This chapter outlines key quantitative measurements used across ophthalmic subspecialties to assess ocular structure and function. In retinal research, parameters such as retinal layer thickness, blood flow velocity, and visual sensitivity guide advancements in imaging, gene therapy, and neurovisual studies. Glaucoma research relies on metrics like intraocular pressure, optic nerve morphology, retinal nerve fiber and ganglion cell layer measurements, and visual field sensitivity to monitor disease progression and treatment response. Corneal studies emphasize measurements including corneal thickness, curvature, and endothelial cell density to evaluate biomechanics, transparency, and regenerative potential. These applied values serve as critical benchmarks for diagnosis, disease monitoring, and innovation in eye care.