Ocular's Maxfield AC 4 Mirror Gonio Lens features high refractive index glass, providing total internal reflection even with fluid in contact with the mirrors. Total internal reflection means no light absorbtion or loss by a mirror coating, resulting in a brighter, clearer image. Ocular's MaxFiled AC Four Mirror Gonio Lens provides high resolution image of the anterior chamber angle. The only all glass steam sterilizable gonio scope available. Patent Pending. Also available with large holding ring (O4MAC-LR).