Changes in the elemental composition of aqueous humour outflow pathways in primary open-angle glaucoma

PURPOSE: There are two primary aims of this study:

1. To perform a comparative chemical analysis of aqueous humour (AH), scleral tissue, and trabecular meshwork in patients with primary open-angle glaucoma (POAG).

2. To evaluate the tissue’s chemical composition at the different POAG stages and with in patients with pseudoexfoliation glaucoma (PEG).

METHODS: The concentration of certain chemical elements — carbon (C), nitrogen (N), oxygen (O), aluminum (Al), calcium (Ca), chlorine (Cl), potassium (K), magnesium (Mg), sodium (Na), phosphorus (P), silicon (Si), sulfur (S) — was determined in the dried AH residue, trabecular meshwork and sclera biopsy samples obtained from patients with POAG (stage I and II), patients with pseudoexfoliation glaucoma (PEG), and patients with POAG without pseudoexfoliation material (PEM). Samples were analyzed using a scanning electron microscope (SEM) EVO LS 10 (“Zeiss”,Germany). The chemical composition study was performed with an energy-dispersive spectrometer (EDS) Oxford-XMAX-50 (“Oxford”,UK) in a low-vacuum mode (70 Pa) with an accelerating voltage of 21.5 kV.

RESULTS: In the case of POAG (stage I and II) patients, there were significant differences in Cl distribution in dried AH residue and Si distribution in the trabecular meshwork. In the case of pseudoexfoliative glaucoma (PEG) and patients with POAG without PEM, there was a difference in the N distribution in dried AH residue, as well as Ca, Cl, and Na distribution in the trabecular meshwork. During scleral tissue comparative chemical analysis, no significant changes in studied elements’ concentration between patient groups were evident.

CONCLUSION: Changes between stage II of POAG and stage III of POAG patient groups may indicate that there is an increase in the electrolyte and acid-base imbalance associated with the progression of the disease. Differences in chemical elements distribution in patients with PEG and in patients with POAG without PEM result from the molecular structure of PEM. The tissue’s water and salt balance and molecular chemical composition alterations provide the following insights for future research in finding the optimal treatment method for patients with all stages and types of glaucoma.

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