PURPOSE: To quickly examine the long-term retained oily-like material on the intraocular lens (IOL) of a sutureless cataract surgical patient. DESIGN: Observational case report. METHODS: Fourier transform infrared (FT-IR) and confocal Raman microspectroscopies were used to identify the deposited materials on explanted IOL. RESULTS: A 70-year-old man underwent a sutureless cataract surgery for his right eye. Garamycin ophthalmic ointment was postoperatively applied on the conjunctival fornix. His vision was improved to 20/25 after surgery but declined gradually to 20/400 half a year later. An oily-like hump on the anterior surface of IOL was found and he underwent IOL exchange after approximately 3 years. The oily-like material was identified by using FT-IR and Raman microspectroscopies to be garamycin ophthalmic ointment. CONCLUSIONS: Both FT-IR and Raman microspectroscopies can easily examine the retained antibiotic ophthalmic ointment on the IOL. Direct access of ophthalmic ointment into ocular anterior chamber through the sutureless incision is a potential risk.