Low-dose repeated exposure to chemical surfactant impairs corneal epithelium: When personal cleaning products entering the eye

Chitosan-based thermosensitive hydrogel with long-term release of murine nerve growth factor for neurotrophic keratopathy

Neurotrophic keratopathy is a persistent defect of the corneal epithelium, with or without stromal ulceration, due to corneal nerve deficiency caused by a variety of etiologies. The treatment options for neurotrophic keratopathy are limited. In this study, an ophthalmic solution was constructed from a chitosan-based thermosensitive hydrogel with long-term release of murine nerve growth factor (CTH-mNGF). Its effectiveness was evaluated in corneal denervation (CD) mice and patients with neurotrophic keratopathy. In the preclinical setting, CTH-mNGF was assessed in a murine corneal denervation model. CTH-mNGF was transparent, thermosensitive, and ensured sustained release of mNGF for over 20 hours on the ocular surface, maintaining the local mNGF concentration around 1300 pg/mL in vivo. Corneal denervation mice treated with CTH-mNGF for 10 days showed a significant increase in corneal nerve area and total corneal nerve length compared with non-treated and CTH treated mice. A subsequent clinical trial of CTH-mNGF was conducted in patients with stage 2 or 3 neurotrophic keratopathy. Patients received topical CTH-mNGF twice daily for 8 weeks. Fluorescein sodium images, Schirmer's test, intraocular pressure, Cochet-Bonnet corneal perception test, and best corrected visual acuity were evaluated. In total, six patients (total of seven eyes) diagnosed with neurotrophic keratopathy were enrolled. After 8 weeks of CTH-mNGF treatment, all participants showed a decreased area of corneal epithelial defect, as stained by fluorescence. Overall, six out of seven eyes had fluorescence staining scores < 5. Moreover, best corrected visual acuity, intraocular pressure, Schirmer's test and Cochet-Bonnet corneal perception test results showed no significant improvement. An increase in corneal nerve density was observed by in vivo confocal microscopy after 8 weeks of CTH-mNGF treatment in three out of seven eyes. This study demonstrates that CTH-mNGF is transparent, thermosensitive, and has sustained-release properties. Its effectiveness in healing corneal epithelial defects in all eyes with neurotrophic keratopathy suggests CTH-mNGF has promising application prospects in the treatment of neurotrophic keratopathy, being convenient and cost effective.

Integrated analysis of murine cornea identifies JAK/STAT signaling pathway upregulated specifically in female Vitamin A Deficient mice

The Keratoconus (KC) is a corneal ectatic disease with unclear etiology. There are increasing studies that reported its association with a variety of inflammatory mechanisms. Vitamin A(VA) is an important nutrient related to inflammation regulation, and its deficiency may cause abnormalities of the ocular surface. However, the proportion of Vitamin A deficiency(VAD) was found surprisingly high among KC patients in our clinic practice. The aim of this study is to explore the effects of VAD on the transcriptome of corneas with the help of the VAD murine model and transcriptomics techniques. Blood samples of KC patients and non-KC controls (NC) were collected and the serum VA concentrations were measured and analyzed. A total of 52 NC and 39 KC were enrolled and the comparison of serum VA showed that the proportion of VAD in KC patients was 48.7% versus 1.9% in NC group. The further analysis of gender differences showed the proportion of VAD in female KC was 88.9% versus 36.7% in KC male patients. To explore the influence of VAD on cornea, the VAD mice fed with VAD diets were used. The RNA sequencing was employed to compare the corneal transcriptomic characteristics between the VAD female mice, NC female mice, VAD male mice and NC male mice. The transcriptome analysis revealed that the upregulated differential genes were mainly enriched in the immune response related pathways in VAD female mice versus NC female mice, especially the genes of JAK-STAT signaling pathway. The downstream molecules of JAK-STAT pathway were also significant after corneal mechanical scratching in female VAD mice. While, the differential genes between VAD male mice and NC male mice were estrogen signaling pathway instead of JAK-STAT pathway. This study indicates that VAD affects the transcriptomics of murine cornea with gender differences, which specifically affects the inflammatory status of the female murine cornea.

Evaluation of the Effects of Pterygium and Aging on Limbal Structure Using Optical Coherence Tomography

Previous studies suggest that regions of corneal limbus may possess structural differences. We aimed to investigate the limbal changes associated with pterygium and aging via optical coherence tomography (OCT). Palisades of Vogt epithelial thickness (POV-ET) and Bowman’s membrane epithelial thickness (BM-ET) were measured at the nasal, temporal, superior, and inferior quadrants of patients with pterygium and healthy subjects of different ages. Values were expressed as a ratio that functioned as an index used to evaluate the change of limbus. Ratio values determined for quadrants of the corneal limbus were correlated highly in young healthy subjects. Further, parameter values were significantly greater than those of elder healthy subjects. In young subjects, the temporal and superior quadrants of patients with pterygium were significantly lower than those of healthy subjects. Temporal and superior quadrants of elder pterygium patients affected by both pterygium and age were significantly lower than those of healthy subjects; however, the inferior quadrant of elderly pterygium patients was significantly higher than that of age-matched healthy subjects. Our findings revealed that the thickness of limbal epithelium was negatively correlated with age, while pterygium led to the thinning of the temporal and superior limbal epithelium and inferior limbal epithelial thickening.