Imaging and refractive characteristics of different types of late postoperative capsular block syndrome

To propose a novel classification system for late postoperative capsular block syndrome (CBS) based on the turbidity of intracapsular fluid, and to investigate the imaging and refractive changes before and after Nd:YAG laser posterior capsulotomy for each subtype.

A retrospective analysis was performed on 5 eyes from 5 patients with late postoperative CBS. Patients were categorized into turbid (3 eyes) or clear (2 eyes) types based on the turbidity of intracapsular fluid. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refractive status, slit-lamp images, Pentacam Scheimpflug data, and ultrasound biomicroscopy (UBM) images were evaluated before and 1mo after successful Nd:YAG laser posterior capsulotomy.

Nd:YAG laser posterior capsulotomy significantly improved UCVA and BCVA in all 5 late CBS eyes. Pentacam imaging: turbid intracapsular fluid showed hyperreflection between posterior capsule and intraocular lens (IOL); clear fluid showed hyporeflection. UBM: posterior capsule was clear in turbid type but poorly defined in clear type. Capsulotomy increased aqueous depth only in clear type. Refractive changes: turbid fluid induced myopic shift. Clear type myopic shift was due to anterior IOL displacement and clear fluid-induced concave lens effect.

Nd:YAG laser posterior capsulotomy is effective for late CBS. Turbid and clear late CBS types differ in imaging (Pentacam/UBM) and refractive mechanisms, supporting the proposed classification's clinical value.