An eye-mountable device includes a hydrogel material. By drying the hydrogel material of the eye-mountable device, ethylene oxide may be used to sterilize the eye-mountable device. Such a sterilization method can be employed to sterilize the eye-mountable device when the eye-mountable device includes electronics, sensors, actuated lenses, or other components that may be damaged by heat, pressure, radiation, or other conditions used for sterilization. The eye-mountable device may be stored, dry, within a sealed sterile volume of a packaging material. The packaging material may be permeable to ethylene oxide such that the dried eye-mountable device may be sterilized by ethylene oxide after being sealed within the packaging material. The eye-mountable device could take the form of a contact lens, the form of a device configured to be placed against a sclera of an eye beneath an eyelid of the eye, or could take some other form.