Shaffer System
A more commonly used grading system is that of Shaffer (1960, 1962). This system describes the degree to which the angle is open rather than the degree to which it is closed. Whereas Scheie’s grade IV denotes a closed angle, on the Shaffer scale grade 4 refers to a wide-open angle. The Shaffer system approximates the angle at which the iris inserts relative to the trabecular meshwork (6‑3). If the angle between the iris and the meshwork is 20° to 45°, the angle is felt to be at no risk of closure. Angles from 0° to 20° are considered capable of closure (Table 1).
Many ophthalmologists use a variation of Shaffer’s system in which 4 is wide open and 0 is closed, but the determination is usually a rough estimate of angle width that is not strictly based on degrees.
6-3 Shaffer’s grading system is based on the angle between the iris and the trabecular meshwork. For angles of 20ยบ or less angle closure is possible. (Reprinted with permission from Trans Am Acad Ophthalmol Otolaryngol [1960;64:112– 127]. Shaffer RN. Primary glaucomas. Gonioscopy, ophthalmoscopy and perimetry.)
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