Clinical Validation of an Afocal Optical System in Visual Acuity Testing

Area of Science:

• Ophthalmology
• Optical Engineering

Background:

• Visual acuity (VA) measurement is crucial in ophthalmology.
• Conventional methods like Snellen and ETDRS charts have limitations in precision.
• An afocal optical system offers potential for improved VA testing accuracy.

Purpose of the Study:

• To validate the feasibility of an afocal optical system for visual acuity measurement.
• To compare the performance of the Afocal Visual Acuity Test (AVAT) device with traditional charts.
• To assess the reliability and accuracy of the AVAT device.

Main Methods:

• An afocal optical system was integrated into the AVAT device.
• Perceived optotype sizes were compared across AVAT, Snellen, and ETDRS charts at varied distances.
• A prospective study involving 58 participants was conducted at a national university hospital.

Main Results:

• The AVAT device demonstrated lower variability in perceived optotype sizes compared to Snellen and ETDRS charts.
• AVAT showed strong correlations with ETDRS (r=0.904) and Snellen (r=0.906) charts.
• Receiver operating characteristic analysis indicated high diagnostic performance for AVAT (AUC=0.975).

Conclusions:

• The AVAT device, utilizing an afocal optical system, correlates well with conventional visual acuity tests.
• The AVAT device shows promise as a feasible and accurate tool for visual acuity measurement.
• Further research with larger sample sizes is recommended to confirm test-retest reliability.