Efficacy and safety of microbial transglutaminase-induced scleral stiffening invivo

Scleral collagen cross linkage in progressive myopia

High myopia is often associated with local ectasia and scleral thinning. The progression of myopia depends upon scleral biochemical and biomechanical properties. Scleral thinning is associated with decreased collagen fiber diameter, defective collagen fibrillogenesis, and collagen cross-linking. Reversing these abnormalities may make the sclera tougher and might serve as a treatment option for myopic progression. Collagen cross-linking is a natural process in the cornea and sclera, which makes the structure stiff. Exogenous collagen cross-linkage is artificially induced with the help of external mediators by using light and dark methods. In this systematic review, we discussed existing literature available on the internet on current evidence-based applications of scleral collagen cross-linking (SXL) by using different interventions. In addition, we compared them in tabular form in terms of their technique, mechanisms, cytotoxicity, and the stage of transition from preclinical to clinical development. Furthermore, we discussed the in-vivo technique to evaluate the post-SXL scleral biomechanical property and outcome in the human eye.

Molecular Basis of Transglutaminase-2 and Muscarinic Cholinergic Receptors in Experimental Myopia: A Target for Myopia Treatment

Myopia, a prevalent refractive error disorder worldwide, is characterized by the elongation of the eye, leading to visual abnormalities. Understanding the genetic factors involved in myopia is crucial for developing therapeutic and preventive measures. Unfortunately, only a limited number of genes with well-defined functionality have been associated with myopia. In this study, we found that the homozygous TGM2-deleted gene in mice protected against the development of myopia by slowing down the elongation of the eye. The effectiveness of gene knockdown was confirmed by achieving a 60 percent reduction in TGM-2 transcript levels through the use of TGM-2-specific small interfering RNA (siRNA) in human scleral fibroblasts (SFs). Furthermore, treating normal mouse SFs with various transglutaminase inhibitors led to the down-regulation of TGM-2 expression, with the most significant reduction observed with specific TGM-2 inhibitors. Additionally, the study found that the pharmacological blockade of muscarinic receptors also slowed the progression of myopia in mice, and this effect was accompanied by a decrease in TGM-2 enzyme expression. Specifically, mice with homozygous mAChR5, mAChR1, and/or mAChR4 and knockout mice exhibited higher levels of TGM-2 mRNA compared to mice with homozygous mAChR2 and three knockout mice (fold changes of 5.8, 2.9, 2.4, -2.2, and -4.7, respectively; p < 0.05). These findings strongly suggest that both TGM-2 and muscarinic receptors play central roles in the development of myopia, and blocking these factors could potentially be useful in interfering with the progression of this condition. In conclusion, targeting TGM-2 may have a beneficial effect regarding myopia, and this may also be at least partially be the mechanism of anti-muscarinic drugs in myopia. Further studies should investigate the interaction between TGM-2 and muscarinic receptors, as well as the changes in other extracellular matrix genes associated with growth during the development of myopia.