A case of enlarged primary iris cyst developing two years after implantable collamer lens implantation

Purpose: We report a case of refractive error caused by a presumably enlarged primary iris cyst that developed two years after Implantable Collamer Lens (ICL) implantation and was successfully treated with surgical excision. Observations: A 33-year-old man presented to our clinic with persistent hyperemia in the left eye for two months and decreased vision for seven days. He underwent bilateral ICL implantation at another hospital two years prior to the visit. Anterior-segment optical coherence tomography and ultrasound biomicroscopy revealed a primary iris cyst in the inferotemporal quadrant of the left eye. His corrected distance visual acuity (CDVA) was 20/17 (-0.079) with refractions of +1.25 D/-3.50 D × 175° in the left eye. The cyst was presumed to cause posterior displacement and tilting of the ICL, leading refractive errors in the left eye. Two months after observation without improvement, the patient underwent surgical excision of the cyst using a vitrectomy cutter. Three months postoperatively, his CDVA was 20/14 (-0.176) with refractions of -0.50 D in left eye. The ICL had returned to the proper position and refractive errors in the left eye had improved. Conclusion and importance: This case highlights the fact that primary iris cysts could enlarge after ICL implantation, leading to significant refractive changes. Careful long-term follow-up is essential. Furthermore, surgical excision may be an effective treatment option for managing ICL malpositioning and associated visual disturbances.