A Comparison of different scoring terminations rules for visual acuity testing: from a computer simulation to a...

Area of Science:

• Ophthalmology
• Optometry
• Vision Science

Background:

• Accurate visual acuity (VA) measurement is crucial for diagnosing and monitoring eye conditions.
• Standardized termination rules for VA testing are essential for reliable and reproducible results.
• Existing VA scoring methods may exhibit variability, impacting clinical decision-making.

Purpose of the Study:

• To compare the accuracy and test-retest variability (TRV) of four distinct visual acuity scoring termination rules.
• To evaluate the performance of 100%, one-miss, 50%, and per-letter termination rules using both simulation and clinical data.

Main Methods:

• A computer simulation involving 30,000 virtual patients and 2.4 million total tests on Snellen and ETDRS charts.
• Four termination rules were simulated: 100% correct, one miss, 50% correct, and a per-letter proportional scoring method.
• A clinical study with 254 subjects performing three repetitions of the ETDRS VA test to assess reproducibility.

Main Results:

• Simulation data indicated varying accuracy across rules, with per-letter showing high accuracy in ETDRS simulations.
• The per-letter rule demonstrated the lowest test-retest variability (TRV) in ETDRS simulations but had the longest test duration.
• Clinical study results showed the 50% and per-letter rules had significantly lower TRV (0.17 and 0.14, respectively) compared to 100% and one-miss (0.50 and 0.53).

Conclusions:

• Both simulation and clinical data support that the 50% and per-letter termination rules offer superior test-retest reliability.
• The 100% and one-miss rules exhibited higher test-retest variability, suggesting they may be less precise for VA scoring.
• The 50% and per-letter rules provide tighter and more consistent visual acuity measurements, enhancing diagnostic and monitoring capabilities.