The cloudy cornea in primary infantile glaucoma may contraindicate a goniotomy if a view of the anterior chamber angle is not obtainable through the operating microscope. The purpose of this study was to determine if a gradient-index (GRIN) endoscope was capable of improving the imaging of the anterior chamber angle structures in vitro. The anterior chambers of cadaver porcine eyes were deepened with a viscoelastic material. The GRIN lens endoscope entered the anterior chamber through a corneal incision near the limbus. The anterior chamber structures including the pectinate ligaments in the angle were clearly visualized on a video screen as the endoscope was advanced into the anterior chamber angle. The amount of illumination was automatically controlled. A low OH silica fiber having a core diameter of 100 microns and delivering 10 mJ of Holmium:YAG energy was inserted into the endoscope. Due to the low amount of energy, the pectinate ligaments were inconsistently cut. The specimens were examined with a dissecting microscope, fixed in formalin, and processed for light microscopy. A thin endoscope allows intraoperative examination of anterior segment structures when a cloudy cornea is present. Therefore, it may become a useful instrument for performing a goniotomy in primary infantile glaucoma when direct visualization of the anterior chamber angle is not possible with a goniotomy lens.