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

Abstract

ABSTRACT.Purpose: To estimate the repeatability of refractive error measurement (REM) in a clinical environment in cataractous, pseudophakic and healthy eyes. Methods: The refractive error of patients referred for cataract surgery or consultation measured by ophthalmic professionals was re-examined and the measurement results were compared. A total of 99 eyes from 99 persons (41 cataractous, 36 pseudophakic and 22 healthy eyes) with visual acuity (VA) of 0.3-1.3 (logMAR 0.52 to ) 0.11) were included. The differences between measurements 1 and 2 were calculated as 3-dimensional vector values and spherical equivalents (SEs) and expressed as the coefficient of repeatability (CR). The mean time interval between the first and second examinations was 45 days. Results: The CRs for all eyes for vertical (V), torsional (T) and horizontal (H) vectors were 0.74 D, 0.34 D and 0.93 D, respectively. The CR of SE for all eyes was 0.74 D. Eyes with lower VA (0.3-0.45) had larger variability in vector and SE values but the differences between VA groups were not statistically significant. The difference in the mean defocus equivalent (DE) between measurements 1 and 2 was, however, significantly greater in the group with lower VA. In all VA groups the mean difference vector was very close to the zero vector, which means that there was no systematic difference. Conclusions: Repeatability of refractive error measurements in clinical settings has a certain degree of variability. In this series, the variability in eyes with better VA was not great and was in accordance with earlier findings in healthy eyes. Eyes with lower VA had greater variability due to greater tolerance to defocus. Thus, conclusions concerning changes in the refractive state and the need to make changes in the refractive correction of eyes with poorer vision should be made with caution.

An Analysis of the Factors Influencing the Residual Refractive Astigmatism After Cataract Surgery With Toric Intraocular Lenses

“…Only patients with high best-corrected visual acuity were enrolled, which makes refraction assessment repeatable. 19 To evaluate the outcome in astigmatism, we developed a number of optical equations based on the Naeser polar value concept.…”

Refractive Predictability of Partial Coherence Interferometry and Factors that can Affect It

“…These may include differences in capsulorhexis configuration, the actual postoperative ACD (positioning of the IOL) of individual eyes, differences in wound healing processes, variability of the time interval required to reach refractive stability, and errors related to the measurement of postoperative refraction. However, it seems that some of these factors are not measurable and thus are not controllable; it has also been suggested that some are inevitable 31,36. Despite these limitations, we hope that our study will provide valuable guidance in the interpretation and application of biometric data obtained by the IOL Master® in current clinical settings.…”

Sources of error in intraocular lens power calculation

“…The SD of manual refraction was estimated to be one quarter of the 95% limits of agreement, or 0.39 D, as determined by Bullimore et al 15 This is of the same order of magnitude as in a recent study by Leinonen et al, 26 who found 0.37 D, again estimated as one quarter of the 95% limits in a mixed group (n Z 99) of healthy, pseudophakic, and cataractous patients. In patients with a visual acuity of 0.7 or better (z20/30) they found 0.25 D, but the difference was not statistically significant.…”