Changes In Corneal Biomechanics After Artiflex® And Vision® Iclv4c Implantation

To evaluate the changes in dynamic corneal response second-generation parameters and biomechanically corrected intraocular pressure (bcIOP) after Artiflex® and Vision® ICLV4c implantation.

Refractive Surgery Unit of Ophthalmology Department of Centro Hospitalar Universitário do Porto, Oporto, Portugal

Prospective observational study that included eyes submitted to phakic intraocular lens implantation in Centro Hospitalar Universitário do Porto (December 2020 - January 2022). Artiflex® was implanted in 33 eyes and Vision® ICLV4c in 21 eyes. The post-operative medication protocol was equal in both groups. The biomechanical changes were evaluated using OCULUS Corvis® ST, a dynamic Scheimpflyg analyzer. Deformation amplitude ratio at 2.0 mm (DA-Ratio), stiffness parameter at first applanation (SP-A1), Ambrósio relational thickness through the horizontal meridian (ARTh), integrated radius (IR), corvis biomechanical index (CBI), stress-strain Index (SSI) and bcIOP were evaluated before and between month 1 and 3 after surgery.

Fifty-four eyes (28 patients, mean age 30.3±5.2 years old, 67.9% female) were included. The IR was the only parameter that differed between groups (p=0.017). There were no differences in age or spherical equivalent (p>0.08). After surgery, in the Artiflex® group, there was an increase of SP-A1 (93.1±18.6 vs 104.2±28.8, p=0.001), SSI (0.84±0.13 vs 0.93±0.15, p=0.001) and bcIOP (14.1±1.6 vs 16.1±3.8, p=0.001) and a decrease of DA-ratio (4.4±0.4 vs 4.3±0.5, p=0.045) and IR (10.0±1.1 vs 9.3 vs 1.3, p<0.001). There was a tendency to decrease of CBI (0.40±0.29 vs 0.34±0.30, p=0.068) and no changes of ARTh and TBI (p>0.145). In the Vision® ICLV4c group the only significant change was an increase in the SP-A1 (97.4±15.8 vs 109.7±20.5, p=0.015).

Both procedures lead to biomechanical changes, resulting in increased corneal stiffness. A possible explanation may be the effect of the corneal incision and consequent healing, resulting in fibrosis. More parameters changed in the Artiflex® group, comparing to the Vision® ICLV4c. This could be due to the different location of the corneal incision, despite having the same dimension. Considering the stability of CBI and TBI, phakic intraocular lens may be an option for patients with increased pre-operative ectasia susceptibility.