What different eye drop cap colors mean

Eye drop caps are color-coded to make it easier for eye doctors to talk to patients about eye medications and to prevent patient mistakes. Eye drop caps are color-coded based on the type of eye medication in the bottle.

Talk with your eye doctor about prescription eye drop cap colors, what they mean and how to apply eye drops to your eyes.

Both dark blue and yellow eye drop caps are used for medications that contain beta blockers. These eye drops are often used to treat glaucoma. A yellow cap is used for beta blockers. A dark blue cap is used for beta blocker combinations: eye drops that combine a beta blocker with another type of medication.

Beta blockers for glaucoma reduce pressure in the eye, called intraocular pressure (IOP). They work by lowering the amount of fluid, or aqueous humor, in the eye. This fluid provides nourishment to the eye and helps maintain healthy eye pressure.

Gray eye drop caps are used for ophthalmic nonsteroidal anti-inflammatory drugs (NSAIDs). These eye drops decrease pain and inflammation in the eye. They are often used to treat eye symptoms following surgery, such as cataract surgery, LASIK and other types of laser eye surgery for vision correction.

A topical NSAID can reduce redness, itching, swelling and other symptoms caused by inflammation from eye surgery.

Pink eye drop caps are used for steroidal anti-inflammatory medications. These eye drops are often used to treat inflammation from conjunctivitis, iritis, uveitis and other inflammatory eye conditions. Steroid eye drops also may be used to treat swelling that occurs after eye surgery.

A steroidal anti-inflammatory eye medication can reduce inflammation and irritation in the eye.

Dark green eye drop caps are used for miotics, which constrict the pupil. These eye drops were used in the past to lower high eye pressure in primary angle-closure glaucoma, though other treatments are now used. Miotics can also be used to reduce issues with glare after eye surgery. An eye doctor may also use miotic drops to help diagnose a pupil problem such as Adie's tonic pupil.

Miotics bind to certain receptors in the eye, and affect the eye by different mechanisms.

Olive green eye drop caps are used for anti-inflammatory immunomodulators. These eye drops may be used to treat uveitis and eye conditions caused by autoimmune conditions such as rheumatoid arthritis and ankylosing spondylitis.

Anti-inflammatory immunomodulators suppress immune responses in different ways to control inflammation in the eyes. They may be used for some long-term eye conditions after inflammation is initially controlled with steroids.

Orange eye drop caps are used for carbonic anhydrase inhibitors often used to treat primary open-angle glaucoma (POAG). This is the most common type of glaucoma.

Carbonic anhydrase inhibitors work by lowering the amount of aqueous humor production. This fluid provides nourishment to the eye and helps maintain healthy eye pressure. Having less fluid in the eye lowers the eye pressure to a healthy level. These medicines may be used along with other types of glaucoma eye drops.

Purple eye drop caps are used for adrenergic agonists, and light green caps are used for adrenergic agonist combinations. These types of eye drops are used to treat high eye pressure caused by glaucoma or eye surgery.

Adrenergic agonists lower eye pressure by lowering the amount of fluid made in the eyes, and in some cases, increasing the outflow as well.

Red eye drop caps are used for cycloplegics and mydriatics. These types of medications are commonly used by eye doctors to dilate the pupil in order to examine the back of the eye during a routine eye exam.

Cycloplegics that are long-lasting may also be used to manage pain from eye injuries like corneal abrasions. They can also lessen inflammation in patients with inflammatory eye conditions such as uveitis.

Cycloplegics can have mydriatic effects, meaning that they relax the pupil. This can be useful during a routine eye exam or to help an eye doctor diagnose Horner's syndrome and other conditions that affect the pupil.

Low doses of a type of cycloplegic, called atropine, have been shown in some studies to slow the progression of myopia in children.

READ MORE: A guide to atropine eye drops for myopia control

Tan eye drop caps are used for anti-infectives, also known as antimicrobials. These medications may include antibacterial, antifungal or antiviral eye drops.

Anti-infectives prevent or fight eye infections caused by bacteria, viruses or fungi. Among other conditions, they may be used to treat conjunctivitis (pink eye), corneal ulcers, and herpetic keratitis caused by an eye infection.

These eye drops may also be given before, during and after eye surgery to prevent infection.

Turquoise eye drop caps are used for prostaglandin analogues (PGAs), one of the top choices for treating open-angle glaucoma. They lower eye pressure by increasing aqueous outflow. PGAs may be used alone or with other types of glaucoma eye drops.

A topical anesthetic, such as proparacaine, has a white cap. Generic eye drops or drops formulated by a compound pharmacy may also have a white cap. White eye drop caps may also be used for over-the-counter eye drops you can buy without a prescription.

Common OTC eye drops may include artificial tears and drops used to reduce redness. These non-prescription eye drops may provide relief for allergies, eye itchiness or irritation, red eyes and dry eyes.

But keep in mind that OTC eye drops aren't officially part of the color coding system, so manufacturers may choose to use a different color cap.

If you have any questions about your prescription or over-the-counter eye drops, ask your eye doctor. Talking to your eye doctor about your eye drops and how to use them will help ensure you're taking the medications the right way. It may also help avoid mix-ups and mistakes.