Nearwork-induced transient myopia in myopic and non-myopic Indian subjects

This research project investigated the characteristics of near-work induced transient myopia (NITM) in asymptomatic myopes and non-myopes among Indian subjects and its variation with target size and contrast. NITM was defined as the post-task distance refraction minus the pre-task distance refraction. In the first two studies NITM magnitude was greater and the decay was faster among myopes for 5 minutes and 60 minutes of near task respectively. There was no influence of target size and contrast on NITM parameters. In the third study Zernike wave-front co-efficient values were measured using COAS (complete ophthalmic analysis system) before and immediately after 5 minutes of near task to investigate the effect of near task on higher order aberrations among myopes and non myopes. Aberration values did not show significant differences for pre and post 5 minutes of near task. In the fourth study axial length, corneal thickness, AC depth and lens thickness were measured with the Bio-graph (Allegro, wave light) instrument before and immediately after 5 minutes of near task to investigate the influence of near task on biometry readings among myopes and non-myopes. Axial length, corneal thickness, AC depth, lens thickness did not show significant differences following 5 minutes of near task. In the fifth study 31 myopes were recruited to assess the NITM parameters in pre and post Lasik refractive surgery. NITM magnitude was higher in pre-Lasik myopic subjects compared to post-Lasik myopic subjects. Most of the accommodative parameters especially the lag of accommodation and facility of accommodation improved following the surgery.