A Study to Compare Accommodative Convergence Over Accommodation (AC/A) Ratio When Myopic Patient Changes from Spectacles to Contact Lenses

Description

Abstract (English)

Abstract
Aim: The aim of the present study was to compare accommodative convergence over accommodation (AC/A)
ratio when Myopic patient changes from Spectacles to Contact lenses.
Methods: A Prospective, cross-sectional study included 50 myopic subjects in the Department of Ophthalmology,
Nalanda Medical College and Hospital, Patna, Bihar, India from July 2017 to June 2018. Written informed consent
was obtained from all the subjects who were included in the study. Subjects who had spherical myopia from at
least –0.75 DS to -6 of both eyes, an astigmatic ametropia ≤1.00 D and anisometropia.
Results: There was no statistically significant difference in amplitude of accommodation by either method (pushup and minus lenses) P: 0.102, P: 0.059 respectively. But the means of accommodative amplitude by all methods
increased with contact lenses as compared to the spectacle lenses. Fusional vergence (positive and negative)
showed no significant difference when wearing spectacles compared to soft contact lenses P: 0.317 in both. The
positive Fusional vergence mean increased with contact lenses as compared to the spectacles and the negative
fusional vergence mean decreased with contact lenses as compared to the spectacle. Stimulation horizontal
dissociated phoria (with+3DS and - 3DS) showed less exophoric values in near and more esophoria values in
distance with contact lenses as compared to spectacles with no significant difference P:0.180 and P:0.317
respectively. There were no significant differences in both AC/A ratio while using gradient and heterophoria
methods when subjects changed from spectacles to contact lenses P:(0.285, 0.317) with +/-3DS in gradient method
respectively and P:0.317 in heterophoria method.
Conclusion: No significant change in the AC/A ratio has been found when myope shifts from spectacles to contact
lenses. Although there was increase in accommodation amount, increase in convergence and reduction of
horizontal exophoria at near when use contact lenses, which should be considered when myopic patients become
symptomatic when shift from spectacles to contact lenses.