Comparison of convergence insufficiency between different refractive states of the eye

Abstract

BACKGROUND: To determine the relationship between convergence insufficiency and different refractive errors, and to determine the magnitude of convergence insufficiency.

METHODS: A hospital-based descriptive cross-sectional study was conducted at Haji Murad Eye Trust Hospital Gujranwala including 100 patients of age between 15 to 35 years. Visual acuity of all the patients was recorded and subjective refraction was performed. The convergence insufficiency was recorded on the basis of the near point of convergence (NPC). It was measured subjectively using cm ruler.

RESULTS: A total of 100 patients aging 15-35 years including males and females in equal proportion were assessed for remote near point of convergence to find the magnitude of convergence insufficiency. 35 patients were myopic, 35 hypermetropic and 30 were astigmatic. Out of 35 myopic patients 16 (45.71%) were having 18 cm near point of convergence (NPC), 10 (25.57%) 17cm NPC and 9 (25.71%) 16cm NPC. The values for near point of convergence in hypermetropic patients were opposite to those of myopic. Out of 35 subjects, 28 (80%) were having 10cm of NPC while other 9 (20%) 12 cm. In this study, the astigmatism was showing variation from myopia and hypermetropia. 10 (33.3%) out of 30 astigmatic subjects were measured 10cm as their NPC,2 patients (6.67%) 12cm, 1 patient (3.33%) 13cm, 2patients (6.67%) 14cm, 4 patients (13.33%) 15cm, 4 patients (13.33%) 16cm, 4patients (13.33%) 17cm and 3patients (10%) 18cm.

CONCLUSIONS: There is a weak relationship between refractive errors and convergence insufficiency. Myopia is the only contribution to remote near point of convergence.