Tear Proteomic Approach and Identification of Tear Film Biomarkers with Rigid Gas Permeable Scleral Contact Lens (ScCLs) Wear for Keratoconus

Keratoconus (KC) is a classical non-inflammatory disorder associated with elevated serum levels of IgE, IgG, and IgM [1,2]. Lema et al. [3] have described specific cytokines and protease profiles in patients with keratoconus; and found levels of IL-6, TNF-alpha, and MMP-9 were elevated in keratoconus subjects as compared to normal. The differential expression of tear film proteins such as MMP-1, keratins, and mammaglobin B can be found in keratoconus subjects [4]. Tear fluid has been successfully used as a source of biomarkers in several well-studied eye diseases. Studies performed on tear fluid in patients of keratoconus provided insights into the pathology of the disease and revealed probable prognostic and diagnostic biomarkers for the disease [5]. A multi-omics approach integrating data from proteomics, lipidomics and metabolomics is the need of the hour for studying tear fluid as an important source of biomarkers in keratoconus to lead to effective prognosis and treatment of the disease. Tear fluid is a highly complex chemical and biological mixture containing proteins, peptides, electrolytes, lipids, and metabolites. It is proposed to be a surrogate representative for many eye diseases. It is an integral part of the ocular surface and represents the extracellular matrix for ocular surface epithelial cells [4,6]. Nano-mass Spectrometry and Liquid Chromatography were used in tear analysis, including analysis in proteomics, metabolomics, and lipidomics. Dry eye and meibomian gland dysfunction diseases involve the disruption of the lacrimal functional unit, resulting in symptoms of discomfort, visual disturbance, and tear film instability. These illnesses may exist independently as either symptomatic or asymptomatic disorders. However, they are frequently found in the same patient. The progression of these diseases typically leads to alterations in the tear film, tear hyperosmolarity, and the secretion of inflammatory mediators into the tears, initiated by cytokine release and metalloproteinase activation. Ocular dryness disorders also promote squamous metaplasia, mainly as a consequence of inflammation, whose severity can be used for grading different diseases affecting the ocular surface. In this study, we explored the efficacy of Rigid Gas Permeable Scleral Contact Lens in keratoconus regarding the expression of inflammatory Mediators.