Accommodation power determined with visual evoked cortical potentials in psychogenic visual disturbances

Area of Science:

• Ophthalmology
• Neuroscience
• Psychiatry

Background:

• Accommodation failure can be subjective or organic.
• Psychogenic visual disturbances present diagnostic challenges.
• Accurate assessment of accommodation is crucial for diagnosis.

Purpose of the Study:

• To objectively measure accommodation power using visual evoked cortical potentials (VECP).
• To compare VECP-measured accommodation with subjective near-point rule measurements.
• To investigate the utility of VECP in diagnosing psychogenic accommodation disorders.

Main Methods:

• Pattern visual evoked potentials were recorded in 12 normal subjects and 3 patients with psychogenic visual disturbances.
• Steady-state visual evoked cortical potentials were measured while increasing minus-power lens.
• Objective accommodation power was determined by extrapolating the VECP amplitude vs. accommodation stimulus regression line to zero amplitude.

Main Results:

• In normal subjects, VECP-measured accommodation was approximately 2 diopters higher than subjective near-point rule measurements.
• Patients with psychogenic visual disturbances reported low subjective accommodation power but exhibited normal objective accommodation by VECP.
• VECP measurements provided objective data that contrasted with subjective patient reports.

Conclusions:

• The findings suggest that accommodation decrease in patients with psychogenic visual disturbances is due to psychogenic mechanisms.
• Visual evoked cortical potential measurement of accommodation is a reliable objective method.
• VECP can aid in differentiating psychogenic visual disturbances from organic causes of accommodation failure.