Choroidal status in angle-closure glaucoma

Glaucoma remains one of the leading causes of irreversible blindness worldwide. Primary angle-closure glaucoma (PACG) is characterized by episodic impairment of aqueous humor outflow and increases in intraocular pressure (IOP), leading to glaucomatous optic neuropathy. Traditionally, in the pathogenesis of PACG the emphasis has been placed on anterior segment anatomy, but in recent years, the role of the posterior segment, including the choroid, has been attracting increasing interest. This review aimed to evaluate, based on the literature, the possible role of choroidal changes in the pathogenesis of PACG by analyzing its morphometric parameters and their association with IOP. We reviewed publications in which choroidal parameters were assessed mainly using optical coherence tomography, including measurements of choroidal thickness and calculation of the choroidal vascularity index (CVI). According to individual studies, choroidal thickness in patients with PACG is significantly greater than in healthy individuals (for example, 355.36 µm vs. 286.08 µm; p<0.05), and is also greater in angle closure than in controls (284.99 µm vs. 250.79 µm; p<0.05). Increased choroidal thickness and/or vascularity has been observed in acute and chronic PACG compared with normal values (p<0.05), with no differences between acute and chronic forms (p>0.05). Several studies highlighted an association between a thicker choroid and uncontrolled IOP on maximal medical therapy (245.57±62.10 µm in controlled IOP and 294.46±51.05 µm in uncontrolled IOP; p<0.01). In a comparative study of primary open-angle glaucoma (POAG) and PACG, CVI was lower in both forms than in healthy eyes (p=0.001 and p=0.005), while the pattern of structural alterations differed between the glaucoma types. Overall, morphometric characteristics of the choroid in PACG are associated with IOP level, supporting the concept that the choroid is involved in the pathogenesis of the disease and justifying further research in this direction.