Index
Ocular Surface Anatomy
Dry Eye Symptoms
Diagnosis of Dry Eye
Common Causes of Dry Eye
Treatment of Dry Eye

“Dry eye syndrome” is a catch-all term often used by eye doctors to describe a group of ocular surface disorders that cause a similar list of symptoms. As the name implies, the primary symptom of these conditions is a dry, irritated, scratchy sensation in the eyes. Other symptoms, detailed below, will vary with the specific disorder causing the problem, and therefore a correct diagnosis is important in order to arrive at the proper treatment plan.

The term ‘dry eye syndrome’ also might lead some to think of these conditions as insignificant and unworthy of serious attention. And while many cases of dry eye are relatively benign and straightforward to manage, many others cause symptoms that are severe and defy simple treatments. Patients may suffer from moderate to severe pain, blurred to extremely poor vision, and even ulceration and scarring of the cornea leading to permanent vision loss. Again, proper diagnosis is critical so that treatment can be tailored to the specific issues, avoiding long-term suffering and complications.

The Ocular Surface Disease Index (OSDI) is a scale which was developed by a number of ocular surface disease experts as a means of helping patients and physicians evaluate the severity of dry eye syndrome and the impact of its symptoms on the patient's lifestyle. By completing the index and bringing it with you to your next appointment, you will help your eye doctor better evaluate and treat your condition. The OSDI can be downloaded by clicking here.

The remainder of this article will describe the different conditions leading to dry eye, the associated symptoms, methods of diagnosis, and treatment options.

Ocular Surface Anatomy

The ocular surface consists of the cornea and conjunctiva, both of which are mucous membranes, similar to the inside of the mouth. In order to remain healthy and function properly, these tissues must remain moist at all times. Lack of moisture on the eye’s surface, caused by a number of different conditions, causes a breakdown of the cells that line the surface of these tissues, leading to pain and the other symptoms detailed below.

The moisture found on the ocular surface is produced by the cells of the lacrimal (tear) glands. These cells are located both throughout the conjunctiva as well as in a large, main lacrimal gland above the eye. While the main lacrimal gland is primarily responsible for producing tears when we cry, the accessory glands in the conjunctiva produce the basal level of liquid needed to keep the eyes moist. This liquid is the main ingredient in the tear film, the thin layer of moisture that covers the eye (or at least that should) at all times. The tear film is actually made up of three distinct layers, each of which is important for the proper function of the film:

• Aqueous layer: this is the liquid described above, the watery fluid produced by the lacrimal glands. This layer makes up the majority of the tear film. In addition to protecting the eye by keeping it moist, the aqueous layer contains a number of substances that further help maintain eye health by nourishing the surface epithelial cells and killing bacteria and other harmful organisms.
• Mucin layer: mucin is a thick, sticky substance produced by the goblet cells of the conjunctiva. Mucin essentially fills in the nooks and crannies on the ocular surface and reduces surface tension, allowing the aqueous layer to flow smoothly across the entire eye. A deficiency of the mucin layer leads to dry patches on the ocular surface, similar to the dry areas on a freshly waxed car. Without mucin as its foundation, the aquous layer will not form properly.
• Lipid layer: lipids, or oils, are produced by the Meibomian glands on the margins of the eyelids. These oils float on the surface of the aqueous layer (remember, oil floats on water), stabilizing it and preventing excessive evaporation. A deficiency of the lipid layer will lead to rapid evaporation and loss of the aqueous layer. If aqueous layer production cannot keep up with loss, symptoms of dry eye develop.

All three of the tear film layers must be present in proper amounts in order to form a stable, healthy film. A problem with any layer can lead to similar symptoms. Treating the correct problem goes a long way toward relieving those symptoms.

Back to Content List

Dry Eye Symptoms

• Pain, feeling of dryness, burning, or scratchiness
• Gritty, foreign-body sensation: The cornea is very sensitive to injury. Even the tiny dry spots caused by dry eye can feel like large grains of sand stuck in the eye.
• Light sensitivity
• Excessive tearing: This may seem counterintuitive. However, as the ocular surface is injured by lack of adequate moisture, reflexive signals are sent to the main tear gland stimulating the production of tears in an attempt to better moisten the eye. In this way, dry eye sufferers often cycle between feeling overly dry and overly wet.
• Redness
• Blurred vision: The cornea is the primary refracting (focusing) surface of the eye. If it isn’t kept smooth and regular by a proper tear film, vision is blurred. Additionally, excessive tearing can also affect vision.
• Eyes feel “tired” or heavy
• Eyes tire quickly after reading for short period
• Itching
• Sticky feeling with excess mucous production
• Crusting of eyes in the morning
• Eyelids stuck together in the morning

Back to Content List

Diagnosis of Dry Eye

The history and symptoms reported by the patient are frequently enough to make an eye doctor very suspicious that dry eye is an issue. The ocular examination can then be tailored to look for the signs of ocular surface disorders.

• The eyelids- specifically the Meibomian oil glands, are examined for the presence of inflamed, clogged ducts. Often thick, greasy secretions can be seen blocking the openings of these ducts. Abnormal oils can also be seen in the tear film itself, much like the rainbow patterns of oil seen in puddles after a rain.
• The tear film is evaluated to determine its regularity and consistency. A deficiency in the quantity of the tear film is often indicated by a reduced ‘tear lake,’ the layer of moisture visible at the bottom of the eye between the cornea and the lower eyelid.
• Tear break-up time, the time it takes for the first dry spots to form after a blink, can be measured. This should normally be at least 7-10 seconds.
• Staining of the ocular surface with vital dyes such as fluorescein, Rose Bengal, or Lissamine green is often performed. These substances will stain areas of the cornea or conjunctiva where mucin is missing or where epithelial surface cells are dead or dying, helping to quantify the degree of surface dryness and damage.
• Schirmer’s testing may be performed. In this test, the eye is anesthetized and a small strip of filter paper is placed against the bottom of the eye, in contact with the tear lake. Normally, this strip should blot up at least 10 millimeters of moisture over five minutes. Failure to do so often indicates aqueous deficiency.

The specific findings at examination can help the eye doctor determine the cause and degree of dry eye, helping to establish a treatment plan.

Back to Content List

Common Causes of Dry Eye

• Age
  Lipid production, and possibly aqueous production, decreases with age, causing evaporative dry eye. This is more common in peri- and postmenopausal women, in whom hormonal changes are responsible for more significant changes.
• Contact lens wear
  While not necessarily a direct cause, contact lens wear can exacerbate dry eye symptoms. Soft lenses absorb the tear film. All lenses can irritate the ocular surface by rubbing against the eye. Poorly fitting lenses can cause corneal hypoxia, or oxygen starvation, leading to further cell damage and surface breakdown.
• Disorders of ocular surface and eyelid anatomy
  A number of disorders of the ocular surface and eyelids can cause or exacerbate dry eye.
  
  • Pterygia/pingueculae
  • Epithelial basement membrane dystrophy (map-dot-fingerprint dystrophy)
  • Subepithelial fibrosis
  • Corneal scars
  • Proptosis (bulging eyes), most commonly associated with thyroid eye (Graves) disease
  • Lagophthalmos, or failure of the eyes to fully close, caused by Graves disease, blepharoplasty, Bell’s palsy, etc. This may occur only at night and go unrecognized.
• Disorders of the Meibomian oil glands
  Blepharitis/Meibomian gland dysfunction- primary responsible for lipid layer deficiency, causing evaporative dry eye. These conditions are detailed here.
  
• Environmental factors
  Hot, dry, dusty climates tend to exacerbate dry eye, while symptoms are often relieved in humid, cooler areas. Many of our snow-bird patients comment that their dry eye symptoms are significantly reduced while back in the Pacific Northwest or the Midwest, however recur immediately upon returning to southern Arizona. Use of central heating or air conditioning, as well as ceiling fans, often exacerbates symptoms.
• Eye surgeries
  Patients who have undergone refractive surgery such as RK, PRK, or particularly LASIK often suffer from dry eye. Corneal transplantation often causes dry eye as well.
  
• Low blink rate
  Blinking is critical for the proper spread of the tear film over the entire eye. Failure to blink regularly and fully can cause dry eye symptoms. Blink rate naturally decreases during tasks requiring sustained near vision, such as reading, working at a computer, or watching television. For this reason, symptoms of dry eye are often reported to occur during these activities.
  
• Medications
  Many medications can cause or exacerbate dry eye. Side effects of medications can be found on the product insert that came with the medication, or online at a site such as Drugs.com. If you believe your medications may be responsible for your dry eye symptoms, discuss alternative treatment with your physician. And remember, never stop a medication on your own without first consulting your physician.
  
  • Antihistamines and decongestants
  • Some antidepressants
  • Certain types of blood pressure medications, such as central-acting agents and diuretics
  • Birth control pills
  • Beta blockers
  • Pain relievers, such as ibuprofen (Advil, Motrin) and naproxen (Aleve)

Back to Content List

Treatment of Dry Eye

As this article has indicated, there are numerous potential causes of dry eye syndrome. While treatments offered are often similar regardless of cause, certain factors must be addressed specifically to achieve the best resolution of symptoms.

• Artificial tears
  For better or worse, these products remain the mainstay of dry eye treatment today. These are simply formulations of various wetting/moisturizing agents that are applied topically (as eye drops) multiple times daily, however often necessary to alleviate symptoms. Artificial tears are simply palliative- they temporarily reduce symptoms without affecting the underlying condition. Not all tear products are equal, and different patients tend to prefer one over the others. It is recommended that a number of these products are sampled in order to find that which works best for you.
  
  For patients with poor nighttime lid closure (lagophthalmos) or other issues causing dry eye at night or in the early morning, moisturizing gels and ointments can also be used as necessary.
  
  
• Punctal plugs
  As moisture is constantly being produced on the ocular surface (or at least should be), it must also have means to drain away. This is accomplished via the nasolacrimal duct, a tiny tube that passes from the inner corner of the eye and drains into the back of the nose. The entrances to this duct are two tiny opening in the eyelids, one above and one below. These openings, known as puncta, can be plugged up with tiny “stoppers,” essentially blocking the drain. Plugs may be temporary, made of collagen which dissolves after about a week and used as a “trial run,” or more permanent, made of rubber.
  
  Plugs are placed as a minor procedure in the doctor’s office. The eye is numbed with topical anesthetic (eye drops). A small instrument known as a dilator may be used to slightly enlarge the punctal opening in order to allow easier access for the plug. This may be somewhat uncomfortable, but is seldom truly painful. The plug is then pushed into the punctum. Again, there may be some mild discomfort and pressure, but rarely significant pain. The goal is to insert as large a plug as will fit, in order to prevent the plugs from falling out if sized too small. The lower punctum is usually plugged initially, as most tear outflow is via the lower duct due to gravity. The upper punctum can also be plugged if necessary.
  
  Once plugs are placed, there may be mild discomfort or a scratchy feeling for a few days. Beyond that, however, you shouldn’t even know that they’re present, with the exception that you should feel better. Artificial tears can still be used, but hopefully will not be needed as frequently. Medications such as Restatis can also be continued, if desired.
  
  Problems with plugs are rare. Occasionally excessive tearing, known as epiphora, will develop due to the blockage of the puncta. In this case, the plugs can simply be removed and other treatments considered. Rarely and infection or inflammation will develop around or behind the plug, also necessitating its removal and possible short treatment with antibiotic or anti-inflammatory eye drops.
  
  
• Prescription medications
  Currently, the only prescription medication approved by the FDA specifically for the treatment of chronic dry eye is Restasis (cyclosporine 0.05%), manufactured by Allergan and available since 2003. Most eye doctors now have plenty of experience with this product and surely have their own opinions regarding its efficacy. In our practice we have generally had good results with Restasis when used in appropriate patients. It seems most effective in true cases of aqueous deficiency, as its primary means of action is via promotion of aqueous tear production from the accessory tear glands of the conjunctiva.
  
  Restasis is provided in eye drop form and instilled in each eye twice daily. It is generally well tolerated with few side effects. The most common complaint associated with the drug is burning upon use, which can be managed with additional use of topical steroids or additional artificial tear drops. Your physician will discuss these options with you should Restasis be considered.
  
  Topical steroids can also be used to treat symptoms of dry eye, however this class of drugs is preferred for more acute exacerbations. Prolonged use of steroids is preferably avoided, as these medications can cause a host of side effects, including premature development of cataracts and, in some individuals, elevated intraocular pressure and glaucoma. In the short term, however, topical steroids are quite safe and effective at alleviating many symptoms of dry eye.
  
  
• Treatment of Meibomian gland disease
  In cases of significant posterior blepharitis and Meibomian gland dysfunction, treatment must be directed at decreasing the inflammation and improving the quality of the natural oils. This can be accomplished in various ways:
  • Hot compresses: a hot, moist washcloth or other warm pack can be placed over the closed eyes for several minutes. This serves to heat and soften the thick oils plugging the Meibomian ducts, allowing them to flow more freely.
  • Lid scrubs: either the washcloth used as a hot compress or a specifically designed, commercial lid scrub product can be used to gently cleanse the lid margins after the Meibomian secretions have been softened by heat. This additionally helps remove dead, flaking skin as well as excess bacteria.
  • Antibiotics: the oral antibiotics doxycycline and minocycline have long been used to treat Meibomian gland disease as well as its counterpart in the skin known as rosacea. These antibiotics improve the quality of the oils produced by the glands, returning them to a more normal, thin, liquid form and allowing them to flow more freely. Systemic side effects can limit their use, particularly gastrointestinal upset and diarrhea. More recently, a topical antibiotic (eye drop) called Azasite (azithromycin) has been introduced for this same purpose, and may be preferred for some due to its lack of systemic side effects.
  • Omega-3 fatty acid supplementation: Significant anecdotal evidence, as well as increasing evidence from proper research studies, suggests that omega-3 fatty acids may help improve the quality of the Meibomian secretions and stabilize the tear film. Supplementation with either fish oil or flaxseed oil has been recommended as a good source of omega-3s.
• Lifestyle modifications
• Drink plenty of water
• Avoid excessive caffeine
• Avoid excessive air conditioning or use of heat, redirect vents, position away from ceiling fans
• Replace potentially offending medications, when possible
• Autologous serum drops (‘serum tears’)
  For truly severe dry eye that has been poorly responsive to the above, this is an option that, in our experience, can provide good relief. The patient’s own blood is drawn and spun down so that all the blood cells are removed, leaving just the serum, or liquid portion of the blood. This is then separated and placed in vials to be used as eye drops. There are many substances and factors in blood that are very restorative to the ocular surface.
  
  Serum tears must be ordered by a physician and prepared by a hospital or compounding pharmacy that is familiar with the process. Once prepared, up to a six month supply can be stored frozen.
  
  

Back to Content List

The Ocular Surface Disease Index (OSDI) is a scale which was developed by a number of ocular surface disease experts as a means of helping patients and physicians evaluate the severity of dry eye syndrome and the impact of its symptoms on the patient's lifestyle. By completing the index and bringing it with you to your next appointment, you will help your eye doctor better evaluate and treat your condition. The OSDI can be downloaded by clicking here.

Further information

Dry eye syndrome is a much more complicated subject than once believed. An excellent web resource, full of outstanding, detailed, and relatively unbiased information is the Dry Eye Zone. The site can be visited by clicking here.

It matters who you see.