Volumetric Analysis of Perimetry Tests to Guide Central Testing: The Functional Vulnerability Zone

Area of Science:

• Ophthalmology
• Visual field testing
• Glaucoma diagnostics

Background:

• Glaucoma diagnosis and monitoring rely on visual field testing.
• Standard visual field tests may not fully capture residual visual sensitivity in early glaucoma.
• Identifying areas of remaining function is crucial for accurate progression assessment.

Purpose of the Study:

• To characterize the functional vulnerability zone (FVZ) in glaucoma using volumetric analysis of total deviation (TD) perimetric data.
• To assess residual sensitivity measurable by the 10-2 test grid compared to the 24-2 test grid.
• To develop a prototype application for clinical guidance in glaucoma management.

Main Methods:

• Volumetric analysis of TD perimetric data from Humphrey Field Analyzer 10-2 and 24-2 tests.
• Calculation of TD volume difference (10-2 minus 24-2) and number of test locations gained.
• Application of linear regression and principal components analysis to identify predictive features of FVZ.

Main Results:

• Visual field global indices and central 24-2 defects significantly predicted TD volume difference (P < 0.0001).
• 24-2 Mean Deviation (MD) showed the highest R² (0.32) for predicting TD volume difference.
• A simplified model using 24-2 MD and number of central 24-2 TD probability defects identified FVZ likelihood (P < 0.01).

Conclusions:

• The functional vulnerability zone (FVZ) provides a data-driven method to identify residual visual dynamic range using the 10-2 test grid.
• A prototype model is proposed for predicting the clinical utility of the 10-2 test in glaucoma progression analysis.
• This approach enhances the characterization of visual field defects in glaucoma.