Abstract: Systems, devices, and methods for measuring intraocular pressure of the eye are disclosed. More particularly, the improved systems, devices, and methods enable the use of applanation tonometry and tonography to make such measurements using a portable, handheld applanation device. The applanation devices apply a constant fixed force to the surface of the eye. The resulting applanation mire can be captured by an image-capturing device and the intraocular pressure can be calculated using a provided algorithm based on the applanation mire and a known reference with respect to the eye.