Retinal specific measurement of dark-adapted visual function: validation of a modified microperimeter

Area of Science:

• Ophthalmology
• Retinal imaging
• Visual psychophysics

Background:

• Scotopic function is a key indicator for retinal diseases and clinical trials.
• Traditional Humphrey Field Analyzer (HFA) lacks fixation control for scotopic testing.
• Microperimetry offers potential for precise scotopic visual function assessment.

Purpose of the Study:

• To evaluate a modified microperimeter for measuring scotopic visual function.
• To compare the modified microperimeter with a modified HFA for scotopic assessment.
• To assess the utility of microperimetry in identifying scotopic deficits.

Main Methods:

• A Nidek MP-1 microperimeter was modified with neutral density and shortpass filters.
• Fine matrix mapping perimetry was conducted on healthy subjects under scotopic conditions.
• Testing was performed using both the modified MP-1 and a modified HFA.

Main Results:

• Both instruments detected a foveal scotopic scotoma with >1 log unit sensitivity reduction.
• The MP-1 system precisely located the scotoma on the retina.
• Mean test time was shorter with the MP-1 (25 min) compared to the HFA (32 min).

Conclusions:

• A modified MP-1 microperimeter is suitable for measuring scotopic retinal function.
• The MP-1 offers comparable results to the HFA with added benefits of retinal tracking and localization.
• The modified MP-1 provides a faster and more precise method for scotopic assessment.