Why We Check Intraocular Pressure

At Carolina Ophthalmology, we check intraocular pressure (IOP) at all regular eye exams. Checking IOP is a very important way to screen for Glaucoma.

Glaucoma is a chronic disease that affects both eyes, and is the second commonest form of blindness, affecting about 1.6 million people in the United States. Known as the “silent thief of sight,” glaucoma can cause slow, painless, progressive loss of vision. Untreated, high IOP damages the optic nerve and causes vision loss. Many patients experiencing slow loss of peripheral vision don’t notice that it’s happening, and once that damage has occurred it cannot be undone. To read more about Glaucoma, click here.

Due to the lack of noticeable symptoms, early detection through routine screenings is important. This preventative measure allows for early diagnosis and treatment before irreversible damage occurs.

Checking IOP is one way to screen for Glaucoma, and is done along with a dilated exam so the doctor can look at the optic nerve, photographs of the optic nerve, and a visual field test to determine if vision loss has occurred.

There are many ways to check a patient’s IOP, including the dreaded puff-of-air test. We use a more accurate, less terrible test called applanation tonometry (blue-light test). This test involves a Goldmann Tonometer attached to a slit lamp which measures the force required to flatten (applanate) a small segment of the central cornea.

First, the technician will put a drop into your eye that is a numbing agent mixed with fluorescein.  The eye is completely numbed and the patient does not feel the prism touch his or her eye. The fluorescein in the drop causes the eye to glow yellow under the blue light of the tonometer. Next, the technician looks through the instrument and adjusts the pressure of the applanator until it matches the pressure inside the eye. This number is the patient’s IOP.

Most normal eyes have IOP between 10 and 20. However, some eyes cannot tolerate even these normal pressures, and others can have higher pressures than these without damage. Patients with high IOP, or with a family history of Glaucoma, should be closely monitored. Due to the damaging effects of Glaucoma, early detection and effective control of IOP through prescription drops is vital to preserving vision.

Call us today to schedule an eye exam and have your IOP checked at 919.967.4836.