Saturday, March 5, 2022

Best Active Ingredients of Eye Drops for Dry Eyes

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In today's article, I would like to talk to you about the science behind the ingredients in artificial tears. These are the over-the-counter eye drops for treating dry eye disease. This post will help you to understand the differences between different dry eye drop ingredients and will help you choose the artificial tears that work best for you.

eye-drops-active-ingredients-for-dry-eyes

Without further ado, let's talk about the ingredients in artificial tears. The ingredients of artificial tears can be categorized into three groups:
  • Active Ingredients
  • Inactive Ingredients
  • Preservatives

1. Active Ingredients

The active ingredients are the agents that have been approved by the FDA to be used in artificial tears to provide lubrication to the eye. There are three main categories of active ingredients in artificial tears.
  • Astringent
  • Demulcent
  • Emollient

Astringent

The most commonly used ophthalmic astringent is zinc sulfate. Two common brands of dry eye drops that contain zinc sulfate are Clear eyes drop made by prestige consumer healthcare and Visine made by johnson & johnson.

Zinc sulfate can help reduce the burning and itching sensation from exposure to the pollutants in the air by reducing the mucus on the surface of the eye. So it can help reduce some allergy symptoms but zinc sulfate is not very effective in lubricating the eye compared to other active ingredients. So it is not a top active ingredient in artificial tears that I recommend for my patients to treat their dry eye disease.

Demulcent

The second group of active ingredients is called demulcent. This is the main ingredient in artificial tears which determines the consistency and thickness of the drop. Demulcents are typically mucoprotective agents. They reduce inflammation and irritation of the mucus membrane of the eyes and hold moisture to lubricate the surface of the eye.

They act on both the aqueous and the mucin layers of the tear film. There are a few common demulcents used by different brands of artificial tears. Carboxymethyl cellulose sodium (CMC) is the main demulcent used in the Refresh brand artificial tears made by Allergan. Systane brand of artificial tears made by Alcon typically contains polyethylene glycol or propylene glycol as their demulcent.

The other commonly used demulcent agent is hydroxypropyl methylcellulose (HPMC). It is the demulcent used in GenTeal brand artificial tears made by Alcon. Variation in the concentration of the demulcent such as CMC affects the consistency and the viscosity of the artificial tears.

For example, Refresh Optive gel drop contains 1.0% CMC which is double the concentration of CMC in the regular refresh optive eye drop. This allows the gel drop to provide a longer-lasting lubricating effect.

However, the higher concentration of the demulcent used increases the thickness of the artificial tears. This will require more blinking action by the eyelid to spread the demulcent polymer over the surface of the eye. Therefore if you use a gel eye drop you may notice it takes a little bit longer and more blinks to clear your vision after you put in the eye drop.

Emollient

The third category of active ingredients is emollient. An emollient is usually fat or oil providing a long-lasting lubricating effect, and the eye drop which contains emollients tend to be thicker and take longer to clear up. So the liquid formulations of artificial tears typically do not contain a large number of emollients.

For example, mineral oil is a commonly used emollient and is intended to replace and thicken the lipid layer of the tear film in order to improve the stability of the tears and slow down the evaporation of the tears.

More commonly emollients are found in ointment formulations of artificial tears such as Refresh PM and Systane Nightime eye ointments. These formulations are more frequently used before bedtime and reserved for moderate to severe dry eye disease.

Some newer liquid formulations of artificial tears target all three layers of the tear film including the lipid layer, which often contain a small amount of emollient to provide a longer-lasting lubricating effect to the eye.

Artificial tears which contain emollients are a little bit thicker. So after you put in the drop make sure you blink a few times to spread out the eye drop across the surface of the eye. You may notice the vision is a little bit blurry and it may take a few blinks to clear up your vision. If you want to know what eye drops should not use for dry eyes. Click here

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