Reduction in maximum ciliary body thickness could be a pre-existing predictor for pseudophakic malignant glaucoma

Objective: Malignant glaucoma is a rare and vision threatening form of glaucoma occurring in certain postoperative patients. It presents difficult diagnostic challenge. Dentification of morphometric indicators enables to predict the development of pseudophakic malignant glaucoma (PMG). Methods: A retrospective cross-sectional study was conducted from June 2016 to May 2023. Patients who originally diagnosed with primary angle closure glaucoma and developed PMG after phacoemulsification were recruited, while those without PMG were matched eyes. The parameters such as central anterior chamber depth (ACD), trabecular-ciliary process angle (TCA), ciliary body thickness (CBTmax, CBT0 and CBT1000), and anterior placement of ciliary body (APCB) were measured by ultrasound biomicroscopy (UBM) at pre-onset, onset and 6-month after settlement of PMG. Results: A total of 60 eyes from 60 patients were recruited. No significant difference was found in the baseline characteristics such as age, best-corrected visual acuity, intraocular pressure, degrees of angle closure and axial length. Lens extraction markedly increased the CBTmax (0.95 ± 0.09 mm vs. 1.05 ± 0.11 mm), CBT0 (0.85 ± 0.11 mm vs. 0.92 ± 0.13 mm) and TCA (62.61 ± 13.17 mm vs. 70.92 ± 10.65 mm) in matched eyes, but no such increases were observed in those developed PMG. Notably, among these parameters at pre-onset of PMG, a significant reduction of CBTmax (0.87 ± 0.09 mm vs. 0.95 ± 0.09 mm, P = 0.001) was only detected in the eyes that developed PMG, when compared to the matched eyes. These findings suggest an early predictor of CBTmax for PMG occurrence. Subsequently, zonulo-hyaloido-vitrectomy was performed to resolve the PMG, which was accompanied with a significant increase in the ACD, CBTmax, CBT0 and TCA, but not CBT1000 and APCB. Moreover, at pre-onset of PMG, CBTmax was the only factor producing significant prognostic value (0.74 [95% CI, 0.61-0.87], P = 0.001), which almost reaches the predictive ability at PMG attack (0.86 ([95% CI, 0.76-0.96], P < 0.001). Conclusion: A reduction in thickness of the ciliary body is pre-existed in the eyes with PMG, of which a reduced CBTmax may serve as an early predictor.