AIM:To analyze the effect of laser in situ keratomileusis(LASIK)on the accommodative convergence per unit of accommodation(AC/A)ratio in myopic patients.·METHODS:This clinical trial consisted of 40 myopic patients who had bilateral LASIK.The AC/A ratio was measured in the phoroptor with glasses before surgery and 1 week,1 month,3 and 6 months after surgery without glasses.·RESULTS:The average AC/A ratio was(2.98±0.80)△/D with glasses before LASIK,it reduced to(2.02±0.57)△/D,(2.43±0.63)△/D 1 week,1 month after LASIK respectively.There was significant decrease in the AC/A ratio 1 week and 1 month after LASIK(P<0.01).The AC/A ratio recovered to near preoperative values at 3 and 6 months after LASIK,they were(2.87±0.65)△/D,(2.91±0.68)△/D.·CONCLUSION:The AC/A ratio decreases 1 week,1 month after LASIK,it recovers to preoperative value at 3 months after LASIK and keeps stable.·