The distribution of near point of convergence, near point of accommodation and their association with interpupillary distance in young adults- A cross sectional study

Abstract

Vergence dysfunctions and accommodation anomalies are the main causes of asthenopic symptoms. These may be related to differences in the anthropometric measurements. The anthropometric measurements have a significance in understanding human physical and physiological variations. This study was carried out with the purpose of measuring the near point of convergence (NPC), near point of accommodation (NPA) and to determine their association with interpupillary distance (IPD) in a population of North-western India. This was a cross sectional study carried out on young adults of 18-22 years age group. The NPC and NPA were measured with a Royal Air Force (RAF) scale. Distance IPD was measured with a ruler and autorefractometer. The results were analysed statistically to study the relation of the variables with each other. The average IPD of the study population was 62.18 mm, IICD was 29.65, NPC was 6.55 cm, NPA was 9.42 cm. The correlation between IPD and IICD was 0.15 (weak). The correlation between IPD and NPC was found to be 0.18, correlation between IPD and NPA OD was 0.35 and the correlation between IPD and NPA OS was 0.30, which all were statistically weak. The anthropometric measurements of the study population were similar to those reported by other studies on the Indian population. The correlation between NPA and IPD and that between NPC and IPD was found to be weak.