Changes in ocular parameters of the crystalline lens after implantation of a collamer lens

Clinical relevance Understanding changes in ocular anatomical parameters after intraocular lens implantation will allow a more accurate determination of dioptric power prior to surgery.Background The crystalline lens position might change due to the implantation and removal of an implantable collamer lens (ICL) or toric implantable collamer lens (TICL). This study aimed to assess the effect of ICL implantation on position of the crystalline lens.Methods This retrospective study was conducted on patients who underwent V4c ICL or V4c TICL implantation between March and September, 2018. Preoperative and post-operative (2 weeks, 3 months and 6 months) axial length, central corneal thickness, crystalline lens position, crystalline lens thickness and vault height were analysed. Multivariable linear regression was used to determine the variables associated with 6-month changes in lens position.Results This study included 117 eyes of 117 patients. There were decreases in all vertical distance measures from the central corneal endothelium to the anterior and posterior crystalline lens capsule (all p > 0.05). The amount of reduction was related to the crystalline lens position before the operation and crystalline lens thickness after the operation (all p < 0.01). An error in anterior chamber depth and lens thickness may appear when the ICL/TICL is close to the crystalline lens.Conclusion Phakic intraocular lens implantation resulted in lens thickening and forward movement on day 1 post-operatively, which becomes stable within 6 months. Preoperative lens position and post-operative lens thickness were related to the amount of movement.