While affecting millions of people in the US, dry eye is frequently underdiagnosed. Many dry eye sufferers do not recognize their symptoms are due to the condition of dry eye. Early treatment can decrease progression of severity over time and improve quality of life. Symptoms of dry eye may include burning, itching, excessive tearing, and blurred vision.
WHAT IS DRY EYE?
A deficiency of one or more layers of the tear film causes dry eye. The three main components of the tear film are produced by different parts of the eye.
The conjunctiva is the mucous membrane that covers the sclera (white of the eye) and lines the inside of the eyelids. It contains goblet cells which produce mucin, an important component of the mucous layer of the tear film, and accessory lacrimal glands. The main lacrimal glands of the eye are located in the upper, outer region of the orbit of the eye. These glands produce the aqueous, or watery, layer of the tear film. The eyelids contain oil glands called meibomian glands, which open to the margin of the eyelid. The meibum, or oil, produced by these glands prevents the tear film from evaporating. The cornea is the clear window over the front of the eye, which covers the iris and pupil. The cornea has pain receptors that are hundreds of times greater in density than those of the skin, meaning even minor insult can cause significant pain or discomfort. The medical term for dry eye is keratoconjunctivitis sicca, which refers to the involvement of the cornea and conjunctiva.
ARE MY SYMPTOMS DUE TO DRY EYE?
You may be suffering from dry eye disease if you experience:
Frequent watery eyes
Blurred vision that tends to fluctuate
A feeling of something in your eye
Contact lens intolerance
Increased light sensitivity
Besides the discomfort, dry eye can lead to damage to the surface of the eye, even vision loss, if left untreated.
WHAT ARE THE CAUSES OF DRY EYE?
Dry eye can be part of the normal aging process. It is more common after menopause and affects more women than men. It also increases during pregnancy and in women taking hormone replacement therapy.
Dry eye is associated with autoimmune disorders including systemic lupus erythematosus, rheumatoid arthritis, autoimmune thyroiditis, and Sjogren’s syndrome. Sjogren’s syndrome is a systemic condition that causes dry eyes, dry mouth, joint pain and other symptoms. It can be a primary condition or associated with another connective tissue disorder such as rheumatoid arthritis, lupus, or celiac disease. Inflammation associated with these conditions causes damage to the moisture-producing glands, including the salivary and lacrimal glands.
Medications including antihistamines, nasal decongestants, antidepressants, isotretinoin (Accutane), and certain medications used to treat high blood pressure or Parkinson’s disease can cause dry eyes.
LASIK eye surgery, and other surgeries of the eye or eyelids can result in dry eye. Fortunately, dryness associated with LASIK is not usually severe and typically resolves in 3-6 months. Long-term contact lens wear can cause dry eye by decreasing corneal sensitivity and disrupting the normal tear film dynamics. Contact lens related dry eye can usually be improved or avoided by replacing contact lenses at the recommended interval, changing lens material or case system, or switching to daily replacement lenses. Of course, treating any underlying associated conditions is important.
Other causes of dry eye include allergies, exposure to environmental irritants, air conditioning and heating, and damage to the eye from chemical or thermal burns.
Screen time contributes to dry eye syndrome because a person’s blink rate decreases significantly with concentrated viewing. Blinking lubricates the eye’s surface by pumping oil from the meibomian glands and by spreading the tear film. This decrease in blink rate allows tears to evaporate causing irritation, redness, and blurred vision that typically worsens throughout the day. Preservatives found in artificial tears and glaucoma medications can also contribute to dry eye symptoms.
HOW TO TREAT DRY EYE
There are a number of over-the-counter drops, prescription medications, and home and in-office treatments for dry eye. Typically, lubricant drops known as artificial tears are the first line of treatment. Artificial tears work best when used consistently to prevent dry eye symptoms. Be careful not to use a drop that contains a redness reliever, as these will not treat your dry eye. If you need to use your lubricant drops more than four times per day, a preservative-free drop is recommended. Longer-lasting gels and ointments are also helpful, especially when used at bedtime. If you are not getting adequate symptom relief using lubricants four times per day, you may want to discuss whether other treatment options are best for you with your eye care provider.
Other home treatment options include wearing wrap-around sunglasses when outdoors, using a humidifier, and avoiding vents and fans blowing towards your face.
Some patients with dry eye will benefit from omega-3 fatty acids, either through diet or supplement use. Omega-3 fatty acids are believed to reduce inflammation, an important factor in dry eye. Long-chain omega-3 fatty acids include eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Food sources of EPA and DHA include fatty fish such as salmon, tuna, mackerel and sardines. Short-chain omega-3 fatty acids include alpha-linolenic acid (ALA), which comes from plant sources such as walnuts, flaxseed, chia and some vegetable oils including soybean. ALA may not provide as much benefit as EPA or DHA, because it has to be converted by the body to EPA and DHA.
When conservative approaches in the treatment of dry eye fail, prescription topical medications may be indicated. Corticosteroid eye drops can be used to suppress inflammation to improve dry eye symptoms, especially when symptoms are severe. However, due to potential side effects, steroid drops are not advised for long-term use.
Cyclosporine eye drops (Restasis) are immunosuppressant drops that can increase tear production by reducing inflammation on the surface of the eye. It may take weeks or months before symptom improvement is noticed, and some patients experience burning on instillation of this drop. Cyclosporine drops can be used in addition to artificial tears and other dry eye treatments, and may improve symptoms and decrease the need for frequent artificial tear use.
Lifitegrast (Xiidra) drops are another prescription option for dry eye, obtaining FDA approval in 2016. Lifitegrast works by blocking a mediator of inflammation associated with chronic dry eyes. Possible side effects include blurred vision, unusual or unpleasant taste, eye irritation, and blurred vision. Improvement in dry eye symptoms may occur in 2-6 weeks.
Another prescription option for dry eye is Lacrisert. Lacrisert is a tiny insert made of hydroxypropyl cellulose. It comes with an applicator that allows you to insert it in the space between your eyeball and lower eyelid, and is used once per day. As the insert dissolves, it releases a lubricant throughout the day, and can be used to reduce the need for frequent artificial tears. Possible side effects include temporary blurred vision and irritation.
Punctal plugs are an option for dry eye that does not respond to the use of lubricant drops. These are tiny silicone or collagen inserts that block the drainage of tears through openings in the eyelids, allowing tears to remain on the eye longer. Punctal plugs are generally well-tolerated and reversible. Permanent closure of these openings can be done through a procedure called punctal cautery.
Autologous serum drops are produced using serum from your own blood. They are used when severe dry eye does not respond to any other treatment. It’s thought that growth factors and nutrients present in the serum may provide something that may be missing in patients with severe dry eye. This treatment option requires periodic blood draws and isn’t widely available, yet may be a viable option for some patients.
THE ROLE OF MEIBOMIAN GLAND DYSFUNCTION IN DRY EYE
Many dry eye sufferers have meibomian gland dysfunction, or MGD. The meibomian glands are the oil glands located in the eyelids which produce a substance that prevents evaporation of the tear film. MGD can result from obstruction of the glands, changes in the quality or quantity of oil (meibum) they express, or possibly a combination of both scenarios. This is in contrast to aqueous deficient dry eye, which is often secondary to a systemic condition such as Sjogren’s syndrome. Both conditions can be present in the same patient.
Chronic blockage of these glands can lead to structural changes and permanent loss of function. Screen time and the associated decreased blink rate, contact lens wear, and rosacea may all contribute to MGD. Left untreated, MGD can cause progressively worsening dry eye symptoms.
So while MGD is a chronic condition, many treatment options are available. Regular, often daily, care may be needed to improve symptoms and decrease progression of this common condition. Warm compresses and lid scrubs are frequently recommended to treat dry eye and MGD. Warm compresses improve flow of meibum and soften debris that accumulate near the lashes or contribute to plugging of the glands. Lid scrubs help to stimulate the glands while removing excess oil, bacteria and debris. Commercially available lid scrub products are readily available over-the-counter. Dilute baby shampoo or a mild soap can also be effective. In some cases, topical or oral medications are helpful in the treatment of MGD that does not respond to conservative management. While availability is limited, LipiFlow, an in-office procedure to help clear blocked meibomian glands, may be right for some patients. By gently heating and applying slight pressure to the eyelids, this device is designed to restore oil flow from the glands to the tear film.
THE FUTURE OF DRY EYE THERAPY
Neurostimulation offers a new mechanism for the treatment of dry eye syndrome. By stimulating nerve pathways responsible for producing the three components of the tear film (lipid/oil, aqueous, and mucin), this procedure may benefit dry eye patients in the future.
Every patient experiences dry eye differently. While many patients will never be symptom free, and no cure exists for dry eye, with appropriate treatment quality of life can be greatly improved.