Dry Eyes and Glaucoma, what is the connection?

Photo Credit: by Rudy and Peter Skitterians, Pixabay.com

Dry eye syndrome is a condition in which the eyes do not produce enough tears, or the tears evaporate too quickly. Although dry eyes are more commonly experienced by people over 50, any age group can experience dry eye. Glaucoma is a vision threatening disease characterized by optic nerve damage and loss of retinal cells from too high pressure in the eye.

Glaucoma is the second leading cause of blindness in the United States, affecting about 3 million Americans. Dry eye syndrome prevalence is also quite high. This disease affects 50 percent of people over the age of 60. Dry eye and glaucoma share common risk factors such as age and female sex, along with other factors such as environmental exposure and family history.

Many people may be wondering: what is the connection between dry eyes and glaucoma?

Here is the link: Both dry eyes and glaucoma occur predominantly in the older population. About 40-50 % of glaucoma patients also have dry eyes. People with glaucoma are at higher risk for dry eyes because some glaucoma medications can even worsen the condition of the eye surfaces causing dry eye.

Furthermore, a common preservative in glaucoma medications, benzalkonium chloride is known to damage the surface of the eye which results in dry eyes. Thus, it is recommended to use preservative-free eye drops in glaucoma patients that also have dry eye. In addition, certain classes of drugs which are known to cause dry eyes have also been identified as causal agents for glaucoma.

DRY EYE SYNDROME

The most common symptom of dry eyes are blurred vision, pain and irritation to the eye, particularly when blinking or moving their eyes. Sometimes the eye will have a gritty or sandy feeling. One can also experience a foreign body sensation, especially when tired or following prolonged computer use.

Normally, when we blink, a layer of tear forms over our eyes. Its basic functions include:

(1) Protecting the eyes from infections

(2) Getting rid of irritants like dust, dirt, pollens and allergens

(3) Keeping the eyes wet and smooth

(4) Helps to focus light for clearer vision

Dry eyes, if not properly treated, may result in damage to the eyes and significantly reduced vision.

Common causes of decreased quality and reduction in quantity of tears includes:

• Certain types of medications such as cold and allergy medicines, mood control drugs and high blood pressure medications.

• Use of contact lenses

• Nerve damage from laser eye surgery or medical conditions like diabetes

• Some conditions of the immune system like the Sjogren’s syndrome and allergic eye conditions

• Increase in age

• Drastic change in weather and atmospheric conditions

• Decreased frequency of blinking

• Eye drop preservatives

• Disorders of the tear duct

DRY EYE TREATMENT

The use of lubricating eyedrops is the main step. Most of these are available over the counter and needs no prescription. While this will relieve the symptoms of dry eyes, its does not solve the underlying cause of the dry eyes. Examples include products like Artificial tears and Systane. A preservative free option is better for frequent and prolonged use. If dry eye is not adequately resolved with over-the-counter medications, further evaluation by a professional may be needed.

If dry eye is more severe, a prescription drug is usually much more effective than its over-the-counter counterpart. Examples include cyclosporin (Restasis) and lifitegrast (Xiidra). They work by increasing the volume of tear production and reduce ocular surface inflammation.

GLAUCOMA

At the initial stages, glaucoma often narrows down the field of vision such that one cannot see things from the side, i.e. gradual loss of peripheral vision. Without treatment, the condition progresses and may lead to complete blindness.

Elevated pressure in the eye, also known as ocular hypertension, is the most important and only modifiable risk factor. Symptoms such as halos around light, pain, headaches, nausea, vomiting and decreased visual acuity warrants urgent referral to the ophthalmologist or emergency room.

The signs and symptoms start very slowly and the only way to diagnose the condition is to get a detailed medical exam that measures changes in the visual field. The earlier treatment is sought, the better in order to preserve and prolong the integrity of the major eye nerves.

Latino/Hispanic Individuals above the age of 60, African Americans above the age of 40 and people that have a family history of glaucoma are at a higher risk and regular eye exam is recommended for these categories of people. Other conditions that may cause or worsen glaucoma include:

• Use of corticosteroids: These are commonly known as steroids. They are commonly available as tablets, injections, inhalers, lotions, gels or creams. They are used to reduce inflammation and suppress the body’s protective instinct called the immune system.

• Drugs with antimuscarinic activity: This class of drugs prevents transmission of certain signals in the brain. They include drugs like diphenhydramine (Benadryl) and benztropine (Cogentin)

• Anticonvulsants: These are medications used to prevent seizures. Examples include Topiramate (Topamax)

• Use of oral contraceptives: These are medications used to prevent pregnancy. Long term use of more than three years has been associated with glaucoma.

GLAUCOMA TREATMENT

Controlling pressure in the eye is usually the first step in people with elevated values. Patients with open angle glaucoma with normal eye pressures will benefit from further lowering their eye pressure. This can be achieved using medications and or surgery. In order to get maximum efficacy and optimal reduction of intraocular pressure, a number of these medications can be combined. Signs and symptoms of dry eyes should also be identified early in the management of glaucoma.

Prostaglandin and Prostamide Analogues

These include latanoprost (Xalatan), travoprost (Travatan Z), latanoprostene bunod (Vyzulta) and bimatoprost (Lumigan). These medications are very effective and are the go-to medications in glaucoma treatment. They help to preserve vision and delay progression of vision loss. They are very safe with good safety profiles.

Beta Blockers

These include betaxolol (Betoptic) and timolol (Timoptic). These medications protect the visual field. They are however contraindicated in people with certain heart and airway conditions.

Alpha2-adrenergic Agonist

The main drug used in this class is brimonidine (Alphagan). This class of medications have adverse ocular effects which mostly limits their use.

Carbonic Anhydrase Inhibitors

These include dorzolamide (Trusopt) and brinzolamide (Azopt), which are commonly used as additional therapy or as the primary therapy in patients with heart contraindications to beta blockers.

Cholinergic Agonists

Pilocarpine (Isopto Carpine) contracts the eye muscles to increase tear flow. Its use is limited by side effects such as reduced night vision and brow ache.

In conclusion, dry eyes and glaucoma are both chronic conditions often occurring concurrently in the older populations. Some glaucoma eye drops can make dry eye condition worsen, carefully choosing the right glaucoma medication can help in reducing the risk of dry eye occurrence and progression. Also avoiding benzalkonium chloride by using alternatives and preservative -free single dose units will go a long way in reducing the incidence of dry eyes in glaucoma patients. For people above 40 years of age and even younger if any sign or symptoms of dry eyes and or glaucoma is experienced, regular eye check is recommended. Talk to your eye doctor if experiencing any unusual symptoms.

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