Flipped implantable collamer lens causing angle closure and creating a unique challenge for intraocular lens calculation.

Extreme myopic laser-assisted in situ keratomileusis (LASIK) poses challenges regarding future intraocular lens (IOL) power selection. A male patient in his 40s complained of progressive right eye (OD) diminished visual acuity. He had a history of myopic LASIK in both eyes (OU) 20 years before, and implantable collamer lens (ICL) implant in OU 8 years before. The best-corrected visual acuity (BCVA) was 20/63OD (+2.00-4.00 ×80), with a posterior subcapsular cataract OD and intraocular pressure of 30 mm Hg. Anterior segment optical coherence tomography revealed an upside-down ICL. Lens explantation followed by cataract surgery was decided. The American Society of Cataract and Refractive Surgery IOL power calculator for prior myopic LASIK was used to determine the IOL power and a monofocal IOL was implanted. One month later, the distance BCVA was 20/32. The IOL power calculation and selection were particularly challenging given the extreme biometric data. In such cases, careful preoperative assessment is critical to achieve a successful result.