Morphology of the normal visual field in a population-based random sample: principal components analysis

Area of Science:

• Ophthalmology
• Vision Science
• Biostatistics

Background:

• Understanding normal visual field variability is crucial for detecting glaucomatous changes.
• Humphrey visual field testing is a standard diagnostic tool.

Purpose of the Study:

• To analyze the principal components of visual field threshold values in a normal population.
• To describe the primary pattern of visual field variation and its relationship to average threshold.

Main Methods:

• Principal components analysis (PCA) applied to Humphrey central 24-2 threshold data from 304 clinically normal individuals.
• Analysis of the first principal component and its corresponding eigenvector.

Main Results:

• The first principal component explained 62% of the variance in visual field data.
• This component represents the average threshold value across both eyes.
• The associated eigenvector visually maps to an 'umbrella' shape, showing visual field rise and flattening with increasing average threshold.

Conclusions:

• A dominant pattern of visual field variation exists, characterized by an 'umbrella' shape.
• This pattern is strongly linked to the average visual field sensitivity.
• Further investigation into the physiological basis of this observed variation is warranted.