| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Background : Postoperative peripheral visual field loss is well recognized as a complication following vitrectomy. Clinical findings of nerve fiber layer loss, focal arteriolar narrowing, and segmental optic disc paper in the region of retina corresponding to the visual field defect have been reported. However, the etiology of this complication remains unclear. The purpose of this study was to (1) establish the in situ visualization of affected region by airlfluid exchange (AIF) procedure, (2) evaluate the effects of A/F procedure on the retina by this technique as well as immunohistochemistry and electron microscopy, and (3) consider the surgical technique to prevent this complication.
Methods : 0.2cc of C3F8 gas was injected into one eye of adult pigmented rabbits and the same eye was subjected to lensectomy, vitrectomy, induction of PVC and A/F procedure 30 days later. A/F was performed using room air at 50 mmHg infusion pressure for various time durations(1,3,5,10min). In controls,
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the same procedures except A/F were done. After the procedures, 0.4% trypan blue solution was injected into the vitreous cavity followed by a wash with saline and the dye inclusion was observed under operating microscope. Eyes were then enucleated and processed for immunohistochemistry and electron microscopic analysis. The relationship between these results using rabbit eyes and clinical characteristics was analized.
Results : A/F treatment for 1, 3, 5, and 10 min all induced clearly demarcated trypan blue staining on the surface of the retina in the region opposite to the infusion cannula, while staining intensity increased as the infusion time increased. No trypan blue inclusion was detected in controls. Electron microscopy of trypan blue stained region revealed defects in the inner limiting membrane, nerve fiber and ganglion cell layers and the inner portion of Muller cells. The severity of these changes was more remarkable in the retinae which received longer A/F treatment. In the trypan blue positive region, a siginificant increase in the GFAP expression in Muller cells was also noted by GFAP immunostaining. The characteristics of most of the cases who had this complication related to the high pressure and longer duration during A/F, and histological examination of removed tissue from damaged retina in one case showed damaged the inner limiting membrane attached ganglion cells and nerve fibers.
Conclusions : These results clearly indicate that (1)A/F procedure causes mechanical damages to the inner retinal region and (2) the trypan blue inclusion test is a convenient method to evaluate the tissue damage and could be clinically applicable. (3) the decrease of the pressure and period during A/F is very important to prevent this complication. Less
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