EFFICACY AND SAFETY OF IMPLANTABLE COLLAMER LENS IMPLANTATION IN LOW VAULT CASES: TWO-YEAR FOLLOW-UP

The posterior chamber Implantable Collamer Lens (ICL) phakic intraocular lens (IOL) is usually the first choice for the surgical correction of moderate-to-high myopia. The proper postoperative vault has been considered between 250-750 μm, and low-vault has been associated with cataract formation and toric ICL misalignment. With the introduction of the central Aquaport, the incidence of complications decreased and the intended postoperative vault value is decreasing. The purpose of this study is to describe the efficacy and safety profile of ICL implantation in eyes with low-vault (< 250 μm) over a two-years follow-up period.

Retrospective cohort study including all patients submitted to ICL V4c or V5 implantation for myopia correction at Hospital de Braga, that presented a low vault (< 250 μm) in the first postoperative evaluation (1 month) and a minimum of 2-years follow-up. Patients with previous ocular surgery or pathologies that would affect visual outcomes were excluded.

The study included 124 eyes of 79 patients with a mean age of 34 ± 7 years. ICL size distribution was 12.1 (9.7%), 12.6 (66.9%), 13.2 (21.8%), and 13.7 (1.6%). Eighty five (68.5%) eyes were implanted with a toric IOL. Two-years postoperatively, uncorrected visual acuity was 0.06 ± 0.11 logMAR with an efficacy index of 1.08 ± 0.26, and 75.4% and 93.6% of eyes were within ± 0.50 and ± 1.00 diopters of emmetropia, respectively. Safety index was 1.16 ± 0.24. Spherical equivalent significantly reduced 0.21 diopters from the first postoperative evaluation (-0.08 ± 0.42 D) to 2-years (-0.31 ± 0.42 D). The postoperative central vault significantly reduced from 147 ± 61μm at 1 month postoperatively to 140 ± 64μm at 24 months of follow-up. Endothelial cell density significantly reduced by 3.8% in 2-years (from 2678 ± 222 to 2577 ± 253 cells/mm²). There was no change in mean intraocular pressure during follow-up. We reported 1 case of postoperative ocular hypertension which was controlled with topical hypotensive therapy; 4 cases of toric ICL rotation (3 eyes required lens axis reposition and 1 eye IOL exchange for an higher size); and 1 case of anterior subcapsular peripheral cataract (in which was performed IOL exchanged for an higher size).

ICL implantation for surgical correction of myopia yielded satisfactory visual results with excellent safety and efficacy indexes in patients with low vault. The complication rate was low. This study suggests that ICL may be suitable in cases of low vault and further studies may change our perception of the current ideal vault concept.