Fig. 1 It is desirable to master more than one gonioscopic instrument to diagnose and treat the anterior chamber angle accurately. One gonioscopic device is insufficient to diagnose and treat eye diseases related to the anterior chamber angle. This figure demonstrates several instruments used in the office. For example, the Zeiss or comparable lens, number 2, (Table 1, II), is best for obtaining a rapid painless view of the angle and is especially helpful for evaluating eyes with narrow angles; lens number 5 (Magna View lens, Ocular Instruments, Bellevue, WA) allows a magnified view of the angle greater than a Goldmann for trabeculoplasty (magnification 0.93 versus 1.3); the classic Goldmann lens, number 1, is excellent for residents learning gonioscopy because the lens allows a large 140-degree field of view and stabilizes the globe better than a Zeiss-type lens. Because of anatomic variation of the width of palpebral fissures, the construction and size of the contact diameter of the Goldmann lens varies from 13 to 18 mm. The smaller lenses have one or two mirrors. The authors typically use the following gonioscopy lenses: a Zeiss or equivalent lens, Goldmann lens (13 mm, 15 mm, 18 mm) and Magnaview lens (trabeculoplasty) in the clinic and a Koeppe (magnified view), Barkan (goniotomy), and Posner (able to autoclave) in the operating room. This totals eight different gonioscopy devices to perform the specific functions necessary to examine and treat the chamber angle on a daily basis.