Stage 1

Closed angle

0˚

No visible structure

Stage 2

Probable closure

0˚ - 10˚

Visible Schwalbe ring

Stage 3

Possible closure

10˚ - 20˚

Scleral spur not visible

Stage 4

Unable to close

20˚ - 35˚

Clearly visible spur

Stage 5

Open

35˚ - 45˚

All structures are clearly

visible up to the ciliary band