Van Herick Test

The Van Herick test is a slit lamp estimation of the angle depth. It was developed when gonioscopy was performed with the Koeppe lens and was inconvenient and time-consuming. It should not be used as a replacement for gonioscopy but can be used as a means of confirming or refuting what the gonioscopy examination shows. In nonpigmented angles it can be difficult to determine whether the angle is open or closed. The corneal wedge can help but sometimes the wedge is difficult to identify. The Van Herick test will help to estimate the angle width.

To perform the Van Herick test the slit beam is made very bright and thin. It is offset 60° temporally to the slit lamp oculars. The temporal sclera is illuminated and the slit lamp beam is brought slowly towards the cornea until the anterior chamber is first identified. The thickness of the cornea is compared to the depth of the peripheral anterior chamber. If the anterior chamber depth is as deep as the cornea is thick then the angle is presumed to be wide open. If there is only a slit of aqueous then the angle is estimated to be dangerously narrow (See Table below video player).

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Van Herick Angle Depth Estimation

Chamber Depth In Corneal Thicknesses	Angle Grade
≥ Cornea	4
¼ to ½	3
¼	2
<1/4	1
Slit	Dangerously narrow

From: Van Herick W, Shaffer RN, Schwartz A. Estimation of width of angle of anterior chamber. Incidence and significance of the narrow angle. Am. J. Ophthalmol. 1969;68:626-629.