given at 24 hours before injury and continued for 4 days. Preliminary histopathologic observation also suggested a protective effect of the treatment regimen. Morphometric analysis is underway. In addition, two human cases of laser injury to the retina were studied clinically as a basis for clinical application of therapeutic modalities. Laser; Retina; Injury; Treatment; Corticosteroids; Methylprednisolone; RA 3
Abstract : Efficacies of three different regimens of high dose of methylprednisolone (MP) treatment on laser-induced non-hemorrhage retinal injury and tissue plasminogen activator (t-PA) in sub-retinal hemorrhage laser injury were evaluated in a sub-human primate model and a rat model respectively. Clinical, histopathological, and morphometric criteria were employed for evaluating the efficacy of MP. High dose and prolonged treatment (4 days) was the most effective regimen while high dose for 8 hours showed limited effect in non-hemorrhagic retinal injury. Intravitreal t-PA showed no apparent beneficial effect in sub-retinal hemorrhage after laser injury. Hence, patients with laser retinal injury may benefit from high dose MP treatment for an appropriate period of time. Laser, Retina, Injury, Treatment, Corticosteroids, Methylprednisolone, tissue plasminogen activator, sub-retinal hemorrhage, RA 3.
• Rats with experimental diabetes (induced by streptozocin [Streptozotocin]) were studied by vitreous fluorophotometry and horseradish peroxidase tracer technique. Vitreous fluorescein sodium concentration notably increased four to eight days after a single dose of streptozocin. No leakage from the retinal vasculature could be demonstrated by the horseradish peroxidase tracer study, but three types of retinal pigment epithelial (RPE) lesions were observed. The RPE lesions seemed to be partially responsible for the increase of vitreous fluorescein concentration.
The morphologic effects on the retina resulting from chronic lead exposure were assessed in neonatal rats. Newborn rats nursed from dams were given a low (0.115%) or a high (4.5%) concentration of lead in their diet. At day 21 the pups were weaned to the mother's diet. The retinas of the pups were studied by electron microscopy at various ages up to day 60. High and low lead concentrations produced necrosis of photoreceptor cells and cells of the inner nuclear layer. The high lead concentration, in addition, was associated with swelling of endothelial cells of the retinal vessels and narrowing of the lumen. Increased permeability of the retinal vessels and pigment epithelium to horseradish peroxidase was also observed under the high-dose condition. The authors conclude that lead can produce direct neuronal damage and, at high doses, produces retinal vascular lesions and alteration of the blood-retinal barrier.
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