Abstract
Introduction: There is evidence that certain measures of visual function show some type of relationship between right and left eyes in the same individual. Similarly, particular ocular maladies may be related, or be symmetric, in the right and left eyes of the same person. There is also evidence to suggest that certain relationships do not exist between eyes in an individual. For example, diseases such as glaucoma are often asymmetric in their progression in the two eyes of an afflicted individual. Inter-ocular mirror symmetry between right and left eyes, when considering ocular wave-front aberrations (WAs), has been shown to exist by some authors. This study investigates whether mirror symmetry of high order aberrations (HOAs) exists between the right and left eyes in a cohort of South African subjects. Method: Third to 5th order Zernike coefficients (HOAs) were measured on both eyes of 66 subjects (132 eyes) using a Zywave aberrometer. A total of 15 Zernike coefficients for each eye were obtained. Mirror symmetry was investigated using correlation coefficients between the various measurements obtained from each eye. Results: Pearson product-moment correlation coefficients provide evidence that the majority of the 15 Zernike coefficients suggest the presence of mirror symmetry between right and left eyes of the 66 subjects. Examples of individual scatter plots comparing right and left eyes are presented. Conclusion: The results of this study suggest that mirror symmetry exists in the HOAs obtained from the 132 eyes measured and thus care should be exercised when combining eyes of individuals for analysis. (S Afr Optom 2013 73(1) 39-44)
Highlights
There is evidence that certain measures of visual function show some type of relationship between right and left eyes in the same individual
Whether a correlation coefficient was found to be significant or contribute to the existence of possible symmetry is included in Table 1
The calculated correlation coefficients between the right and left eyes indicate that most of the 15 Zernike coefficients in the right and left eyes contribute to mirror symmetry
Summary
There is evidence that certain measures of visual function show some type of relationship between right and left eyes in the same individual. There is evidence to suggest that certain relationships do not exist between eyes in an individual. This study investigates whether mirror symmetry of high order aberrations (HOAs) exists between the right and left eyes in a cohort of South African subjects. When analysing measurements obtained from both eyes of an individual one needs to take the correlation that often exists between the two eyes into account, because the right and left eyes of individuals are more likely to be similar to each other than measurements obtained from an unrelated person[1]. Smolek et al[4] have expressed concern that not accounting for the existence of mirror symmetry between right and left eyes can invalidate results of studies investigating aberrations. To allow for the possible existence of mirror symmetry between right and left eyes one may either use only right or only left eyes for a study, or right and left eyes are analysed separately or one may adjust the signs of some of the Zernike coefficients for one of the eyes investigated, usually the left eye[2]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call