Zeiss Matrix Visual Field Analyzer (also known as the Humphrey Matrix)

The Humphrey Matrix represents the latest breakthrough in visual field
testing. It combines the capability to detect glaucoma early and accurately,
with tools for long-term management.

Frequency doubling technology isolates a subset of retinal ganglion cells
in the magnocellular (M-cell) pathway. Patterns of flickering black and
white bars trigger a reaction in these cells, creating an illusion that
twice the number of bars are actually present, hence "frequency doubling."
Retinal ganglion cells are sparsely populated so there is less redundancy
to mask any cell damage. By isolating these cells, Humphrey Matrix
detects glaucomatous damage early in the disease process.

The Humphrey Matrix threshold tests present a stimulus to different locations throughout the central 30° radius of the visual field. If the patient detects a target, its contrast is reduced for the next presentation at that location; the contrast is increased when a stimulus is not detected. This process continues until thresholds for stimulus detection are determined. The results are presented in terms of dB for contrast sensitivity at each location tested.