Minimizing Pupil Size Dependence in Flicker ERG Using Stiles-Crawford Compensation

Area of Science:

• Ophthalmology
• Visual Neuroscience
• Medical Imaging

Background:

• The Stiles-Crawford effect (SCE) influences retinal illuminance based on pupil size.
• Electroretinograms (ERGs) are crucial for diagnosing retinal disorders.
• Pupil size variations can affect ERG measurement reliability.

Purpose of the Study:

• To determine the impact of the Stiles-Crawford effect (SCE) on electroretinograms (ERGs).
• To evaluate the effectiveness of SCE compensation in improving ERG diagnostic reliability.
• To minimize the influence of pupil size variations on ERG measurements.

Main Methods:

• Flicker ERGs were recorded from 10 healthy subjects.
• Real-time retinal illuminance adjustment was performed using the RETeval system based on pupil size.
• Preset SCE compensation factors (ρdevice) of 0, 0.05, 0.085, and 0.12 mm⁻² were applied with Troland stimuli.

Main Results:

• Larger pupil areas prolonged implicit times with ρdevice = 0 and 0.05 mm⁻², while ρdevice = 0.12 mm⁻² reduced implicit time.
• Amplitudes were lower with ρdevice = 0 mm⁻² but increased with ρdevice = 0.085 and 0.12 mm⁻².
• Optimal ρdevice values to minimize pupil size dependence were 0.086 mm⁻² for implicit time and 0.05 mm⁻² for other measures, predicting ≤7% variability.

Conclusions:

• Using Troland stimuli with ρdevice = 0.05 mm⁻² minimizes pupil size impact on cone-mediated ERGs.
• Appropriate SCE coefficient application enhances ERG measurement reliability and diagnostic accuracy.
• This compensation strategy improves clinical ERG assessments despite pupil size variations.