Glaucoma eye condition and Dry Eye Disease

What is glaucoma?

Glaucoma is an eye condition in which the optic nerve that transmits vision signal from the retina to the brain gets damaged. This results from the increased pressure inside the eye brought about by accumulation of fluid due to overproduction or blockage. Patients with glaucoma can lose their vision if not diagnosed and treated promptly. It can occur in all ages but is more common in older adults.¹

There are four major types of glaucoma:¹

Primary open-angle glaucoma
The most common type of glaucoma (90% of the cases) which has a particularly high prevalence in Asian people.2 The first symptoms are very subtle and people may not notice them. At the early stages, peripheral vision, the edge of your sight, might be affected. The condition usually happens on both eyes.³

Acute angle-closure glaucoma
An emergency in which the pressure inside the eye elevates quickly resulted from an obstruction of the ocular aqueous outflow. Patients may feel headache, eye pain and blurred vision on one side of the eyes and a sight of a dime rainbow circle when looking at bright lights.⁴

Secondary glaucoma
Caused by other underlying eye conditions or medical disorder, such as eye inflammation, eye injury, diabetes or long-term steroid eyedrop treatment.^{5, 6}

Childhood (congenital) glaucoma
A rare type that occurs in very young children which can be inherited, caused by an abnormality of the eye’s drainage system.⁷

The cause of glaucoma is unknown, but there are certain factors that increase the risk:

Age
About 1 percent people in their 40s have glaucoma, the rate rises to 10 percent for those over 80s.⁸

Ethnicity
African, Caribbean and Asian origin are more likely to develop glaucoma.⁹

Family history
Parents or siblings having glaucoma may increase the risk of having the same condition.¹⁰

Other medical conditions such as hypertension, diabetes or obesity.¹⁰

Is there a link between glaucoma and Dry Eye Disease (DED)?

Glaucoma and dry eye disease often coexist. Studies have found that about 40-60 percent of people with glaucoma also have dry eyes.¹¹

One of the reasons is that the high-risk group for DED and glaucoma is often the same. For example, both of these conditions are more common in older adults and people with hypertension, diabetes or obesity.^11,12

Besides, DED can also be caused by the use of eye drops prescribed for glaucoma treatment. These medications often contain benzalkonium chloride (BAK), a preservative that can affect the cells on the surface of the eye and lead to dry eyes. Some researchers believe that BAK can cause damage to the cells producing mucin, a mucous protein that keeps the tear film stable and prevents the eye surface from dryness.^{13, 14}

How to treat both glaucoma and DED?

Simultaneously treating DED and glaucoma might be challenging for both the patient and the doctor. The treatment of DED plays an essential role in preserving the long-term health of the eye surface as well as providing comfort to the patient, which often focuses on maintaining an adequate tear film on the surface of the eye. However, treating glaucoma will be prioritized because glaucoma is a disease that, if not treated promptly and properly, can lead to severe visual impairment or blindness. For patients with concomitant glaucoma and DED, depending on the cause as well as the condition of the dryness, a modification of treatment approach can be done by their doctors:

Reducing the preservative exposure

Switching to preservative-free glaucoma eye drops
using single‐dose preservative‐free medication can avoid the dry eye effect caused by BAK.^{14, 15} However, not all topical glaucoma medications are available in preservative‐free formulation. In addition, treatment expenses should be put into consideration since the single‐dose options are much more expensive, not to mention that patients with poor dexterity may have difficulty handling the small containers.^{14, 16}

Opting for combination eye drops
Taking products combining two or more agents means fewer drops and less preservatives instilled on the eye.¹⁴

Laser surgery
Option for a first-line treatment in newly diagnosed glaucoma. Laser can be used to facilitate the aqueous outflow of the eye and reduce the need of eye drops in the management of glaucoma. But this is not a permanent cure for glaucoma since the effect of the operation can decrease over time.¹⁷

Treating the DED

Using artificial tears
An initial therapy for those who are suffering from mild DED. Artificial tears share the same properties as natural tears. This can be considered a “functional food” for the dry eyes which act as a moisturizer for the ocular surface.¹⁷

Using lubricants
Moisturizing gels or ointments are alternative remedies for DED. Ointment will bring comfort to the eyes thanks to its lubricating ability. They are effective when used for a longer period of time and are often used during sleep.¹⁷

Lid cleaning
A simple way to alleviate the dry eye condition. There are glands in the eyelids that secrete oil to reduce tear evaporation. Eye inflammation can cause blockage of these glands and anti-glaucoma eye drops containing active ingredient similar to prostaglandin can worsen the condition. Lid massage and cleaning the edge of the eye daily will keep these gland healthy.¹⁷

Punctal plug insertion
A technique to treat DED by using a plug which is inserted into the tear duct opening in the corner of the eye, where tears usually drain away to the back of the nose and throat. This will keep the eyes lubricated since tears are trapped on the eye surface.¹⁸