Refractive Shift Following Cataract Surgery: Unveiling Late-Onset Capsular Block Syndrome

Capsular Block Syndrome (CBS) is a rare (<1%) complication of phacoemulsification with posterior chamber intraocular lens (IOL) implantation. Late CBS can occur months to years after surgery, resulting in a gradual decline in visual acuity (VA) due to IOL displacement. We report two cases of CBS, one characterized by a myopic shift and the other by a refractive error. In both cases, Nd:YAG laser capsulotomy resulted in optic clearance, refractive correction, and restoration of VA.

Two case reports of diagnosis and management of late-onset capsular block syndrome. The patients were followed at the ophthalmology department of Hospital de Egas Moniz (Lisbon, Portugal). The pre- and post-Nd:YAG laser capsulotomy refractions, VAs and intraocular pressures (IOP) were compared. The anterior segment was assessed with Haag-Streit BQ 900® LED + IM 900® slit-lamp and Scheimpflug imaging was obtained with Oculus Pentacam®.

Case 1: An 88-year-old man presented with progressive blurry vision in the left eye. He had undergone phacoemulsification with implantation of an IOL (Tecnis® 3-piece IOL ZA9003) 5 years earlier. Best corrected VA was 0.6 (-2.25D). Hospital records from the last appointment 6 months prior showed a VA of 1.0 (-1.75D). IOP was 12mmHg. Slit-lamp examination revealed a distended capsular bag filled with a turbid fluid (retrolenticular pseudohypopyon) and opacification of the posterior capsule (PC) (type 3 CBS). Scheimpflug imaging demonstrated a hyper-reflective band behind the IOL. Following Nd:YAG laser capsulotomy, VA returned to 1.0, IOP decreased to 8mmHg, and both the slit-lamp and Scheimpflug findings resolved. Case 2: A 65-year-old man, also with a history of phacoemulsification with IOL implantation (Tecnis® 1-piece IOL ZCB00) 5 years earlier, presented with the aforementioned complaints. Best corrected VA was 0.2 with an unmeasurable auto-refraction, contrasting with an uncorrected VA of 1.0 measured in the post-operative appointment 4 years before (-0.75x96º). IOP was measured at 14mmHg. A green-colored capsular bag with opaque contents inferiorly (type 4 CBS) was observed on slit-lamp examination. Following Nd:YAG laser capsulotomy (followed by a short steroid taper), VA increased to 1.0, IOP decreased to 10mmHg, and clear optical media were observed on slit-lamp examination, with no signs of inflammation.

CBS should be in the differential for patients with a history of cataract surgery experiencing visual acuity changes, even years after the procedure. Refraction shifts and Scheimpflug imaging aid in the diagnosis, confirmed by a prompt resolution with Nd:YAG capsulotomy. The irido-lenticular complex displacement not only improves visual acuity but is also responsible for a slight decrease in IOP.