Dry-eye Syndrome
Chat Highlights
September 5, 2007

On Wednesday, September 5, 2007, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Dry-eye Syndrome".

Moderator:  Welcome back to chat, Dr. Wilson.   Will you please start the discussion of dry-eye syndrome?

Dr. Rick Wilson:  Okay.  Many tiny glands lining the eyelids produce the three components of tears: a watery solution, mucous, and oil.  The watery solution keeps the external eye moist and the cornea clear; the mucus keeps the watery solution in touch with the cornea; the oil slows the evaporation of tears.

Normally, a dry eye occurs when either the watery or oily part of the tears is insufficient.  Many patients with dry eyes complain about globs and clear strands of mucus, which they can pull out of the eye.  Those globs and strands occur because the dry eye still makes mucous, but there is not enough of the watery component to keep the mucous in solution.

Moderator:  How is dry eye diagnosed?

Dr. Rick Wilson:  Often, a dry eye can be diagnosed just from the symptoms of a tired, scratchy, or sandy feeling in the eyes.  Those symptoms usually occur in the evening, rather than in the morning.  The symptoms are aggravated by a poor night's sleep, smoking or smoke in the air, dry air (say from dry heat in the winter), working too long at paperwork, or staring at a computer screen without blinking enough to keep the corneas wet, etc.

When I was a resident I had to stop wearing contact lenses because they made my dry eyes worse.  The main symptom I had was that my eyes would want to close whenever I wanted to read and I would often fall asleep.

P:  All morning and evening, my eyes feel painful and numb, and as if they have sand in them. Is that caused by dry eyes or by the two trabeculectomies I had?

Dr. Rick Wilson:  Could be both, depending upon the shape of your bleb.  If you had a corneal abrasion or erosion in the peri-surgical period, pain upon opening your eyelids in the morning can be the result of a persistent pulling off of a small portion of the cornea covering.

Moderator:  What does an eye doctor look for when examining a patient for dry-eye syndrome?

Dr. Rick Wilson:  The examination will include inspecting the tear film covering the cornea with the slit-lamp microscope.  A tear film that remains evenly spread over the cornea only a few seconds is abnormal. Instilling an orange or red dye in the eye will reveal dry spots on
the cornea, where the cornea is not being kept wet.  A thin strip of filter paper can be placed with one end just under the lower eye lid and the amount of tear production measured over five minutes. Some cornea specialists obtain a small sample of the tears for analysis.

P:  What effect do dry spots on the cornea have?

Dr. Rick Wilson:  Dry spots slightly decrease visual acuity.  It’s like looking through mildly pitted glass, rather than the smooth surface that a nice coating of tears is supposed to provide.  The dry spots are also uncomfortable, and almost any type of eye drop stings a lot.  That’s because the usually slightly acidic drops hit the irritated cornea directly, rather than being diluted by the tear film.

P:  Can the stages of dry eyes be differentiated?

Dr. Rick Wilson:  The differentiation is somewhat subjective, and depends upon the extent of the patient's symptoms and the extent of the physical signs on examination.

P:  Do any of the glaucoma drops contribute to dry-eye syndrome?

Dr. Rick Wilson:  Yes. In some people, the beta blockers cause a slight anesthesia that inhibits blinking and exacerbates dry eyes.  Cold medications, antihistamines, diuretics, and birth control pills can also increase dry-eye symptoms.

P:  What treatments are available for dry eyes?

Dr. Rick Wilson:  The most common treatment for dry eyes is drops or “artificial tears” that temporarily relieve symptoms by restoring fluid to the eye.  The drops, however, relieve symptoms only for the short term, and don't solve the underlying problem.  A new generation of artificial tear products has an "anti-evaporative" effect that prolongs the effectiveness of the products. Soothe (Alimera Sciences), Refresh Endura (Allergan), and Systane (Alcon) are examples.

I have had great success with the addition of one tablespoon of flax seed oil or two tablespoons of ground flax seed per day to the diet.  The addition of the right balance of omega-3’s, 6’s, and 9’s often make the dry-eye symptoms go away.  I swear by it for myself and my patients.

The next step after frequent instillation of artificial tears and omega-3 supplementation is an anti-inflammatory drop called Restasis.  Restasis is expensive and burns slightly on being applied, but it can reverse some of the changes seen with dry eyes.  Unfortunately, little effect from Restasis is seen before four to six weeks.  The full effect requires three months of use.

Finally, the doctor can insert small plugs into the tear ducts (punctal plugs) so the tears won't be drained off.

P:  Do lubricating eye drops affect the intraocular eye pressure?

Dr. Rick Wilson:  No.  The fluid in the eye (aqueous humor) is entirely different from the fluid on the outside of the eye.

P:  Is extreme dry eye, especially at night, caused by glaucoma eye drops?  I use Cosopt, Alphagan P, and Xalatan.

Dr. Rick Wilson:  Dry eyes are made more symptomatic by the preservatives in the glaucoma drops, as well as by the medications themselves.  Remember, the drops are usually slightly acidic to prolong their shelf life.  This acidity causes a burning sensation in a dry eye, whereas it might not cause that effect in a normal eye at all.

P:  Two months after having had trabeculectomies in both eyes, I had a sensation in both eyes of pain, heaviness, and numbness all day, every day.  Are those symptoms of dry eyes?  I’m now using Restasis and Cellufresh, as well as Tobradex and Vidisic.  How long is Restasis effective for dry eyes?

Dr. Rick Wilson:  I've been using Restasis for three to four years, and it is still effective. If you don't have an infection, I would certainly stop the tobramycin part of the Tobradex.  That antibiotic, like all antibiotics, is brutal to bacteria, but not too gentle to the eye.  Two months of constant use may create a problem.  Then, too, after a trabeculectomy, the conjunctiva is raised off the sclera and extends out further from the eye, exposing it to increased drying.

P:  I have read that the preservative, BAK (benzalkonium chloride) is bad for the cornea and has been removed from most OTC (over the counter) lubricating eye drops.  However, many glaucoma drops, such as Lumigan, still contain BAK.  Why is BAK still being used when there are less harmful preservatives available?

Dr. Rick Wilson:  Changing to a different preservative in medications that have already been approved by the FDA (Food and Drug Administration) requires a reformulation review.  That is expensive.  Most companies produce new drugs with the new preservative, but leave their proven drugs unchanged.

P:  When I first started using glaucoma eye drops, I needed very little pressure reduction.  I elected to try Rescula as my first medication.  Rescula was in an artificial-tears base, and it actually soothed my eye, making it much more comfortable than the untreated eye.  Do any of the currently available medications contain such a base?  Do any of them not contain BAK as a preservative?

Dr. Rick Wilson:  All of the glaucoma drops come in an artificial tear vehicle. I agree that Rescula was very mild and easily tolerated. I hated to see it removed from the market because it was not as effective as Xalatan.  The percentage of BAK differs among the different drops.  Alphagan P has a different preservative (Purite), but has a higher allergy rate, so the benefit cancels out.

P:  My question concerns dry eyes and eye socket pain, felt deep inside the eye.  I have a possible diagnosis of pigmentary glaucoma. Is pain in the eye socket associated with either dry eyes or pigmentary glaucoma?

Dr. Rick Wilson:  Deep eye socket pain does not sound like dry eyes.  If the pain is an ache accompanied by glary vision or colored rings around lights and occurs after exercise or a movie, it could be related to pigmentary glaucoma.

P:  Would dry eyes make vision blurry, especially in one eye upon first awakening from sleep? The blurry vision clears in 20 minutes.

Dr. Rick Wilson:  The movement of the eye lid across the cornea keeps the cornea wet.  If the eye lid isn't moving (as in sleep) and there is very little moisture, the cornea could be affected for a while after arising.  Usually, though, the eye lid acts to retain the moisture and keeps the eye more moist than usual.  Therefore, symptoms become worse as the day progresses.  The increasing evaporation saps the eye's ability to make tears.

P:  I have had very dry eyes since I was diagnosed with glaucoma a year ago.  I believe my dry-eye problem was caused by laser surgery.  Restasis has not helped.

Dr. Rick Wilson:  If you are not on a blood thinner, it certainly wouldn't hurt to try the flax seed regimen I mentioned above, or concentrated fish oil capsules to give your lids the omega 3, 6, 9 they need to make tears.  LASIK surgery causes dry eyes for several months, but other types of laser surgery typically do not cause dry eyes for more than a week.

Moderator:  Thank you, Dr Rick.

Dr. Rick Wilson:  Good night, everyone.  Have a good two weeks.

On September 19 Dr. Pro discussed "Life After Shunt Surgery" in the Chat room. Click here for highlights of that meeting.

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