A system for measuring intraocular pressure in an eye of a patient includes a sensor configured to be positioned in the eye of the patient. The sensor includes a sealed cavity, and a flexible membrane sealing a distal end of the sealed cavity, the flexible membrane configured to deflect responsive to the intraocular pressure in the eye of the patient. The system includes a detection device configured to be positioned external to the eye of the patient and optically coupled to the sensor, the detection device configured to detect an indication of change in length of the sealed cavity resulting from deflection of the flexible membrane.