Which of the following can be used for self tonometry?

In self tonometry patient himself measures the intraocular pressure. The dynamic contour tonometer represents a potentially new technology for non-invasive and direct intraocular pressure (IOP) measurement, and has been proposed to accurately measure the true IOP irrespective of the corneal thickness. The Perkins tonometer is a type of poable applanation tonometer, which may be useful in children, anesthetised patients who need to lie flat, or patients unable to co-operate with a sitting slit lampexamination, that yields clinical results comparable to the Goldmann. Rebound tonometers determine intraocular pressure by bouncing a small plastic tipped metal probe against the cornea. The device uses an induction coil to magnetise the probe and fire it against the cornea. As the probe bounces against the cornea and back into the device, it creates an induction current from which the intraocular pressure is calculated. The device is simple and easy to use and self-use versions are available. It is poable, does not require the use of eye drops and is paicularly suitable for children and non-cooperative patients. The image above shows rebound tonometer. Diaton tonometer is a handheld device measuring IOP through the eyelid and over the sclera with no contact to the cornea & causing no discomfo to the patient.The pen-like tonometer diaton measures IOP within seconds without the need for anesthesia or sterilization.