Gonioscopy Grading: Shaffer, Scheie and Spaeth Systems
Last updated: October 2026
Short answer: gonioscopy grading describes how open the anterior chamber angle is. The Shaffer system grades the angle width from 0 (closed) to 4 (wide open); the Scheie system grades by visible structures, in the opposite direction; and the Spaeth system records iris insertion, angle width and iris shape. Use dynamic (indentation) gonioscopy to tell appositional from synechial closure.
Know the structures (from the iris root upwards)
- Ciliary body band
- Scleral spur
- Trabecular meshwork (posterior pigmented part filters most aqueous)
- Schwalbe's line
Shaffer grading
| Grade | Approximate angle width | Deepest structure seen | Risk of closure |
|---|---|---|---|
| 4 | 35–45° | Ciliary body | Closure impossible |
| 3 | 20–35° | Scleral spur | Closure impossible |
| 2 | About 20° | Trabecular meshwork | Closure possible |
| 1 | About 10° | Schwalbe's line only | Closure probable |
| Slit | <10° | No clear structures | Closure very likely |
| 0 | 0° | None (iris against cornea) | Closed |
Scheie grading (reversed direction)
Scheie grades by how much of the angle is hidden: wide open (all structures visible), then grades I (iris root hard to see), II (ciliary body not visible), III (posterior trabecular meshwork hidden) and IV (no angle structures visible). A higher Scheie grade means a narrower angle, the opposite of Shaffer. Always write which system you used.
Spaeth grading
- Iris insertion: A (anterior to Schwalbe's line), B (behind Schwalbe's line), C (at the scleral spur), D (deep, ciliary body visible), E (extremely deep).
- Angle width in degrees (for example, 10°, 20°, 30°, 40°).
- Peripheral iris configuration: commonly described as flat, convex (bowed forward), concave, or plateau.
- Pigmentation of the posterior trabecular meshwork can be graded 0–4.
- Recording both the appearance without indentation and the position with indentation gives the most information.
Technique pearls
- Use a dark room and a very short, thin slit beam that does not shine through the pupil; light constricts the pupil and opens the angle artificially.
- Keep the lens still and avoid pressing on the cornea; inadvertent pressure distorts the angle and can make a narrow angle look more open than it really is.
- Dynamic (indentation) gonioscopy with a 4-mirror lens: if the angle opens on indentation, closure is appositional; if not, there are peripheral anterior synechiae (PAS).
- The corneal wedge (where the two slit reflections meet) locates Schwalbe's line in difficult angles.
- Look for PAS, neovascularisation of the angle, angle recession, and abnormal pigment (such as Sampaolesi's line in PXF).
Van Herick: a quick screening estimate
At the slit lamp, compare the peripheral anterior chamber depth with the corneal thickness: grade 4 (equal or deeper), 3 (¼ to ½), 2 (¼) and 1 (less than ¼). Grades 1–2 need gonioscopy. Van Herick is a screening tool; it does not replace gonioscopy.
Frequently asked questions
What is the difference between Shaffer and Scheie grading?
Shaffer grades angle width from 0 (closed) to 4 (wide open). Scheie grades by hidden structures, so a higher Scheie grade means a narrower angle. Always state which system you used.
What does indentation gonioscopy show?
It shows whether a closed angle can be opened. If it opens on indentation, closure is appositional; if it stays closed, there are peripheral anterior synechiae.
Why should gonioscopy be done in a dark room?
Light constricts the pupil, which pulls the peripheral iris away from the angle and makes it look more open than it really is.
Related: angle anatomy, angle closure and target IOP.
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