Association between Offset of the Pupil Center from the Corneal Vertex and Wavefront Aberration

Abstract

PURPOSE:To investigate the influence of offsets of the pupil center from the corneal vertex on wavefront aberrations in the anterior cornea and the whole eye. METHODS: Both right and left eyes of 103 subjects were measured for the wavefront aberrations in the anterior cornea, along with the offset of the pupil center relative to the corneal vertex, using a Humphrey corneal topographer, and for the wavefront aberration in the whole eye using a WASCA wavefront sensor. Correlations of the pupil center offsets with the Zernike aberrations were tested. RESULTS: X-axis shift of the pupil center from the corneal vertex was significantly correlated to horizontal coma for both the right (r = 0.54, P<0.0001) and left eyes (r=0.48, P<0.0001) in the cornea, but was weakly correlated to the coma in the whole eye (r=0.17, P=0.04 for OD; and r=0.17, P=0.05 for OS). Significant but weak correlations with the x-axis pupil center shift were also found for several other Zernike aberrations, including the oblique astigmatism, vertical trefoil and secondary astigmatism. Very few Zernike aberrations were significantly correlated to y-axis pupil center shift. Most Zernike aberrations were significantly correlated between the right and left eyes to produce bilateral symmetry in the cornea and the whole eye. CONCLUSIONS:The results suggest that offset of the pupil center from the corneal vertex plays an important role in determining horizontal coma and few other Zernike aberrations. Factors controlling bilateral symmetry of the wavefront aberrations between the two eyes could make important contributions to wavefront aberrations in the human eye. (J Optom 2008;1:8-13 ©2008 Spanish Council of Optometry) KEY WORDS: wavefront aberration; angle lambda; pupil center; corneal vertex; bilateral symmetry. RESUMEN OBJETIVO:Investigar el efecto que tiene el descentramiento de la pupila con respecto al vértice corneal sobre las aberraciones del frente onda asociadas tanto a la cara anterior de la córnea como a la totalidad del ojo. MÉTODOS: En los ojos derecho e izquierdo de 103 sujetos se midieron las aberraciones del frente de onda asociadas tanto a la cara anterior de la córnea (utilizando un topógrafo corneal Humphrey), como a la totalidad del ojo (utilizando un sensor de frente de onda WASCA). Asimismo, se midió el desplazamiento del centro de la pupila respecto a la posición del vértice corneal, utilizando el mismo topógrafo corneal Humphrey anteriormente mencionado. Se investigó la posible correlación entre el valor del desplazamiento del centro de la pupila y los distintos términos de aberraciones de Zernike. RESULTADOS: El desplazamiento según el eje x del centro de la pupila respecto al vértice corneal muestra una correlación significativa con el valor del coma horizontal en la córnea tanto para los ojos derechos (r=0,54; P<0,0001) como para los izquierdos (r=0,48; P<0,0001); sin embargo, existe una correlación muy débil entre el valor de este desplazamiento y el coma de toda la óptica ocular (r=0,17; P=0,04 para OD; y r=0,17; P...

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