Dreidimensionale Darstellung von Sklerotomien mittels Ultraschallbiomikroskopie

BACKGROUND When pars plana vitrectomy is performed, the sizes of the sclerotomy cannula vary between 20 and 23 gauge. We examined the morphology of the scleral tunnels by ultrasound biomicroscopy additionally taking into account the incision angle. MATERIAL AND METHODS In each of 16 enucleated porcine eyes three 20 or 23 gauge sclerotomies with varying angles between 30 and 90° to the horizontal level were performed. The vertical 20 gauge sclerotomies were additionally sealed by 7.0 vicryl cross-stitching. The resulting scleral channels were analysed by 3-D ultrasound biomicroscopy. RESULTS The sclerotomies were echographically detectable in all cases. Analysis revealed that the sutured straight 20 gauge tunnels were hyporeflective in only some parts while the other incisions showed continuous hyporeflectivity along the complete channel in many cases. The smaller the instruments used and the flatter the scleral angles chosen, the smaller were the measured widths of the incision tunnels. CONCLUSION Imaging sclerotomies ex vivo by ultrasound biomicroscopy is reliably reproducible. In the echographic pictures straight 20 gauge incisions appeared to be safely sealed by the sutures while the nonsealed tunnels often showed continuous patency. By choosing small instruments and flat incision angles the width of the resulting scleral channels can be reduced.