Abstract
Purpose :
Myopia is the most common refractive error and is characterized by blurring of objects viewed at a distance when accommodation is relaxed. As cycloplegia in clinical settings depends on various factors (used pharmaceuticals, time course of application) and as the application of cycloplegia requires trained examiners and more time-consuming measurements under dry (non-cycloplegic conditions) are often preferred.
In order to investigate the agreement between the two measurement conditions, the deviation between wet subjective refraction (cSub) and dry objective wavefront aberrometry (ncOb) has been investigated in a controlled environment of an randomized clinical trial using myopic children.
Methods :
84 right eyes of myopic children (range of cSub spherical equivalent refractive error (SE) -0.75 D to -4.88 D) aged 6 to 13 years were analyzed. NcOb was determined using a wavefront-based autorefraction (i.Profiler plus, Carl Zeiss Vision GmbH, Aalen, Germany), and cSub was performed.
For analysis, obtained data were converted into SE, and Bland-Altman plots were used to analyze the agreement between both methods (ncOb - cSub).
Results :
The bias between the two methods can be described as a linear function to account for the influence of the amount of refractive error. The function is y=-0.29*0.071x, and accordingly, for the LOAs y=0.19*0.071x (upper limit) as well as y=-0.76*0.071x (lower limit), respectively. A graphical representation of the regressions and data is provided in Figure 1.
Conclusions :
The SE measured with ncOb showed a tendency towards more myopia compared to cSub. This finding is in agreement with published studies, especially in children. In order to perform a bias correction, it seems that the amount of refractive error needs to be considered since lower myopia tends to have a smaller bias than higher ones. This deviation becomes clinically relevant depending on the degree of refractive error.
The presented bias correction enables a clearer interpretation of refraction results between objective and subjective methods.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.