Effect of dichoptic adaptation on frequency-doubling perimetry

Area of Science:

• Ophthalmology
• Visual Neuroscience
• Perimetry

Background:

• Frequency-doubling technology (FDT) perimetry is a clinical visual field test.
• A known phenomenon is reduced sensitivity in the second eye during FDT perimetry.
• The underlying cause of this sensitivity reduction requires investigation.

Purpose of the Study:

• To investigate the cause of reduced sensitivity in the second eye during FDT perimetry.
• To differentiate between adaptation, fatigue, and occlusion effects.

Main Methods:

• Contrast sensitivity was measured using frequency-doubling (0.25 cpd, 25 Hz) and non-flickering (4 cpd) gratings.
• Different testing orders and occlusion methods (opaque vs. translucent) were employed.
• Measurements were taken with varying inter-eye testing intervals and occlusion durations.

Main Results:

• A significant reduction in frequency-doubling sensitivity (0.15 log) was observed in the second eye tested.
• This reduction persisted even with orthogonally oriented gratings, ruling out dichoptic contrast adaptation.
• Minimal sensitivity changes occurred after testing with non-flickering gratings, indicating small fatigue effects.
• Sensitivity decreased after 5 minutes of opaque occlusion, but a translucent occluder prevented this reduction.

Conclusions:

• Reduced sensitivity in the second eye during FDT perimetry is confirmed.
• The primary cause is delayed light adaptation occurring after eye occlusion.
• The use of translucent occluders can mitigate this sensitivity loss.