Anterior Segment Pharmacological Accommodative Changes and Its Impact on the Circumferential Anterior Chamber Angle after ICL V4c Implantation: Angle following ICL implantation.

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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). Eye and ENT Hospital, Fudan University, Shanghai, CHINA. Prospective randomized contralateral eye study. Eight men and 24 women (mean age, 28.2 ± 5.8 years; range, 19-42 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 (TIA500), angle opening distance 500 (AOD500), trabecular-iris space area (TISA500), angle opening distance circumference area 500 (AODA500), trabecular-iris circumference volume 500 (TICV500), and central vault (ICL to crystalline lens [ICL-L]) were evaluated. Relative to baseline levels, TIA500, AOD500, and TISA500 values all increased significantly in both groups (all P < 0.01). AODA500 and TICV500 values increased by 19.7% and 12.1%, respectively, in the mydriasis group (all P < 0.001), and these values similarly increased by 23.4% and 27.7%, respectively, in the miosis group (all P < 0.001). After instillation, the ICL-L decrease in the miosis group was significantly larger than that in the mydriasis group (P = 0.004). Mean AOD500, TISA500, and TICV500 in the miosis group were significantly larger than those in the mydriasis group (all P ≤ 0.036), especially at 8 and 10 o'clock (all P ≤ 0.014). Correlation analyses indicated that the increase in anterior chamber angle parameters was positively correlated with the change in ICL-L for both groups. Pilocarpine induced a more significant increase in ACA than tropicamide, because of different mechanism of anterior segment changes. We recommend circumferential meridian scan to assess angle status.