Potential harms of posterior chamber phakic IOL: a systematic review and meta-analysis of complication incidence

Topic
To estimate the incidence of complications after posterior chamber phakic intraocular lens implantation and to evaluate temporal and geographic variation in reported outcomes.
Clinical Relevance
PCPIOLs are widely used for refractive correction, yet uncertainty persists regarding the true frequency of mechanical, anterior-segment, and posterior-segment complications. Reliable incidence estimates are essential for patient counseling and postoperative management.
Methods
This systematic review and meta-analysis included randomized and nonrandomized trials and observational studies involving adults undergoing posterior chamber phakic intraocular lens implantation. PubMed, Scopus, WANFANG Data, and China National Knowledge Infrastructure were searched through May 2024 without language or date restrictions. The primary outcome was the incidence of IOL explantation. Secondary outcomes included the onset of IOL rotation or displacement, anterior capsular opacification, cataract formation, iris atrophy, retinal detachment, macular oedema, pupillary block, glaucoma, pupil ovalisation, intraocular infection, endothelial failure, and iris cyst. Risk of bias was assessed using a modified Newcastle–Ottawa Scale. Incidence was modeled as events per 1,000 person-years using negative binomial regression with robust variance. The protocol was registered in PROSPERO (CRD42024527190).
Results
A total of 214 studies (45,027 eyes) were included, most involving the V4c model of the Implantable Collamer Lens (92.7%). Rotation or displacement occurred at 4.2 per 1,000 person-years and explantation at 3.1 per 1,000 person-years, corresponding to approximately about 2 rotated lenses and explantations per 100 eyes followed for 5 years, assuming constant hazards. Anterior segment events were less frequent, and posterior events were rare (retinal detachment, 0.4; macular edema, 0.3 per 1,000 person-years). Complication rates decreased in more recent studies and were lower in Asian cohorts.
Conclusions
PCPIOL implantation is associated with a low incidence of complications, and vision-threatening events appear to be very rare. However, predominantly short follow-up and high risk of bias likely lead to underestimation of late events. These incidence estimates support early postoperative assessment of centration, axis alignment, and vault, and long-term endothelial and anterior segment monitoring.