[Ocular toxicity of benzalkonium]

Capsanthin from Capsicum annum fruits exerts anti-glaucoma, antioxidant, anti-inflammatory activity, and corneal pro-inflammatory cytokine gene expression in a benzalkonium chloride-induced rat dry eye model

Dry eye disease (DED) is a complex ocular surface inflammatory disease. Its occurrence varies widely over the world, ranging from 5% to 34%. The use of preservatives, specifically benzalkonium chloride, in the ocular drops worsens the DED conditions. Furthermore, the Covid-19 pandemic increased screen time and the use of face masks and shields. As a result, the number of people suffering from dry eye disease (DED) has increased significantly in recent years. The main objective of our study is to find a solution to manage the dry eye disease (DED) preferably from natural source without any adverse events. In this study, the beneficial effects of capsanthin from Capsicum annum (CCA) were evaluated on benzalkonium chloride (BAC)-induced dry eye disease (DED) in Albino Wistar rats. Oral supplementation of CCA resulted in a statistically significant decrease in intraocular pressure (IOP) (p < .0001), increase in tear break-up time (TBUT) (p < .01), decline in Schirmer test results (p < .01), and decrease in corneal surface inflammation (p < .01). Capsanthin ameliorated in reducing oxidative stress by increasing serum antioxidant levels such as glutathione peroxidase (GPX), nitric oxide (NO), and lactoferrin (LTF) and inhibiting matrix metalloproteinases 2 and 9 (MMP2 and MMP9) (p < .0001). Capsanthin treatment significantly inhibited the expression of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), interleukins (IL-2, IL-4, IL-6), and pro-inflammatory mediator, matrix metalloproteinase-9 (MMP9). Furthermore, the lacrimal gland expressed vascular cell adhesion molecule (VCAM-1), and prostaglandin-endoperoxide synthase 2 (PTGS2) was suppressed by CCA treatment. PRACTICAL APPLICATIONS: Benzalkonium chloride (BAC), a preservative widely used in the topical ocular drug delivery system (ODDS), causes undesirable effects such as dry eye disease as well as ameliorating intraocular pressure leading to optical nerve damage and irreversible vision loss. Capsanthin from Capsicum annum (CCA) can be used to treat symptoms related to dry eye disease such as inflammation, eye irritation, visual disturbance, ocular discomfort with potential damage to the ocular surface. The CCA may be beneficial in the treatment of glaucoma, an elevated intraocular pressure. Capsanthin from C. annum can be useful in managing DED by increasing tear break-up time (TBUT), declining in Schirmer test results and decreasing in corneal surface inflammation.

Glaucoma therapy: preservative-free for all?

Preservatives used in topical glaucoma medications have a plethora of well-described toxic effects on the ocular surface. Such ocular toxicity is manifest clinically as ocular surface disease (OSD) and has been confirmed in epidemiologic, prospective clinical trials and studies in which patients are switched from preservative-added to preservative-free topical therapy. Such toxicity has implications not only for tolerability, but also for adherence and persistence with therapy that is known to be poor in glaucoma. Glaucoma medication is now widely available in preservative-free formulations, and the question arises as to which patients should receive preservative-free glaucoma therapy in preference to preservative-added medication. A case can be made for several subpopulations of patients who might particularly benefit from preservative-free medication: patients with existing OSD, older patients, younger adult patients, female patients, pediatric and juvenile patients, patients who work in air-conditioned environments or who use electronic screens frequently, patients with medical risk factors for OSD, patients in whom trabecular surgery may become indicated in the future, contact lens users, perhaps patients with Asian ethnicity and patients with severe or treatment-refractory glaucoma. Whilst arguments could be made for selecting patients for preservative-free medication on the basis of their existing risk of OSD, collectively, these patients form a significant proportion of the glaucoma patient population as a whole and, in the absence of any cost premium or positive indication for preservative-added medication, preservative-free glaucoma medication for all patients seems an appropriate strategy.