AIM: To explore the relationship between HbA1c and the changes of retinal and choroidal structures in macular region, and between HbA1c and corrected distant visual acuity before and after cataract surgery in diabetic patients.

METHODS: It is a prospective randomized clinical trial. According to the patient's history, the subjects were divided into the non-diabetes group and the diabetic group. According to the level of HbA1c before operation, the diabetic group was divided into the high HbA1c group(HbA1c>7.0%)and the normal HbA1c group(HbA1c≤7.0%). All 87 eyes from 82 patients who met the criteria from October 2016 to December 2017 in the Department of Ophthalmology at Qingdao Municipal Hospital were enrolled in this study. There were 30 eyes from 28 patients in the non-diabetes group(4%≤HbA1c≤6.0%), 29 eyes from 28 patients in the high HbA1c group and 28 eyes from 26 patients in the normal HbA1c group. Spectral-domain optical coherence tomography(SD-OCT)was used to examine central subifield thickness(CST), central volume(CV)and subfoveal choroidal thickness(SFCT)at 1d before surgery, 1d after surgery, 1wk after surgery, 1mo after surgery and 3mo after surgery. The variance analysis and Pearson correlation analysis were used to analyze the changes and the correlation with HbA1c value. At the same time, the incidence of macular edema after surgery(PCME)was compared among the groups, and the relationship between HbA1c and postoperative corrected distance visual acuity(CDVA)in diabetes patients was also analyzed.

RESULTS: In non diabetic group, high HbA1c group and normal HbA1c group, CST was 239.03+11.55μm, 254.38+26.44μm, 247.07+19.51μm at 1wk after cataract surgery. Their CST was 241.00±11.15μm, 271.55±61.05μm, 248.64±38.28μm at 1mo after cataract surgery(F=3.001, P=0.048). Besides, there was a positive correlation between HbA1c and CST at 1wk and 1mo after operation in the two groups at P=0.01 level(r_1wk=0.338, r_1mo=0.297)(P<0.05). The postoperative macular cystoid edema in non-diabetic group, high HbA1c group and normal HbA1c group were 0, 5(5 eyes, 17%)and 1(1 eye, 4%)respectively. In non diabetic group, high HbA1c group and normal HbA1c group, CDVA was 0.07±0.06, 0.12±0.10, 0.09±0.08 at 1wk after cataract surgery. Their CDVA was 0.03±0.06, 0.11±0.15, 0.11±0.09 at 1mo after cataract surgery. Their CDVA was 0.02±0.04, 0.08±0.12, 0.06±0.06 at 3mo after cataract surgery(F=3.272, P=0.045). The differences among three groups in the CDVA were statistically significant at 1wk, 1mo and 3mo after surgery. There was no significant difference between the high HbA1c group and the normal HbA1c group(P>0.05). However, CDVA(LogMAR)of the two groups was positively correlated with HbA1c at P=0.01 level(r_1wk=0.425, r_1mo=0.235, r_3mo=0.332). There was no statistically significant difference in the changes of CV and SFCT among the three groups, and the trend of changes among these groups was approximately the same.

CONCLUSION: There is a close relationship between the microscopic structure of macula and HbA1c before phacoemulsification in diabetic patients. The risk of macular edema increased in patients with hba1c >7.0% before surgery. The best corrected visual acuity of diabetes patients after surgery was significantly related to the hba1c value before surgery. The higher the hba1c value before surgery, the poorer the improvement of vision after surgery. The level of HbA1c before surgery in diabetic patients is related to the anatomical structure of macular after cataract surgery. The risk of macular edema after surgery is increased in patients with high HbA1c(HbA1c>7.0%)before surgery. Meanwhile, the preoperative HbA1c of diabetic patients is closely related to CDVA after cataract surgery. The higher the preoperative HbA1c value, the worse the CDVA in diabetics after surgery.