Reduction Of Pre-Existing Astigmatism Following Spherical Icl Implantation In Eyes With Posterior Chamber Abnormalities: A Clinical Observation Of Staged Refractive Surgery

To evaluate the clinical efficacy of a staged "Bioptics" approach (initial spherical ICL implantation followed by scheduled corneal laser refractive surgery) in highly astigmatism patients with posterior chamber  abnormalities unsuitable for Toric ICL (TICL), and to investigate the patterns of residual astigmatism changes following spherical ICL surgery.

This prospective study included 20 eyes with abnormal posterior chamber structures (e.g.,a wide posterior chamber angle or ciliary body abnormalities). The surgical protocol involved primary spherical ICL implantation to correct myopia, followed by LASIK refinement for residual astigmatism 3 month postoperatively. Manifest refraction and corneal topography were performed to compare total eye astigmatism and corneal astigmatism at three stages: preoperative, post-ICL, and post-LASIK. Refractive outcomes, including Uncorrected Distance Visual Acuity (UDVA) and corrected distance visual acuity (CDVA)were analyzed.

 Post-ICL, 80% and 100% of eyes achieved a UDVA of $\ge$ 20/20 and $\ge$ 20/25, respectively. Total eye astigmatism decreased significantly by $1.45\pm 0.25$ D to a residual of $2.25\pm 0.65$ D. In contrast, corneal topography showed only a minor change ($-0.25\pm 0.11$ D). This discrepancy suggests that astigmatic reduction was primarily driven by intraocular optical realignment rather than corneal surface modification. The staged approach effectively bypassed TICL rotation risks in irregular anatomy, ensuring a stable baseline for subsequent LASIK.

For patients with abnormal posterior chamber structures, the staged "Bioptics" approach is highly effective. The primary implantation of a spherical ICL induces a notable "spontaneous" reduction in total eye astigmatism ($1.45$ D on average). This phenomenon suggests that preoperative astigmatism measurements may overestimate the final requirement for laser correction, highlighting the necessity of re-evaluating manifest refraction post-ICL to ensure precise second-stage laser ablation and avoid overcorrection.