Humphrey visual field analyser

Device used for measuring visual fields in ophthalmology

The Humphrey visual field analyser is a sophisticated diagnostic tool used in ophthalmology to assess the visual field of a patient. It is widely utilized for detecting and monitoring glaucoma, as well as other conditions that affect the visual pathways.

Overview

The Humphrey visual field analyser is an automated perimeter that measures the entire area of peripheral vision that can be seen while the eye is focused on a central point. It is a critical instrument in the diagnosis and management of diseases that cause visual field loss.

Humphrey visual field analyser in use

Functionality

The device operates by projecting a series of light stimuli at various locations within the visual field. The patient is required to press a button each time they perceive a light stimulus. The results are then plotted to create a map of the visual field, highlighting areas of reduced sensitivity.

Test Procedures

The Humphrey visual field analyser offers several testing protocols, including:

• Central 24-2 and 30-2 tests: These are standard tests for assessing the central visual field, commonly used in glaucoma management.
• 10-2 test: This test focuses on the central 10 degrees of vision and is useful for detecting macular defects.
• Peripheral tests: These assess the outer regions of the visual field and are used for conditions affecting peripheral vision.

Trial lens used during visual field testing

Components

The main components of the Humphrey visual field analyser include:

• Stimulus projector: Projects light stimuli onto a dome where the patient focuses.
• Response button: Used by the patient to indicate when they see a stimulus.
• Trial lens holder: Holds corrective lenses to compensate for refractive errors during testing.

Interpretation of Results

The results from the Humphrey visual field analyser are presented as a series of plots that indicate the sensitivity of different areas of the visual field. These plots are crucial for identifying patterns of visual field loss.

Visual field plots showing areas of sensitivity

Common Patterns

• Arcuate scotoma: A common pattern in glaucoma, characterized by an arc-shaped area of vision loss.
• Nasal step: A step-like defect at the nasal field, often seen in early glaucoma.
• Altitudinal defect: Loss of vision in the upper or lower half of the visual field, which can indicate optic nerve damage.

Example of visual field loss

Artifacts and Errors

Artifacts can occur during testing due to patient movement, poor fixation, or incorrect lens use. It is important to distinguish these from true visual field defects.

Examples of artifacts in visual field testing

Clinical Applications

The Humphrey visual field analyser is primarily used in the diagnosis and monitoring of glaucoma. It is also valuable in assessing other conditions such as optic neuritis, retinal detachment, and stroke-related visual field defects.

Related Pages

• Glaucoma
• Visual field
• Perimetry
• Optic nerve