Glaucoma primarily occurs when there is increased pressure inside the eye due to the blocked drainage and subsequent buildup of a substance called aqueous fluid. Optometrist Elisabeth Hottel likens eye pressure to tire pressure, explaining that just as a tire needs the right amount of air to function properly, the eye needs the right amount of fluid pressure. 

If the pressure is too high, she says, it “pushes back onto the optic nerve, causing vision loss.” The aim of glaucoma treatment is to lower this pressure and prevent further damage. Medicated eye drops are the most frequently prescribed treatments.Here, Dr. Hottel explains how and why glaucoma eye drops work.*

How Different Glaucoma Eye Drops Work

Prostaglandins

Prostaglandins are one of the most commonly prescribed eye drops for glaucoma. They help increase fluid drainage from the eye by relaxing the ciliary body, a ring-shaped muscle with two functions:

• Changing the shape of the lens when your eye focuses,
• Producing a substance called aqueous fluid which nourishes the eye and keeps it inflated by exerting pressure from inside your eye. 

Prostaglandins move fluid through the ciliary body and into the sclera (the white part of the eye), where it then drains into the lymphatic system. 

These drops are effective in significantly lowering eye pressure, making them a first-line treatment. However, They come with unique side effects, however, such as: 

• Increasing your eyelash length, 
• Changing the color of your iris, and (sometimes) 
• Darkening the skin surrounding your eyes.

Beta Blockers 

Beta blockers function differently, Hottel explains, by limiting how much aqueous fluid the eye produces. They have been a staple in glaucoma treatment, either as a first or second-line option, but can cause systemic side effects, including:

• Low blood pressure, 
• Low pulse rate, and 
• Fatigue. 

All of these potential effects make beta blockers a less ideal option for patients with certain heart or respiratory conditions. 

Other Medications

Other medicated drops used to treat glaucoma include:

• Carbonic anhydrase inhibitors, which similarly reduce fluid production but can cause “stinging, burning, and ocular discomfort” when applied, Hotel says.
• Alpha agonists, which serve a dual purpose by both reducing fluid production and increasing fluid outflow. Potential side effects include fatigue, dry mouth, and dry nose.
• Rho kinase inhibitors, a newer type of drop, increase fluid drainage by altering the stiffness of the drainage structure’s cells and reducing adhesions in the eye. Eye pain, the white part of the eye appearing red, and whorl-like patterns in the cornea are potential side effects of these drops.

Combination Treatments 

Often, a single type of drop may not be sufficient to achieve the desired reduction in eye pressure, leading to the use of combination therapies. These can involve using multiple drops targeting different parts of the aqueous production and drainage system. 

Because, as Hottel says, “the more drops you add into the mix, the more it is to keep track of,” combination drops that include two medications in one bottle are available.

Takeaways

Effective glaucoma management with eye drops involves understanding how each type of medication works and balancing the benefits with potential side effects. Since glaucoma is a chronic condition requiring lifelong treatment, it’s crucial to work closely with your healthcare providers to find a treatment plan that works best for you. 

*Hottel, E. [Dr. Elisabeth]. (2023, August 11). Glaucoma Eye Drops: How and Why They Work [Video file]. Retrieved from https://www.youtube.com/watch?v=NlaHuoK4Hqw