What separates a neuro-ophthalmologist from an ophthalmologist? The answer is: “About an hour”-that is, the time difference spent with the patient. This witticism also reflects the situation when we examine and treat patients with symptomatic ocular surface dryness (or glaucoma). These patients merit a thorough workup, ample patient education, and prescheduled follow up.
Four main categories bear discussion here:
• The diagnostic workup
• Topical therapy (artificial tears, loteprednol, cyclosporin)
• Physical therapy (plugs, shields, humidifiers)
• Oral therapy (fatty acids, doxycycline)
The Diagnostic Workup
History alone is highly sensitive and specific for dry eye syndrome (DES). The only confounding factor is the symptomatic overlay of ocular allergy. Dry eye syndrome and allergic conjunctivitis are highly prevalent disorders, so it is no surprise that there is large overlapping of these populations.
The relatively easy separation of the “itchy-burny” eye goes like this: If the predominant symptom is burning, consider this as primary dry eye with secondary opportunistic allergy expression. In other words, if this patient had a normally functioning tear film, there would be no itching. On the other hand, there are plenty of patients who truly have concurrent allergic eye disease and dry eyes.
When you hear complaints of a dry, tired, gritty, sandy, burning feeling, particularly as the day wears on, the diagnosis is obvious. There are doctors who would then pursue a subdiagnosis regarding a mucin, aqueous, or oily component dysfunction-for there are three somewhat separate tissues involved in the synthesis and maintenance of all three tear components. In keeping with our pursuit of clinical simplicity, however, we recognize that aqueous deficit and/or oily layer dysfunction are by far the two most common subtypes of dry eye syndrome.
Beyond the history, additional observations can be helpful in quantifying the degree of severity:
• Lacrimal lake. Slit lamp evaluation of the height (volume) of the lacrimal lake.
• Tear film breakup time (BUT). This is a nonspecific indicator of the stability of the tear film. A BUT of a few seconds can reveal severe DES; 8 to 12 seconds, moderate; and 12 to 15 seconds, mild. It should be noted that these are not absolute time gradients, rather a general guideline.
• Lissamine green vital dye staining. Because of the stinging associated with rose bengal dye, it has been replaced in most doctors’ offices by lissamine green. Both dyes demonstrate identical staining patterns and can reveal and quantify any evidence of corneal and/or conjunctival epithelial tissue compromise. Such testing is rarely indicated (except in working up a patient for suspected superior limbic keratoconjunctivitis), but can be useful in gauging the tissue response to therapy. We usually use subjective symptomatic relief as our marker of therapeutic progress.
Although there are a variety of other diagnostic devices and instruments available, we find the above evaluation to be highly sensitive and specific.
Preservative-free, transiently-preserved, or non-toxically preserved artificial tears remain the mainstays of topical therapy.
Unless there is obvious meibomian gland dysfunction, initiate a trial of premium quality artificial tear therapy. Encourage the patient to adhere as closely as possible to using the artificial tear every two to three hours to determine if such therapy can alleviate symptoms. We generally have our patients return for a follow-up evaluation in two to four weeks.
Our favorite artificial tears are the Moisture Eyes line of lubricant drops, GenTeal, Tears Naturale Forte, and TheraTears, although there are plenty of other excellent products available. It will be interesting to see how Systane and Refresh Endura perform. Patient compliance with glaucoma medications is a breeze compared to the abysmal performance of dry eye patients. Neither of us have more than a handful of patients who use artificial tears as consistently as we recommend. Any maneuver that can diminish the need for frequent instillation of the artificial tears is always welcomed, thus explaining the popularity of tear preservation systems such as punctal occlusion. This is very popular with busy patients and those patients whose jobs make compliance with frequent instillation difficult.
One underutilized topical therapy is the corticosteroids. It is well-recognized that inflammation can play a significant role in lacrimal gland function. Bottom line: In those patients with marked pain, photophobia, and misery as a result of surface desiccation who are minimally or very transiently helped by artificial tears, try a pulse dose of Lotemax (loteprednol etabonate 0.5%, Bausch & Lomb) q1d for one week, then bid for two weeks concurrently with frequent use of a preservative-free artificial tear. This consistently brings relief to this subset of dry eye patients. Such therapy can be safely re-pulsed every three to six months as needed. Some doctors suggest using a drop of potent steroid qd or qod as maintenance, and this approach is rational.
The newly released cyclosporin ophthalmic emulsion (Restasis, Allergan) is another therapeutic approach that may help curb the inflammatory component of some patients with moderate to advanced dry eyes. Restasis is dosed bid chronically, and is dispensed in unit-dose containers (see “Update on Cyclosporin,” page 49A).
Using devices to help preserve physiological tears is a concept that continues to enjoy great popularity. While room or home humidifiers and side-shield protective eyewear can be helpful, punctum plugs capture the greatest attention. There are numerous manufacturers of these wonderful little devices, and no objective, head-to-head comparison of them has been done. We have no idea which of these is “the best,” and everyone has their favorites. (Our favorite is the Tear Savers brand.)
Punctum plug therapy alone is not well-suited, however, for patients with little or no lacrimal lake. You have to have something to save in order to save it. (You can quote us on this.) Even if the lake volume is very low, punctum plugs can help prolong ocular surface residence time of artificial tears. Fortunately, the majority of dry eye patients have low to moderate lacrimal lakes, and occlusive therapy can be quite beneficial.
What about doing a trial of collagen (dissolvable) plugs first? We see little need for such. If patients are helped with artificial tears, yet are unable or unwilling to use them as frequently as needed to maintain an acceptable level of comfort, a “permanent” plug will almost invariably be beneficial.
We most often plug the inferior punctum of the more symptomatic eye first, and re-evaluate the patient in one month. If successful, we usually plug the other lower punctum. Be sure to explain to these patients that they will likely need to continue artificial tear therapy, though less frequently than pre-occlusion.
There is a wide variety of plug designs, however only two main types exist: intracanalicular and punctal. While there are advantages and disadvantages to both approaches, we strongly prefer the punctal design.
The advantage of the intracanalicular/sub-punctal design is that it should be comfortable, since none of the device can extrude to irritate the ocular surface. The major disadvantage is that it is nearly impossible to know if the plug is indeed anatomically residing within the target tissue. Obviously, if the patient is rendered asymptomatic, one would logically assume it is properly placed.
Conversely, if the patient remains symptomatic, it is extremely difficult to know if the device is in the canaliculus, and therefore leaves the clinician in a quandary as to whether to re-plug the same canaliculus, or plug the ipsilateral superior canaliculus.
However, another disadvantage is the uncommon patient who develops epiphora, or a chronic or acute canaliculitis or dacryocystitis. Here, the plug needs to be removed. This can be simple if the device can be irrigated into the lacrimal sac, or even pushed there with a Bowman probe; however, there are times when surgical excision is required; this applies to both the Lacrimedics plug as well as the newly approved SmartPlug technology (Medennium).
The advantage of the more commonly used punctal plugs is that they can be readily observed, and easily removed if ineffective. The major disadvantage is that they can become partially or totally extruded. Plug loss is -a common occurrence, but one that can be greatly minimized by measuring the punctal opening with a punctal gauge, and going one-half to one size larger via good punctal dilation.
There are times when it is necessary to occlude all four puncta. When the superior puncta are occluded, epiphora occasionally results. For this reason, when we do need to do more than inferior punctal occlusion, we generally try a “flow controller” plug to achieve partial occlusion. Granted, this is a fine-tuned approach, but one that has performed well in our hands.
If whatever plug design and approach has been successful, and yet plug loss occurs, one can either try a larger plug size or default to thermocautery of the vertical canaliculus, whichever is deemed to serve the patient greater good.
Meibomian gland dysfunction commonly results in the subnormal function of the oily layer, resulting in evaporative dry eye. This can occur in isolation, but usually coexists with abnormal lacrimal gland (aqueous layer) insufficiency.
There are two systemic approaches to enhance meibomian gland function: doxycycline and nutritional supplementation. When clinically indicated, we prescribe two 100mg capsules of doxycycline qd for a month, then 100mg qd for six months, and then 50mg for six more months or longer.* A “must read” article is “Meibomian Gland Dysfunction,” by Drs. Driver and Lemp, which appeared in Survey of Ophthalmology, MarchApril 1996.
Toward the end of this masterful article, the authors stress that doxycycline therapy must be used for (`several months” to reach its full therapeutic potential. For perspective, keep in mind that dermatologists keep patients on tetracycline for years and years with good success. We generally stop doxycycline therapy somewhere around one year, and see how long the patient can remain comfortable. If the patient becomes symptomatic again, and the doxycycline was well-tolerated, we usually restart it at 100mg or 50mg qd, based upon clinical judgment.
Beyond, or perhaps instead of, doxycycline, you can try nutritional supplementation. There seems to be consistent thought that omega-3 fatty acid supplementation can be beneficial in patients with dry eyes, particularly so if there is evident meibomian gland dysfunction.
Fatty acid metabolism is complex. Here’s the succinct version: There are good (anti-inflammatory) and bad (pro-inflammatory) end products of fatty acid metabolism. Omega-3 essential fatty acids,
found abundantly in fish oils and flaxseed oil, are metabolized into prostaglandin and leukotriene subtypes, which render an anti-inflammatory, therapeutic effect.
Flaxseed oil is generally recommended at a dosage of 2,000mg per day. The two main products we recommend for this are TheraTears Nutrition (Advanced Vision Research) in gel capsule form, and Hydrate Essential (Cynacon/Ocusoft) in liquid form. Flaxseed oil is also available in health food stores.
No definitive approach for oral therapy is established. It might be best to try omega-3 supplementation first, but do not hesitate to try doxycycline if omega-3 supplementation fails to give relief after two to three months.
In summary, we now have available to us a plethora of approaches to help patients with dry eyes. Surely now, a compassionate, knowledgeable doctor can bring relief to most patients with symptomatic dry eye. It is difficult to set a therapeutic flow, but it probably is wise to:
• Discourage use of vasoconstrictors.
• Guide dry eye patients toward top-quality artificial tears-and how to use them properly.
• Consider punctal occlusion.
• Consider addition of loteprednol (pulse-dosing) or cyclosporin (chronically) to artificial tear therapy.
• Consider oral omega-3 or doxycycline therapy.
There is no consensus of expert opinion regarding how, or when, or in what order to apply these interventions. In most cases, two or more therapies may ultimately be used concurrently.
It is important to proceed stepwise and methodically so that each approach is given timely therapeutic evaluation. Try to avoid instituting two interventions simultaneously, since it would then be difficult to know which intervention worked better, or at all.
Finally, many doctors regard dry eye as a second-class, boring eye disease. In reality it is the single most treatable eye disease, and a very common patient presentation that adversely affects the quality of our patients’ lives. We invite you to step up to the challenge and approach these patients with renewed excitement and determination.