Which is a device used to estimate intraocular pressure (IOP)?

a. A corneal trephine
b. A Geissen eye ruler
c. An air-puff device
d. A phacoemulsifier to measure fluid pressure

ANS: C
IOP is estimated using one of three devices: (1) an air-puff device, (2) a Schiotz tonometer, or (3) an application tonometer. A phacoemulsifier is used to aspirate and break up a cataract.