Multivariate analysis of near additions for presbyopic patients at a rural optometry clinic

Background: Presbyopia is often overlooked in refractive error distribution analysis. This article employs multivariate analysis to address this gap, enhancing understanding of means, outliers and variations through graphical data presentation. Aim: To analyse the distribution of near-corrective optical additions for presbyopic patients over 2 years at a rural optometry clinic. Setting: The study was conducted at Sekororo District Hospital, South Africa. Methods: Non-cycloplegic near-refractive error data for presbyopic patients who visited the clinic at the district hospital from January 2018 to December 2019 were extracted from the hospital’s records. The records were randomly divided into two groups for 2018 and 2019. Meridional plots and stereo-pair scatter plots were used to analyse the refractive states for the right (OD) and left (OS) eyes. Results: In the 2018 sample, the clinical means for OD and OS were +1.33 ‒0.32 × 90 and +2.01 ‒0.37 × 77, respectively. Similarly, for the 2019 sample, the clinical means for OD and OS were +2.01 ‒0.32 × 82 and +1.82 ‒0.18 × 95, respectively. The data were not normally distributed, and outliers were present. Sample variances were spherical rather than astigmatic. Conclusion: Deviation from the normality showed that the data for OD and OS were mainly mildly positively skewed. Much of the variation in the refractive state was spherical (the stigmatic) irrespective of the laterality.