A biomarker is a parameter that can objectively be measured and evaluated as an indicator of either normal or pathologic processes, or of a response to therapeutic intervention. Biomarkers can change qualitatively (mutation/s) or quantitatively (expression level). The known mutations are involved in a negligible minority of glaucoma patients. Therefore, quantitative approaches comparing expression levels are currently under our consideration in terms of potential diagnostic purposes in glaucoma. The following molecular pathways have been shown to be affected by glaucoma pathology: stress response, apoptosis, DNA-repair, cell adhesion, tissue remodeling, transcription regulation, multi-drug resistance, and energy metabolism. Furthermore, circulating leukocytes of glaucoma patients demonstrate some constant alterations in expression patterns. Our ultimate goal is the application of such information for diagnostic and potentially even for screening purposes. New technologies such as disease proteomics and transcriptomics open new perspectives for the development of rapid molecular diagnostics and follow-up in glaucoma.