Journal of Ocular Pharmacology and Therapeutics

Cetalkonium chloride (CKC) is a cationic agent used in ophthalmical emulsions. Despite its growing application in ocular drug delivery, its safety profile on corneal endothelial cells remains unclear. This study evaluated the in vitro cytotoxic effects of CKC on human corneal endothelial cells (HCEnCs).

HCEnCs were exposed to CKC at concentrations ranging from 0.03125 to 4.0 × 10⁻⁴% (w/v) for 24–72 h. Cell viability was assessed using Cell Counting Kit-8 and lactate dehydrogenase (LDH) assays. Live/dead cell staining was performed for morphological confirmation. Reactive oxygen species (ROS) production and mitochondrial function were evaluated using DCFDA and MitoTracker assays. Western blot analysis was conducted to examine CKC-induced changes in cell survival pathways, including mammalian target of rapamycin (mTOR), protein kinase B (Akt), extracellular signal-regulated kinase (ERK), Bcl-2-associated X protein (BAX), and B-cell lymphoma-extra-large (Bcl-xL).

CKC induced dose- and time-dependent cytotoxicity in HCEnCs. Exposure to CKC at concentrations ≥0.25 × 10⁻⁴ % for over 48 h significantly reduced cell viability and increased LDH release and ROS production. At concentrations ≥1.0 × 10⁻⁴ %, cell viability was reduced by more than 50% at both 48 and 72 h. In surviving cells, mitochondria showed minimal structural alterations. CKC exposure inhibited cell survival pathways such as mTOR, Akt, Bcl-xL, and ERK, while the proapoptotic pathway marker BAX was upregulated.

CKC exhibits dose- and time-dependent toxicity in HCEnCs, mediated by oxidative stress and the modulation of survival and apoptotic signaling pathways. However, it is challenging to directly extrapolate laboratory conditions to the clinical setting. Therefore, these findings should be interpreted with caution, particularly in scenarios where direct exposure of the corneal endothelium to CKC-containing formulations is anticipated.

Rho-associated kinase (ROCK) regulates fibrosis and angiogenesis. This study evaluated the effects of the topical ROCK inhibitor HA1077 (fasudil) to attenuate corneal fibrosis and corneal neovascularization (CNV) in vivo.

Primary human corneal stromal fibroblasts (hCSF) and New Zealand White rabbits (n = 12) were used. Corneal fibrosis and CNV in vivo were provoked by alkali injury. Immediately post-injury, eyes received topical balanced salt solution (BSS) or HA1077 (3 nM twice/day for 3 days). Clinical slit-lamp biomicroscopy and stereomicroscopy gauged corneal haze/fibrosis (Fante’s score) and CNV (morphometric score) in live rabbits. Post-euthanasia, H&E, immunofluorescence, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays analyzed α-smooth muscle actin (α-SMA), filamentous actin (F-actin), endoglin, CD11b, and apoptotic cells.

HA1077 treatment to hCSF did not alter viability, morphology, and proliferation ability at 3 nM or lower doses. Topical HA1077 (3 nM) treatment significantly reduced corneal haze/fibrosis (P < 0.0001) and CNV (P < 0.0001) in vivo at days 7 and 14 compared with the corresponding controls. Histological H&E analysis revealed retrieval of overall corneal health with a remarkable decrease in fibrotic (myofibroblasts), angiogenic (neovessels), and immune cell infiltration in rabbit corneas treated with HA1077 than the control corneas. HA1077 therapy significantly reduced α-SMA⁺, F-actin⁺, and endoglin⁺ cells, markers of fibrosis and CNV. Intraocular pressure (IOP) remained within the normal physiological range of eyes with HA1077. TUNEL assay revealed the tolerability of the examined HA1077 regimen in vivo.

The tested HA1077 dosage regimen is effective and tolerable to rabbit eyes in abrogating corneal fibrosis and CNV triggered by alkali injury in vivo without major adverse effects. ROCK inhibition represents a promising therapeutic strategy for vascularized and fibrotic corneal wounds but warrants additional dose–response in vivo studies.

Over the past decades, the prevalence of ocular allergies has increased worldwide. Molecular hydrogen is the lightest chemical element, and in recent years, there have been multiple reports on its therapeutic effects. Animal studies have also reported the effects of hydrogen gas on various models of inflammation and circulatory disorders.

In this study, we investigated the effects of hydrogen gas inhalation in a mouse model of allergic conjunctivitis. Mice were sensitized by intraperitoneal injection of ovalbumin. Local sensitization was performed once daily by instilling ovalbumin in both eyes. Conjunctivitis model mice were challenged with antigens, and eye-scratching behavior induced by antigen stimulation was evaluated. The hydrogen gas exposure group was exposed to hydrogen gas after the antigen challenge. In addition, the same mice were exposed to hydrogen gas after antigen challenge, and the number of eosinophils in the tears was evaluated.

An increase in eye-scratching behavior induced by antigen was observed. Hydrogen gas suppressed the increase in eye-scratching behavior. Moreover, hydrogen gas inhibited the increase in eosinophil count in tears.

Active oxygen has a profound effect on itching and eosinophilic function. Therefore, it is thought that inhalation of hydrogen gas suppresses itching of the eye and the migration of eosinophils into the tissue by removing reactive oxygen species. Inhalation of hydrogen gas suppressed the symptoms of allergic conjunctivitis.

To study the ability of five kinin peptides to relax phenylephrine-contracted bovine posterior ciliary artery (PCA; major retinal blood supplier) and carbachol-contracted ciliary muscle (CM) (involved in accommodation and aqueous humor drainage) in vitro.

Isolated bovine CM strips and PCA rings were mounted in small organ baths and perfused with oxygenated Krebs’ solution containing 3 µM flurbiprofen. The tissues were then contracted with 10 µM carbachol (for CM) and 10 µM phenylephrine (for PCA), and the relaxant effects of kinins (0.3 nM to 10 µM) were determined.

All tested kinin peptides concentration-dependently relaxed precontracted CM and PCA in a biphasic manner. The concentrations of the peptides (BK [bradykinin], Hyp³-BK, Lys-BK, Met-Lys-BK, and Des-Arg⁹-BK) yielding half-maximal relaxation (EC₅₀) of PCA via the high potency receptor site ranged between 0.1 nM and 9.0 nM (n = 5–6). Precontracted PCA relaxation by the same kinins via the low potency receptor site occurred with EC₅₀ values of 39.5–399 nM (n = 5–6). In contrast, EC₅₀ values for these peptides relaxing the precontracted CM strips were 0.25–30 nM (high potency receptor site) and 100–3,000 nM (low potency receptor site) (n = 3–6). Precontracted PCA rings were significantly (generally P < 0.005–0.05) more sensitive to the relaxant activity of the kinin peptides than precontracted CM strips.

The tissue relaxant agonist profile of the kinins in both precontracted CM strips and PCA rings, as judged by the 2-site-fit data, indicated the involvement of both B1- and B2-receptor subtypes.

This retrospective exploratory study examines the visual acuity outcomes following a retinal vasculitis (RV) event possibly associated with intravitreal (IVT) biological drugs using a large ophthalmic registry, to gain a better understanding of RV’s impact on vision in real-world clinical settings.

An ophthalmic registry was used in a retrospective exploratory analysis and focused on subjects who received IVT anti-VEGF and anticomplement therapies. We excluded eyes with RV in the visual acuity analysis that had received more than one IVT biological drug within 2 months before the diagnosis of RV to increase confidence that a single biological drug was possibly associated with the RV event.

A total of 1,998,399 subjects received IVT injections of biological drugs, and 2,115 subjects were diagnosed with RV in at least 1 eye. A total of 436 subjects (531 eyes total) were coded as having RV. There was a 78% increase in eyes that became legally blind (≤20/200 Snellen equivalent) and 46% increase in eyes reading 0 letters (≤count fingers vision) following the RV event.

In the real world, the number of legally blind eyes substantially increased following the RV diagnosis. Given the retrospective and exploratory nature of this study, all interpretations should be made cautiously, including any suggested association between biological therapy and the occurrence of RV, and prospective studies are necessary to confirm these associations. Further research is indicated to improve the safety of biological therapies for retinal diseases and minimize the risk of serious complications such as RV.