This thesis investigates long-term outcomes and safety of phakic intraocular lens implantation for refractive correction. It evaluates postoperative visual performance, adverse events including endothelial cell loss, and indications for secondary interventions during extended follow-up. The analyses show that pIOL implantation can provide durable refractive benefit when patients are selected carefully and monitored systematically. The work defines key risk factors and supports lifelong surveillance strategies to optimize patient safety and treatment durability.