Unexpected Effective Power Of Toric Implantable Collamer Lens (Ticl) Leading To Postoperative Refractive Surprise: A Case Report

This is a case of postoperative refractive surprise caused by the mismatch between labeled and actual refractive power of a toric implantable collamer lens (TICL). 

Department of Ophthalmology, the First Affiliated Hospital of Xi’an Jiaotong University. Preoperative and postoperative assessments included comprehensive ophthalmic examination, including uncorrected (UCVA) and best-corrected visual acuity (BCVA), manifest refraction (MR) and cycloplegic refraction, intraocular pressure (IOP) measurement, and anterior segment imaging (OCT for vault measurement). 

A 37-year-old man with MR of -14.50/-1.50x30° in the right eye (OD) and -14.50/-1.00x175° in the left eye (OS) underwent bilateral phakic intraocular lens implantation: OD 13.2-mm TICL (-16.50/+1.00/115° with 5° counter-clockwise rotation) and OS 13.2-mm ICL (-15.50 D).  On postoperative day 1, OD UCVA was 12/20 with a residual refraction of -1.00/-1.25x35°, despite an optimal vault (690 μm) and confirmed alignment with the intended TICL position. The left eye achieved satisfactory outcomes. At week 2, the right eye’s residual astigmatism persisted (-1.00/-0.75×50°). Two possibilities were considered: 1) an inaccuracy in preoperative manifest refraction (the ‘correct’ preoperative MR was calculated to be -16.69/-1.04×106°), 2) an unexpected effective power of the implanted TICL (calculated ‘actual’ refractive power was intended to correct a MR of -13.35/-1.04×16°). Attributing the surprise most likely to the latter, a decision was made to rotate the TICL by an additional 10° counter-clockwise to a final axis of 15°. One day after repositioning, OD UCVA improved to 16/20 with a refraction of -0.75/-0.75x35°. At week 7, UCVA was stable at 16/20, BCVA was 20/20, with a final refraction of -0.75/-0.50x30° and a stable vault. The patient was satisfied with the final visual outcomes. Retrospective calculation based on the results after the second surgery verified that the refractive surprise was caused by the unexpected effective power of the implanted TICL.

A postoperative refractive surprise after TICL implantation requires systematic analysis. Although the mismatch between labeled and actual refractive power of TICL is rare, it should be considered after excluding other possible factors such as TICL rotation, corneal incision-related astigmatism, and inaccurate preoperative refraction. In this case, surgical repositioning of the TICL was a safe and effective intervention to optimize visual outcomes.