RESUMO
AIM: To analyze the changes of uncorrected distance visual acuity(UCDVA)and ocular accommodation before and after excimer laser photorefractive keratectomy(PRK).METHODS: A retrospective study. There were 120 patients(240 eyes)who underwent PRK surgery in our center from December 2017 to December 2019 divided into two groups according to the diopter of spherical equivalent(SE): 70 cases with SE≤-6.00D in the mild to moderate myopia group and 50 cases with -6.00D<SE≤-9.00D in the high myopia group which were observed and analyzed. The UCDVA(LogMAR), monocular accommodative amplitude(AMP), negative relative accommodation(NRA), positive relative accommodation(PRA)and monocular accommodative flipper(AF)were measured before and after operation at 1wk, 1 and 3mo. RESULTS: In the group of low-moderate myopia and high-myopia group, the UCDVA at 1wk, 1 and 3 mo after operation was significantly increased compared with those before operation(all P<0.01). The increase of UCDVA of low to moderate myopia group was better than that in the high myopia group at 3mo after operation(P<0.05). Monocular AMP in the both groups firstly decreased and increased afterwards, and there was a significant decrease than that before operation at 1wk and 1mo after operation(P<0.01). AMP reached and was better than that before operation at 3mo after operation(P<0.01). The increase of low to moderate myopia group was both higher and faster than that of high myopia group. Compared with PRA before operation, the patients of low to moderate myopia group decreased at 1wk after operation(P<0.01), postoperative levels at 1mo recovered to preoperative level(P>0.05)and postoperative at 3mo was superior to preoperative operation(P<0.05); High myopia group did not change significantly at 1wk and 1mo after operation compared with preoperative operation(P>0.05), and increased at 3mo after operation compared with preoperative level(P<0.01). For low to moderate myopia group, there was no significant difference in preoperative and postoperative NRA, and at 1wk after operation, NRA of high myopia group temporarily increased compared with preoperative operation(P<0.01). At 1mo after operation, it returned to the preoperative level(P>0.05), and significantly increased at 3mo after operation compared with preoperative operation(P<0.01). Monocular AF for both groups significantly decreased at 1wk after operation compared with preoperative operation, recovered at 1mo after operation and was significantly better at 3mo after operation(all P<0.01); The low-to-moderate group increased more than the high-myopia group.CONCLUSION: PRK has a good correction effect for myopia below -9.00D, and people in low to moderate myopia have a better postoperative UCDVA correction effect than those in high myopia. The eye accommodation will be abnormal in a short period after operation. The recovery and improvement time of accommodative function in low-moderate myopia group are shorter than that in high myopia group, but both groups can recover and improve at 3mo after operation compared with the preoperative levels.