We report a case of late-onset capsular block syndrome, which resulted in a misdiagnosis of intraocular lens (IOL) opacity.

A 59-year-old man visited our clinic with reduced visual acuity in the right eye from 1 year prior. He had undergone uncomplicated bilateral cataract surgery by phacoemulsification with IOL implants at another hospital 10 years before. There was no specific history with the exception of hypertension. After being diagnosed in the ophthalmology clinic with IOL degeneration and opacity in the right eye, he was referred to our hospital for IOL replacement. Upon examination, his right uncorrected visual acuity was 0.06 and intraocular pressure was 22 mmHg. The refractive error could not be checked due to IOL opacity. Slit-lamp microscopy revealed a cloudy, milky IOL. Anterior-segment optical coherence tomography of the right eye showed retention of a highly reflective material in the lens capsule behind the IOL. Posterior capsule enlargement of the right eye was confirmed on ultrasound biomicroscopy. After neodymium-doped yttrium aluminium garnet (Nd:YAG) laser capsulotomy was performed, the homogeneous space disappeared and the eye recovered normal visual acuity.

Capsular block syndrome is a rare complication that can occur shortly (1 day to 2 days) after cataract surgery. Late-onset capsular block syndrome, which occurs 10 years after surgery differs from typical clinical manifestations. Thus, capsular block syndrome is an important consideration upon the presentation of opacification due to IOL degeneration.