Ocular surface diseases (OSD) are actually a group of diseases that affect — drum roll — the ocular surface. No need to get all mixed up in the jargon though! The ocular surface is just another word for the cornea and the conjunctiva, which is the tissue on the inside of the eyelid and what covers the sclera, or “white” of the eye. Though these disorders affect the top layer of the eye, dealing with an OSD can go deeper than one might expect. The good news is that these diseases are largely treatable with modern medicine, but that doesn’t mean they should be taken lightly. If left undiagnosed, vision loss, blindness, or a significant blow to your quality of life can occur as a result of corneal scarring or other types of damage to the cornea, so it’s best to get checked out if you suspect anything wrong with the surface of your eye.
In general, ocular surface diseases can have many causes, from immunological and systemic issues with the functioning of the body, to the presence of other eye disorders like glaucoma. Refractive surgery like LASIK that changes the corneal surface can also cause abnormalities on the surface of the eye.
Today, we tackle the three most common types of ocular surface conditions: meibomian gland dysfunction (MGD), dry eye disease (DED, also commonly called dry eye syndrome, or DES), and blepharitis. There is a lot of overlap with the symptoms of these diseases, so if you’ve recently been diagnosed or are just curious (or worried) before heading into your next ophthalmologist appointment, let us demystify these scary-sounding syndromes.
Debunking Dry Eye Disease
It’s one of the most common complaints at the ophthalmologist’s office, and with such a high incidence, it’s one that’s bound to rear its ugly head at least once in all of our lifetimes. Dry eye disease (DED), or dry eye syndrome (DES), or keratoconjunctivitis sicca, if you want to be all formal and Latin about it, affects between 20-50% of people around the world, depending on what group the study was performed on. The disease is normally subdivided into two categories: evaporative and aqueous deficient, which are just fancy terms for dryness caused by tear evaporation (evaporative) and for dryness caused by poor tear production (aqueous deficient). Fortunately, you don’t have to be a classical language scholar or a doctor to understand the symptoms, treatment options and underlying causes of DED.
Diagnosis and Symptoms of Dry Eye Disease
Diagnosis of DED can be a tricky topic in ophthalmology because the definition of the disease is just so darn broad. Screening usually starts with a questionnaire to ensure a wide range of symptoms are checked for.
A battery of common tests are used to diagnose DED and other ocular surface diseases. They involve measuring the volume of tears produced by the eye, like the Schirmer’s test, or how quickly the break up of tear film progresses. Checkups on the ocular surface in general may also be made, like fluorescein staining for assessing corneal damage, lissamine green staining for checking out conjunctival or lid margin damage, and looking for conjunctivitis. Of all the methods of diagnosing DED, tear osmolarity seems to reign supreme; a 2011 study found this test to be the most reliable in diagnosis.
The first symptom of dry eye disease is that your eye feels, well, dry. All kinds of symptoms can accompany DED, but most commonly a sensation of stinging, burning, or a feeling that the eye is gritty, or that there is a foreign body lodged in the eye. Vision can also be blurry, affecting visual acuity. Many sufferers also report a feeling of heaviness or tiredness in the eye, and of course the hallmark redness of the eye can also be present.
Risk Factors for Dry Eye Disease
With such a high prevalence and dizzying array of symptoms involved, it shouldn’t come as a surprise that there are so many possible causes and risk factors for developing DED.
Aqueous tear deficient DED can be caused by a wide variety of conditions affecting the eye’s ability to produce tears, like Sjögren’s syndrome, diseases of the lacrimal gland, or drugs affecting tear production.
The common culprit for evaporative DED is the evaporation of the tear film, that thin layer of fluid covering the ocular surface. When this dries up more quickly than your eye can produce it, the eye dries out. Meibomian gland dysfunction is the most common cause of evaporative DED, but other causes include dysfunction with the eye’s ability to open, inadequate blinking, or being in a dry or windy environment.
One of the most important risk factors to note before moving on is bad news for contact lens wearers — wearing contact lenses is a major risk factor, as contacts notoriously dry the eye out and interfere with all kinds of processes crucial to normal tear production and healthy tear film evaporation.
Treatment Options for Dry Eye Disease
There are a wide variety of treatments available to soothe the symptoms of dry eye disease and also treat the underlying cause.
No surprises here, but treatment usually starts with over-the-counter artificial tears. Eye care staples like moisturizing gels and ointments also may help soothe the eye, drastically improving quality of life.
More serious options for the treatment of dry eye include prescription eye drops like cyclosporine (Restasis) and lifitegrast (Xiidra). For dry eye disease related to ocular surface inflammation, topical steroids are often prescribed. A punctal plug may also be used when artificial tears don’t work to block tear drainage and keep more tears on the surface of the eye.
Hot tip: recent research has shown that preservatives commonly used in the treatment of DED and a variety of other ocular conditions may actually be damaging your eyes, so ask your doctor if there are preservative-free solutions.
For some exciting new developments on the cutting edge of treatments for DED, head on over to this page for enlightenment.
Making Sense of Meibomian Gland Dysfunction (MGD)
Meibomian gland dysfunction is so heavily involved in the other two OSD’s that this nasty little bug merits a little bit of discussion on its own. In fact MGD is estimated to be behind a whopping three out of every five cases of dry eye disease, so understanding what’s happening with MGD is essential.
That MGD can be linked to dry eye disease shouldn’t come as a surprise; the meibomian gland secretes a kind of lipid that protects the evaporation of the tear film. The disease can be either symptomatic or asymptomatic, so you may have problems with your Meibomian gland without even knowing it!
Symptoms of Meibomian Gland Dysfunction
As mentioned above, MGD can, in many cases, be asymptomatic. But with symptomatic MGD, the signs indicating MGD overlap greatly with dry eye disease as the function of the Meibomian gland is to keep the eye moist. In fact, there is so much overlap between the two there is a bit of a chicken-or-the-egg debate here — does MGD cause DED, or vice versa? In the end, it’s a moot point, but in addition to the regular DED symptoms, sufferers of MGD may also (but not always) have a telltale uneven inner rim of the eyelid.
Risk factors for Meibomian Gland Dysfunction
Since MGD has so much in common with dry eye disease, it shares a lot of the same risk factors, such as Sjögren’s syndrome and contact lens wearing. Other conditions that can lead to dysfunction are rosacea, allergic conjunctivitis, rheumatoid arthritis, or other autoimmune diseases. Aging also plays a key role, especially because the gland can get blocked by hypertrophy in the epithelium and epithelial cells. Other risk factors include things that affect the eyelid, as damage to the lid can affect the proper functioning of the gland. This includes things like eyelid tattoos and chronic blepharitis; for a more complete list of risk factors for MGD check out this webpage.
Treatment Options for Meibomian Gland Dysfunction
Treatment for serious cases of MGD are best left to an ophthalmologist. Generally speaking, treating the symptoms for MGD are similar to treating DED (see above) because the symptoms of dry eye disease are so similar.
However, there are very simple at-home treatments that are effective for MGD but that might not apply to dry eye. One involves using a hot compress over the eyelids to release the tears and reestablish normal gland function. By soaking a hot compress in boiling water and holding it over the glands, blockages in the may be loosened up and the symptoms may go away in a matter of days. The treatment is so effective that there are even products tailor-made just for this purpose. Another great home remedy is massage of the eyelids, with the same goal of easing blockage. If these don’t work, schedule a follow-up with your eye doctor to explore other options.
Blepharitis
Last but not least is blepharitis. Though it may sound like some kind of horrific disease you might catch on an exotic jungle trek, blepharitis is actually just a fancy word for an inflammatory response in the eyelid. Like the other two diseases we’ve highlighted here today, blepharitis is rarely serious and highly treatable.
Blepharitis comes in two types — anterior and posterior, and are named for where on the eyelid the inflammation occurs. Anterior blepharitis usually occurs where the eyelashes attach, whereas posterior affects where the eyelid attaches to the eyeball. Because of its location near the Meibomian gland, posterior blepharitis is usually related to abnormalities with the Meibomian gland, and MGD (see above).
Signs and Symptoms of Blepharitis
Blepharitis symptoms mimic dry eye symptoms in many ways, with the itchy or gritty sensation in the eye. Added to this, your eyelids might be swollen and red, and there could be (though not always) a telltale crusting of the eyelid, sticky eyelids, or abnormal or abnormalities in the growth of the eyelashes.
Risk Factors for Blepharitis
Anterior blepharitis is usually caused by bacterial infection (called staphylococcal blepharitis) or skin issues like dandruff (seborrheic blepharitis). A less common cause is Demodex mite infestation.
Posterior blepharitis is almost always caused by issues with the Meibomian gland, so MGD is a common culprit here. Scalp dandruff and other dermatological conditions like rosacea are potential causes, so if you are having problems with your skin and are showing symptoms, this is one possible explanation
Treatment Options for Blepharitis
Getting blepharitis under control is largely the same as other OSDs. Taking care of skin issues with your scalp or face and making sure the eyelid is clean by washing regularly is a great way to stop the cycle of buildup on the eyelid. Meibomian gland dysfunction treatments like hot compresses and massage can be great for easing the blockage that can result in posterior blepharitis. Dry eye solutions like artificial tears or other eye drops may help restore normal moisture levels to the eye and relieve symptoms as well.
