Repeatability (test-retest variability) of refractive error measurement in clinical settings

Area of Science:

• Ophthalmology
• Optometry
• Clinical Measurement Science

Background:

• Accurate refractive error measurement (REM) is crucial for visual correction.
• Understanding the repeatability of REM in various ocular conditions is essential for clinical decision-making.

Purpose of the Study:

• To assess the repeatability of refractive error measurement (REM) in clinical settings.
• To compare REM repeatability across cataractous, pseudophakic, and healthy eyes.

Main Methods:

• Re-examined refractive error in 99 eyes (cataractous, pseudophakic, healthy) by ophthalmic professionals.
• Calculated coefficient of repeatability (CR) for 3-dimensional vector values and spherical equivalents (SEs).
• Analyzed repeatability based on visual acuity (VA) and time interval (mean 45 days).

Main Results:

• Overall CR for vertical, torsional, and horizontal vectors were 0.74 D, 0.34 D, and 0.93 D, respectively.
• The CR for SE was 0.74 D across all eyes.
• Eyes with lower VA exhibited greater variability in vector and SE, though not statistically significant.

Conclusions:

• Repeatability of clinical REM exhibits variability, particularly in eyes with lower visual acuity.
• Variability in eyes with better VA aligns with previous findings in healthy eyes.
• Greater variability in poorer vision eyes may stem from increased defocus tolerance; caution advised when interpreting refractive state changes.