PURPOSE: To investigate the pharmacological accommodative changes of the anterior segment and its impact on the circumferential anterior chamber angle (ACA) after implantable collamer lens (ICL) implantation using swept-source optical coherence tomography (SS-OCT). SETTING: Eye and ENT Hospital, Fudan University, Shanghai, China. DESIGN: Prospective randomized contralateral eye study. METHODS: 8 men and 24 women (mean age, 28.2 ± 5.8 years
range, 19 to 42 years)
64 eyes were included at 3 months after ICL implantation. One eye per patient was randomly assigned to undergo tropicamide instillation (mydriasis group), and the contralateral eye underwent pilocarpine instillation (miosis group). SS-OCT examinations were performed before and after instillation to measure angle parameters. Trabecular-iris angle 500 (TIA 500 ), angle opening distance 500 (AOD 500 ), trabecular-iris space area (TISA 500 ), angle opening distance circumference area 500 (AODA 500 ), trabecular-iris circumference volume 500 (TICV 500 ), and central vault (ICL to crystalline lens [ICL-L]) were evaluated. RESULTS: Relative to baseline levels, TIA 500 , AOD 500 , and TISA 500 values all increased significantly in both groups (all P <
.01). AODA 500 and TICV 500 values increased by 19.7% and 12.1%, respectively, in the mydriasis group (all P <
.001), and these values similarly increased by 23.4% and 27.7%, respectively, in the miosis group (all P <
.001). After instillation, the ICL-L decrease in the miosis group was significantly larger than that in the mydriasis group ( P = .004). Mean AOD 500 , TISA 500 , and TICV 500 in the miosis group were significantly larger than those in the mydriasis group (all P ≤ .036), especially at 8 and 10 o'clock (all P ≤ .014). Correlation analyses indicated that the increase in ACA parameters was positively correlated with the change in ICL-L for both groups. CONCLUSIONS: Pilocarpine induced a more significant increase in ACA than tropicamide, because of a different mechanism of anterior segment changes. A circumferential meridian scan to assess angle status is recommended.