Perimeetria

Perimeetria, commonly referred to as perimetry, is a diagnostic technique used to assess the visual field by determining the sensitivity to light stimuli at various locations within the field of vision. The resulting data produce a map of functional vision, highlighting areas of reduced or lost sensitivity that may indicate ocular or neurological disease. Perimeetria plays a central role in glaucoma management, where characteristic patterns of scotomas and overall field loss inform diagnosis and treatment decisions, but it is also used in evaluating optic neuropathies, retinal diseases, and brain injuries.

There are two main modalities. Static perimetry tests thresholds at fixed locations across the field to create a sensitivity map, while kinetic perimetry uses moving stimuli to delineate the borders of a patient’s visual field. Instruments range from automated static perimeters, such as commonly used Humphrey or Zeiss Octopus devices, to manual kinetic perimeters like the Goldmann perimeter. The procedure typically requires stable fixation, accommodation to a fixation point, and patient responses indicating stimulus detection. Test strategies aim to balance accuracy with efficiency and may include practice trials to reduce learning effects.

Results are presented as a visual field plot with global indices and regional patterns. Key outputs include mean deviation, pattern standard deviation, and total deviation values, along with isopters that define regions of equal sensitivity. Interpreting findings involves comparing with age-adjusted normative data and considering potential artifacts from fixation instability, media opacities, or patient noncompliance.

Historically, perimetry evolved from manual methods to automated systems beginning in the mid-20th century, enhancing standardization and reproducibility. Today, it remains a fundamental tool for diagnosing and monitoring conditions that affect the visual field.