Low Diopter Toric Implantable Collamer Lens For Astigmatism Correction: 5 Years Follow-Up

To evaluate the efficacy and safety profile of the correction of low power astigmatism with toric phakic lenses over a five-years follow-up period.

Implantable collamer lenses (ICL) are a type of posterior chamber phakic intraocular lens. Generally, they are used for moderate to high degrees of ametropia or when corneal refractive surgery is contraindicated. In these cases, ICL implantation is a promising alternative because it involves no change of corneal tissue, are implanted through a small clear corneal incision, allowing the preservation of the crystalline lens, ensuring that the natural lens functions are maintained.

Retrospective analytical study was designed and included all patients submitted to ICL implantation for low astigmatism correction (<2.00 Diopters) at Hospital de Braga, Portugal, between 2018 and 2023, with a minimum follow-up of 5 years.

The study enrolled 56 eyes. Mean age of patients was 34±8 years-old, with previous average refraction in spherical equivalent of -8.93±3.08D. Average preoperative astigmatism was -1.66±0.54 cylindric diopters. During and at the end of follow-up, the efficacy index and the safety index were higher than 1.0. One month after surgery, average residual astigmatism was -0.32±0.59D and remained stable at 5 years, with an average residual astigmatism of -0.39±0.68D. Mean vault and IOP at 5 years was 272.41±143.05 μm and 15.50±3.02 mmHg respectively. Mean central endothelial cell density decreased from 2661.73±180.53 cells/mm2 after ICL implantation, to 2565.20±210.61 cells/mm2 at the end of the follow up, representing a 3.88% endothelial cell loss.

This 5-year follow-up study demonstrated that low diopter toric ICL implantation in low astigmatism is a predictable, stable, safe, and effective procedure with high efficacy and security indexes.