Artificial Tears: A Primer

Question 1

What is an ophthalmic astringent and what do we use them for?

Answer 1

A locally acting pharmacologic agent that precipitates protein. This helps clear mucus from the surface of the eye.

Question 2

What is an ophthalmic demulcent and what do we use them for?

Answer 2

An agent (usually water-soluble) that is used to protect and lubricate mucous membranes. Demulcents contain aqueous and are used to treat patients with aqueous deficient dry eye.

Question 3

What is an ophthalmic emollient and what do we use them for?

Answer 3

An agent that is fat/oil-containing. This is used to protect/soften tissues to prevent drying/cracking. Emollients are used to treat evaporative dry eye.

Question 4

What are the permitted indications for demulcents/emollients?

Answer 4

1. Temporary relief of burning/irritation due to dry eye.
2. For temporary relief of discomfort due to minor eye irritation.
3. Protection from further ocular irritation
4. Lubrication to prevent ocular irritation

Question 5

How do artificial tears increase tear retention?

Answer 5

1. Increasing tear viscosity
2. Increasing tear adherence
3. Decreasing tear evaporation
4. Decreasing tear clearance

Question 6

What are three noteworthy demulcents?

Answer 6

1. Polyethylene glycol (PEG)
2. Propylene Glycol (PPG)
3. Glycerin

Question 7

Explain how PEG works.

Answer 7

PEG (Polyethylene Glycol) is a demulcent used in artificial tears. PEG has a high molecular weight and is used to increase the viscosity of the artificial tear. PEG forms a protective layer over mucous membranes that preserve/protect the ocular surface.

Question 8

Explain how PPG works.

Answer 8

PPG (Propylene Glycol) is a demulcent used in artificial tears. PPG works in the same way as PEG but it is also a humectant, which means it can absorb up to 3x its weight in water. This makes it great for increasing the aqueous component of the tears.

Question 9

Explain how Glycerin works.

Answer 9

Glycerin is a demulcent used in artificial tears. Glycerin is also a lubricant and a humectant. In addition to being a demulcent and a humectant, glycerin is also a lubricant. this means it also incorporates a lipid component that reduces tear evaporation.

Question 10

What are some general functions of demulcents?

Answer 10

1. Increase the viscosity of tears
2. Increase the mechanical strength of the tear film
3. Thickening tear film and reducing evaporation

Question 11

What are demulcents?

Answer 11

Demulcents are substances that are used for pain relief in inflamed/irritated mucous membranes, such as the eye. Demulcents are moisturizing?

Question 12

What are emollients?

Answer 12

Fat based agents that are used to soften and protect tissues to prevent cracking/drying. They seal in existing moisture. They do NOT moisturize!

Question 13

What are some functions of emollients?

Answer 13

Lubrication
Contribution to the oil layer of tears
Stabilize lipid tears and increase TBUT
Seal in moisture

Question 14

What is an inactive ingredient?

Answer 14

Inactive ingredients are NOT specified by the FDA, but the inactive ingredients must not interfere with product effectiveness.

Question 15

Why are inactive ingredients added to artificial tears?

Answer 15

1. Help lower viscosity of gelling agents, which prevents them from getting too thick.
2. Protect/promote corneal epithelial healing
3. Increased viscosity when the eye is open
4. Increased water retention

Basically improve the artificial tear and moderates any exaggerated effects from the active ingredients

Question 16

Why are preservatives added to artificial tears?

Answer 16

1. increased shelf life

2. Anti-bacterial properties

Question 17

Why is BAK being replaced by other preservatives?

Answer 17

BAK disrupts epithelial tight junctions, decreasing the integrity of the cornea.

Question 18

Why should you be careful when prescribing a generic artificial tear?

Answer 18

Generic versions only need to match the ACTIVE ingredients that are in brand name tears. This means they can put whatever they want for inactive ingredients. Many choose BAK because it’s cheaper.