Pigment dispersion syndrome and pigmentary glaucoma: overview and racial disparities

Pigment Dispersion Contributes to Ocular Immune Privilege in a DBA/2J Mouse Model of Pigmentary Glaucoma

Purpose

To investigate the effects of anterior chamber pigment dispersion on ocular immune privilege and the possible mechanisms involved in a DBA/2J mouse model of pigmentary glaucoma.

Methods

DBA/2J mice were utilized as a pigment dispersion model, and age-matched C57BL/6J mice were used as the control group in this study. Proteins in the aqueous humor (AH) and serum were quantified using the bicinchoninic acid assay. Immune cells in the AH were detected using hematoxylin and eosin staining and immunocytochemistry. The expression of TGF-β2 in the AH and cytokine levels (IL-10, IFN-γ) in serum were measured using ELISA. Anterior chamber-associated immune deviation (ACAID) was induced in DBA/2J mice by injecting antigens into the anterior chamber. Delayed-type hypersensitivity (DTH) assays were used to assess the induction of ACAID. In DBA/2J mice, before and after pigment dispersion, following anterior chamber injection of pigment particles, and after ACAID modeling, the expression of regulatory T cells (Tregs) was detected using flow cytometry.

Results

Compared to C57BL/6J mice, the protein concentration, immune cell count, and TGF-β2 levels in the AH were elevated in DBA/2J mice. Protein concentration and IL-10 levels in serum were increased, while IFN-γ levels were decreased in DBA/2J. Additionally, the expression of Treg cells in the spleen of DBA/2J mice was significantly increased after pigment dispersion and anterior chamber injection of pigment particles. At 3 and 6 months, DTH responses in DBA/2J mice were not inhibited, thus preventing ACAID induction. However, the opposite was observed at 9 months in DBA/2J mice. Furthermore, the ACAID group exhibited an augmented expression of Treg cells.

Conclusions

Dispersion of pigment particles in the anterior chamber of the eye enhances the state of ocular immune privilege by influencing the immunosuppressive microenvironment and inducing more Treg cells to reestablish ACAID.

XEN45 gel stent in the treatment of pigmentary glaucoma: A two-year follow-up

PURPOSE

To investigate safety and efficacy of the XEN gel stent in patients with pigmentary glaucoma (PG).

METHODS

A retrospective analysis of 26 eyes of 19 patients with PG undergoing XEN gel stent implantation was performed. Best-corrected visual acuity, intraocular pressure (IOP), and number of antiglaucoma medications were analyzed preoperatively, and at 2 weeks and 3, 6, 12, and 24 months after surgery. Success, needling, and complications were analyzed. Complete success was defined as an IOP reduction of >20% and achieving a target IOP of ≤18, ≤15, or ≤12 mmHg without antiglaucoma medication. Qualified success was indicated if the IOP target was reached with or without medication.

RESULTS

Mean IOP decreased significantly from 27.6 ± 14.3 (standard deviation, SD) mmHg to 14.3 ± 4.6 mmHg after one year (p < 0.001) and 15.1 ± 2.7 mmHg (p < 0.001) after two years. The median number of hypotensive drugs declined significantly from 4 (range: 3-5) to 0 (0-2) and 0 (0-3) after one and two years, respectively. After two years, complete success with an IOP of ≤18 mmHg and ≤15 mmHg was achieved in 73.1% and 61.5%, respectively. Half of the eyes required needling after a median time of 8 months (0.5-34 months). No sight-threatening complications were observed.

CONCLUSION

The XEN gel stent is a safe and effective surgical treatment option for PG. Needling is an important part of the procedure and should be communicated preoperatively to the patients.