Posterior Chamber Phakic Implantable Collamer Lens V4c And V5 In Different Depths Of Anterior Chamber – A Comparative Retrospective Study

Phakic lens implantation for treatment of myopia is an effective and safe surgical procedure, whose complication rate may vary depending on the anatomical characteristics of the anterior segment. The aim of this study is to evaluate the efficacy, safety and predictability of the posterior chamber lens implant procedure in two groups of patients: anterior chamber depth below and above 3.00 mm.

Retrospective, comparative study of patients that underwent surgery for implantation of posterior-chamber phakic Implantable Collamer Lens (ICL), model V4C or V5, for myopia treatment, in the Ophthalmology Department of Hospital de Braga, between 2012 and 2020

Inclusion criteria: age ≥ 20 years, refraction stability > 12 months, primary procedure with no other previous eye surgeries, anterior chamber depth (ACD) measured at the endothelium equal to or greater than 2.80 mm, minimum follow-up of 12 months. Two groups of patients were created: Group 1 (ACD up to 2.99 mm) and Group 2 (ACD equal to or greater than 3.00 mm). The parameters evaluated were uncorrected and best-corrected visual acuity, subjective refraction, efficacy and safety index, predictability curve, mean endothelial cell density, mean central Vault, anterior chamber angle and postoperative complications. A total of 558 eyes from 298 patients were evaluated: 111 eyes (19.9%) in group 1 and 447 eyes (80.1%) in group 2.

At 12 months, the efficacy index was similar in both groups (p=0.264); the safety index was higher in group 1 (p=0.031); the mean central Vault was significantly lower in group 1 (212,8 vs 410,6 μm; p<0.001) and significantly decreased throughout the follow-up. Respectively, 93 (83.8%) and 366 (84.1%) eyes were within ±0.50 D of targeted refraction and postoperative manifest refraction changes were −0.09 ± 0.35D and −0.10 ± 0.33D. Anterior chamber angle significantly decreased during follow-up in both groups (p<0.001; p<0.001). Intraocular pressure did not change significantly (p=0.310 and p=0.446, respectively). There were no significant differences in endothelial cell density (p=0.278) or in the rate of complications observed (p=0.733).

Posterior-chamber phakic lens ICL implantation is an effective and safe procedure in narrow anterior chambers (2.80 to 3.00 mm), with visual and refractive results and complication rate identical to those obtained in chambers greater than 3.00 mm. Closer follow-up is required in the subgroup of patients with reduced central vault measurements in order to detect early complications.