Posterior Chamber Phakic Implantable Collamer Lens Implantation With Low-Vault: 5-Year Follow-Up Study

Posterior chamber Implantable Collamer Lens (ICL) phakic intraocular lens is, usually, the first choice for the surgical correction of moderate-to-high myopia. A postoperative vault between 250-750μm is, typically, desired, and low-vault raises concern about higher risk of cataract formation and Toric ICL misalignment. The introduction of the central aquaport decreased the incidence of several complications and lowered the threshold of postoperative vault.

Department of Ophthalmology, Hospital de Braga, Portugal.

Retrospective, comparative study of patients that underwent ICL implantation in our department and who completed a 5-year follow-up. Inclusion criteria: age ≥ 21 years; stable refraction  >12 months; no previous ocular surgeries; an anterior chamber depth (ACD) ≥2.80mm. According to the central vault at 1 month, two groups of patients were created: Group 1 (Low Vault < 250μm) and Group 2 (Normal Vault - 250 to 750μm). Visual, refractive and tomographic data were collected. A total of 87 eyes from 55 patients in Group 1 and 159 eyes of 96 patients in Group 2 were included in the study who completed the 5-year follow-up.

The groups differed significantly in preoperative ACD, white-to-white and ACA. In group 1, 67.8% had a 12.6mm ICL implant and 65.2% in Group 2 were 13.2mm (p<0.001). There were 62.1% toric ICL in Group 1 and 49.7% in Group 2. Mean postoperative vault at 1 month was 120 ±140 and 400 ±150, respectively. At 5 years, the safety and efficacy indexes were similar in both groups (p=0.413, p=0.458, respectively). Around 75.9% and 69.9% eyes were within ±0.50 D of target refraction. Vault significantly decreased in group 2 (p<0.001). There were no significant differences between groups regarding ECD or ECD rate loss (p=0.116; p=0.571, respectively). No vision threatening complications were reported.

ICL implantation yielded good visual and refractive results with excellent safety and efficacy indexes. These results were also seen in patients with low vault evaluated during a long-term follow-up. The complication rate was low and similar to a normal vault population. This study suggests that ICL with low vaults has good results and few complications and further studies may change our perception of the current ideal vault concept.