Heidelberg Edge Perimeter: The New Method of Perimetry.

Glaucoma is an optic nerve neuropathy associated with progressive visual field loss. One of the most frequent eye diseases these days, it is believed to have affected 60 million people worldwide in 2014. Various visual field examination methods are known, from the confrontational test to kinetic and static perimetry. The latest device to access the visual field is the Heidelberg Edge Perimeter (HEP). It is a flicker perimeter, but, unlike others of its kind, it uses a unique stimulus called FDF (Flicker Defined Form). A 5-grade round stimulus is created by reversing the phase of flickering black and white dots, thereby forming illusory outlines. The test uses randomly flickering points in medium illumination (50 cd/m²). The background remains the same during the whole test. Background luminance is 50 cd/m2, the marker showing time is 400 ms, and the frequency is 15 Hz. Current studies show that HEP can detect early visual field loss which remains invisible during a standard visual field test with standard automated perimetry. HEP might also prove useful in the early detection of other diseases connected with visual field loss, for example in neurology.