What is the oblique flashlight test?

It is a quick way to estimate the depth of the anterior chamber of the eye without use of a gonioscope.

A light is held parallel to the iris. If a shadow is cast, the angle is narrow. If there is no shadow, the angle is open.

Source

Mahadevan, S.V. and Garmel, G.  An Introduction to Clinical Emergency Medicine: Guide for Practitioners in the Emergency Department.