What Is in the Glaucoma Test Drops?

During an eye exam, your eye doctor will test the pressure inside your eyes. Increased eye pressure is a risk factor for the development of glaucoma, a disease where the optic nerve is damaged, causing vision loss. Sometimes, the test performed will entail the use of an eyedrop to measure the pressure.

Eye Pressure

• Eye pressure is not the same thing as blood pressure. The fluid-called aqueous humor-inside of the eye is constantly created and drained, and the rate of creation and drainage of the aqueous humor determines the pressure inside of the eye.

Measurements of Eye Pressure

• Your eye doctor will measure your eye pressure using one of a number of methods. The two most common methods are Non-Contact Tonometry (NCT, also known as the air puff test) and Goldmann Tonometry. Goldmann Tonometry involves the use of an eyedrop which numbs the eye, as well as a blue-lighted filter mounted on the slit lamp microscope.

Goldmann Tonometry Eyedrops

• The eyedrops used for Goldmann tonometry are most commonly known by their trade name, Fluress. The two active elements of Fluress are benoxinate, which is a numbing agent much like Novocaine, and fluorescein, which is yellow and glows bright green under the blue light.

Effect of Fluorescein and Benoxinate

• The Fluress drop will sting for 5-10 second upon instillation and then numb your eye for about 15 minutes. It will also make the eye appear yellow for this amount of time as well. Do not wipe your eye on your clothing, as fluorescein is very difficult to get out of fabrics. Your eye doctor will put a blue glowing probe next to your eye in order to measure your eye pressure while the Fluress is in the eye.

Reactions to Fluress

• Rarely, individuals will have a reaction to one of the ingredients in the eyedrop which will cause irritation lasting for a few hours or inflammation to the front of the eye. Other reactions include an odd taste in the back of the throat.