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How Eye Drops are Used to Treat Ocular Health Conditions

Series No. 1: How Eye Drops are Used to Treat Ocular Health Conditions

From calming dry eye irritation to delivering vision-saving medications, eye drops can vary in use and type. CU assistant professor Kaleb Abbott, OD, MS, FAAO, explains how eye drops work and what patients should know.

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Written by Kara Mason on April 29, 2024

The number of people in the United States using eye drops once or more per day increased nearly 10% from 2011 to 2020. Experts expect this number to continue growing as more Americans age and develop ocular conditions treated with eye drops.

“Although not every eye disease is best treated with an eye drop, eye drops do serve an important role in treating many conditions,” explains Kaleb Abbott, OD, MS, FAAO, assistant professor of ophthalmology at the University of Colorado School of Medicine.

"One of the key factors determining the effectiveness of eye drops for specific conditions is their ability to reach the targeted area of the eye requiring the medication," he adds. "Eye drops are generally less effective for treating retinal conditions located at the back of the eye compared to those affecting the front, such as corneal diseases. This is why eye drops are less commonly used in the treatment of retinal disorders."

This means that people who experience dry eye, who are often advised to use over-the-counter lubricating eye drops, or are diagnosed with glaucoma, which may require drops to help reduce intraocular pressure (IOP), may use eye drops, but people experiencing retinopathy are more likely to need injections or surgery.

What makes eye drops an effective treatment

Eye drops typically contain certain ingredients that make the medication absorbent and useful in treating some ocular conditions, but there is sometimes a flip side.

“Sometimes, we don't intend for the medication to penetrate into the eye, yet it still does,” Abbott says. “For instance, we oftentimes use corticosteroids in the treatment of corneal conditions and dry eye. However, a common side effect is that the steroid can penetrate into the eye, potentially leading to cataracts or increased IOP.”

READ MORE: How ophthalmologists are overcoming challenges with eye drops

Eye drops may be prescribed by an optometrist or ophthalmologist, but there are also over-the-counter eye drops that can be helpful in addressing dry eye symptoms. Over-the-counter eye drops most commonly found in grocery stores and pharmacies are “essentially re-wetting” drops, Abbott says, and they exist in varying forms.

“For example, if you have a deficiency in the lipid portion of your tear film, often associated with meibomian gland dysfunction, using an over-the-counter artificial tear that contains lipids or oils can be beneficial. These eye drops can help replace the oils that are lacking in your tear film,” he says. “There are also other artificial tears, which contain certain ingredients such as hyaluronic acid, which have wound healing properties that may help your cornea recover from any epithelial damage.”

Considering health and safety

Eye drops – both prescription and over-the-counter – can either have preservatives or be preservative-free. Preservatives serve to prevent bacteria and fungi from getting into the bottle and possibly causing an eye infection. Preservatives also extend the shelf life of a bottle, thereby reducing waste and saving patients money.

However, sometimes this preservative can aggravate the cornea and exacerbate symptoms, like dry eye.

“Due to the irritating effects of preservatives, many eye drops are now available in preservative-free formulations,” Abbott says. “While preservative-free eye drops are beneficial in minimizing eye discomfort, they also increase the risk of bacterial and microbial contamination, which can lead to infections.”

Preservative-free drops, especially those that are prescription, tend to be single-use or include a limited number of doses to avoid contamination. Even so, it’s important to practice good hygiene with both types. Avoid touching the tip of the dropper to the eye, eyelids, and eyelashes and make sure to properly close the cap after use. It is also imperative to carefully follow any instructions and to discard the bottle when expired.

There are currently several over-the-counter eye drop products that the U.S. Food and Drug Administration advises consumers not to buy due to varying concerns, including potential risk of eye infections that “could result in partial vision loss or blindness.”

Some of the products have been recalled after FDA investigators discovered unsanitary conditions at the factories where the products are made. To make matters worse, the agency is also warning consumers about contaminated “copycat eyedrops.” 

Abbott says it’s important to buy eye drops from a reputable retailer – avoid online shops where it’s unclear where the eye drops are sourced from – and consult the FDA’s recall list and an eye doctor if needed.

Evolving eye drop use

Like other medications, eye drops may come with side effects for some users. They can also be difficult for some people to administer.

These challenges are giving way to new developments in eye drop innovation, including aids that make the medications physically easier to use and devices that administer medication without the need for drops that may need to be administered several times per day.

READ MORE: Finding new uses for eye drops

“Compliance can be a big barrier to effectiveness,” Abbott says. “Fortunately, we’re now starting to see drops with fewer side effects and even alternatives to eye drops – such as simple laser procedures or minor surgeries. These new options are especially beneficial in managing ocular conditions where eye drops cause significant irritation, such as with glaucoma  eye drops, or when patients find it challenging to manage the sheer number of eye drops required for their condition. The treatment landscape is constantly evolving, and options are continually improving.”

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Kaleb Abbott, OD, MS, FAAO