Validation of Simplified Visual Acuity Testing Protocols in Amyotrophic Lateral Sclerosis

Area of Science:

• Ophthalmology
• Neurology
• Biomedical Engineering

Background:

• High- and low-contrast visual acuity (HCVA, LCVA) are potential quantitative markers for neurological dysfunction in amyotrophic lateral sclerosis (ALS).
• Current gold standard (GS) visual acuity (VA) protocols are complex and time-consuming, limiting their clinical application in neurology.

Purpose of the Study:

• To compare the validity of simplified visual acuity (VA) protocols against gold standard (GS) methods for measuring HCVA and LCVA.
• To assess the potential of simplified VA protocols as practical quantitative markers for neurological assessment in ALS.

Main Methods:

• Monocular HCVA and LCVA were measured in 10 ALS patients and 4 controls using six protocols.
• Protocols varied in chart type (e.g., LCD tablet) and refraction method (e.g., pinhole correction).
• Intraclass correlation coefficients (ICCs) were calculated to compare simplified protocols with GS methods.

Main Results:

• Simplified HCVA protocols demonstrated excellent agreement with GS methods (ICCs 0.83–0.98).
• Simplified LCVA protocols showed only moderate agreement with GS methods (ICCs 0.56–0.75), with differences exceeding test-retest reliability.
• Valid HCVA measurements were achieved using LCD tablet charts and/or pinhole correction; no modified LCVA protocols yielded valid measurements.

Conclusions:

• Simplified HCVA protocols, particularly those using LCD tablet charts and pinhole correction, are valid and potentially practical for clinical use in ALS.
• Current simplified LCVA testing protocols are not sufficiently reliable for use in ALS neurological assessment.
• Further refinement of LCVA protocols is needed to establish their utility as quantitative markers in neurological disease.