AIM: To compare the change of anterior chamber angle(ACA)and vault value before and after implantable collamer lens(ICL)in two implant positions.

METHODS: Randomized controlled study. A total of 83 patients(154 eyes)underwent ICL(V4c, 12.6mm)surgery from 2018 to 2019 were enrolled and divided into two randomly, including into horizontal group(79 eyes)and into vertical group(75 eyes). Pentacam was used to measure the ACA at 0°, 90°, 180°, 270° points before and after implantation and the ACA changes were calculated.

RESULTS: After 12mo, the changes of ACA at 0°, 90°, 180°, 270° position were 15.3°±6.1°, 13.9°±6.3°, 16.5°±5.5° and 12.9°±6.0° in horizontal group while 12.9°±3.7°, 14.5°±6.8°, 14.3°±5.4° and 13.2°±5.9° in vertical group. There was a significant difference in ACA change at 0°-180° position between the two groups(P<0.05). The vault value was 486±183μm, 422±203μm, 393±198μm and 345±165μm in the horizontal group and 432±163μm, 418±138μm, 379±133μm and 328±142μm in the vertical group at 1, 3, 6 and 12mo respectively. The vault value of the horizontal group at 1mo was significantly different from that at 6mo and 12mo after implantation(P>0.05). The vault value of the vertical group at 1mo was significantly different from that at 6mo and 12mo after implantation(P<0.05).

CONCLUSION: During one year after ICL implantation, the ACA changes significantly in horizontal setting than in vertical setting at 0° to 180° points and there is a dynamic decreasing change in vault value.