Evaluation of laser sclerostomy fistulas using ultrasound biomicroscopy

Laser sclerostomy is a relatively new technique in glaucoma surgery. Clinical examination, particularly of the intrascleral part of laser sclerostomy fistulas, is difficult. We performed ultrasound biomicroscopy (UBM) in order to determine, if it were possible to visualize fistulas. Moreover, it was the aim to investigate whether this imaging technique could provide additional information on fistula morphology.

Ten eyes of eight patients with chronic open angle glaucoma who had undergone erbium-YAG laser sclerostomy ab externo were examined using a UBM-probe with a 20 MHz transducer providing spatial resolution of approximately 80 microm.

Radial scanning allowed visualization of the sclerostomy fistula in nine of ten eyes. The different functional state of sclerostomy fistulas correlated well to UBM findings. It was possible to image differences in the morphology of occluded and patent fistulas and to visualize the filtering pathway in functioning blebs.

Ultrasound biomicroscopy allows imaging of laser sclerostomy fistulas. UBM and clinical findings correlated well in the majority of the patients we examined. The technique supplements clinical examination and in some cases may provide additional information.