Pupil barycenter configuration in patients with myopia and hyperopia

Purpose To compare the pupil barycenter configurations that can be used to calculate the kappa angle in terms of distance in patients with myopia and hyperopia. Method : This prospective study evaluated 394 eyes of 197 patients. The patients were divided into two groups according to their spherical equivalent values: the myopic group (mean spherical equivalent refraction < − 0.50 D) and the hyperopia group (mean spherical equivalent refraction > + 0.50 D). The two groups were further subdivided according to severity (myopic group: mild, <−0.50 and ≤ − 3.00 D; moderate, <−3.00 and ≤ − 6.00 D; severe, <−6.00 D; hyperopic group: mild, ≥+0.50 and ≤ + 2.00 D; moderate, >+2.00 and ≤ + 4.00 D; severe, >+4.00 D). The pupil and iris barycenter distance measurements and other parameters were obtained through optical low-coherence reflectometry. Results Of the 197 patients, 109 (55.3%) were female and 88 (44.7%) were male, and their age ranged from 7 to 60 years (mean, 35.16 ± 14.75 years). The average pupil barycenter measurements originating from the kappa angle distances were 0.38 ± 0.15 and 0.21 ± 0.11 mm in patients with hyperopia and myopia, respectively. Corneal and lens thickness measurements were higher in patients with hyperopia, whereas anterior chamber depth and pupil diameter measurements were higher in patients with myopia. No significant difference in astigmatism or white-to-white measurements was observed between patients with hyperopia and those with myopia. Conclusion The kappa angle distances are higher in hyperopia than in myopia. The pupil barycenter measurement from the kappa angle distance can be an alternative for the evaluation of the kappa angle.