History provides dry eye diagnosis, testing provides etiology

Issue: October 2000

Questionnaire, fluorescein, rose bengal

Eric E. Schmidt, OD: It is extremely difficult to choose just three tests because the dry eye condition takes on many different forms and presents itself differently. It’s important to understand that dry eye is not a “one size fits all” disease. However, there are some tests that I feel are important in every patient for whom you are trying to diagnose dry eye.

First is a patient questionnaire. This should be done before the doctor sees the patient. It is valuable in alerting the doctor to the presence of the disease and aids in determining the severity and type of dry eye.

Instillation of sodium fluorescein (NaFl) dye is also very valuable. This allows you to observe several things in the patient. The presence of NaFl staining indicates epithelial breakdown. If the cornea stains positively this indicates a more severe case of dry eye and alerts you to the need to be more aggressive in your treatment. NaFl dye also is used to conduct a tear break-up time test (TBUT). This provides you with information as to whether the disease is evaporative in nature or due to a decreased tear production. The TBUT is also helpful in assessing improvement in the condition on follow-up visits.

The third test I invariably recommend is rose bengal (RB) stain. RB is a vital dye that stains positively when cell death has occurred or if a tissue is mucin-deficient. This analysis is important in dry eye, as it helps us to determine the severity of the disease. Positive RB stain in dry eye means to me, clinically, that goblet cells have diminished in number and a more severe problem exists. Improvement in RB staining also tells me that the treatment initiated is working for the patient.

Eric E. Schmidt, OD, is the director of the Bladen Eye Center, where he specializes in the treatment of ocular disease. He can be reached at the Bladen Eye Center, 409 E. Broad St., Elizabethtown , NC; (910) 862-4268; fax: (910) 862-2057; e-mail: Kenziekate@aol.com. Dr. Schmidt has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

History, fluorescein, Zone Quick

Albert M. Morier, OD: The most important test to diagnose dry eye is a good case history. Successful treatment of any malady depends first on a good diagnosis. Other pathologies such as blepharitis and meibomianitis mimic aqueous-deficient dry eyes. Dry, scratchy gritty eyes upon awakening, improving during the day is most likely a blepharitis or meibomianitis. Medications, age, sex, systemic conditions, computer or contact lens use can increase the likelihood of dry eye.

If the patient has significant dry eye symptoms, I will then use sodium fluorescein to look for staining patterns. I use a very small amount so as not to add a volume of liquid into the eye. Inferior staining on the cornea may indicate blepharitis or exposure keratopathy. Interpalpebral staining often is associated with aqueous-deficient dry eye. Conjunctival staining may indicate early dry eye, as the conjunctiva stains before the cornea due to the lack of tight junctions between the cells. This allows quicker water loss from the tissues. Corneal staining comes later due to the tight junctions between the corneal cells, which resist the loss of water.

A short TBUT is not specific for aqueous-deficient dry eye because mucin deficiency presents the same way. However, any TBUT less than 8 seconds certainly demonstrates a deficiency in your patient’s tear film. If it is normal, you won’t spend a lot of wasted time and effort in treating the condition.

My final tests are really the same. I use the Zone Quick (Oasis Medical, Glendora, Calif.) phenol red thread test as a measure of aqueous production. The test takes 15 seconds and does not require anesthetic, so I am not “polluting” the test site. If this test does not demonstrate aqueous-deficient dry eye then I will do a Schirmer II. The Schirmer II is performed for 5 minutes and a drop of proparacaine is instilled before placing the strip in the lower fornix. I always dry the inferior fornix before doing either test. I think it is interesting to note that patients with meibomianitis will have copious tearing as the lack of oil from the lower lid allows the tears to flood the strip. I find that both of these tests are incorrect 30% of the time, so performing both reduces your chances of being fooled.

When my patient is only symptomatic with contacts in, then a trial of collagen implants is safe, easy and definitive of aqueous-deficient dry eye. I explain to the patients that contacts do not sit on the cornea but float on the tear film, which is why they are symptomatic with dry eyes and their feedback is crucial for the test to be effective.

Albert M. Morier, OD, is an instructor of clinical ophthalmology at Albany Medical College. He can be reached at Lion’s Eye Institute, Albany Medical College, 35 Hackett Blvd., Albany, NY 12208; (518) 262-2540; fax: (518) 452-8647; e-mail: amorier1@nycap.rr.com. Dr. Morier has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

Schirmer’s, fluorophotometry

William D. Mathers, MD: Primarily, I use the Schirmer’s test without anesthesia and consider it the most widely used and most easily interpretable test for diagnosing dry eye. The Schirmer’s strip should be pre-folded and placed in the lateral fornix. It is important to have the patient close his or her eyes during the test, as excessive blinking will definitely add a variable degree of excess stimulation. Care should be taken to avoid having the Schirmer’s strip touch the cornea for the same reason.

The test is easily performed and can be repeated frequently. However, repeating the test at close intervals probably won’t give reliable data because the Schirmer’s strip introduces irritation to the conjunctiva surface and would alter the baseline level of stimulation. I believe it’s important to do this test without anesthesia, because anesthetics decrease stimulation to the lacrimal gland in an unpredictable pattern. Schirmer’s test with anesthetic does not measure the steady state tear flow; it measures the tear flow in a partially anesthetized eye. If one truly blocks all stimulation from the ocular surface lids and lashes, tear flow would be absolutely minimal on all patients.

It’s important to keep in mind that Schirmer’s test results are strongly age dependent. A Schirmer’s test without anesthesia of 10 mm in a 20-year-old is abnormally low, but in an 80-year-old this is a relatively high value.

We also routinely use commercially available fluorophotometry to determine tear volume and tear flow. I find these tests to be particularly helpful in assessing steady state tear function. Great care must be used with the micropipette when applying the fluorescein to the bulbar conjunctiva. When this is done properly, almost no stimulation results. The test results are strongly influenced by the presence of punctal occlusion and by ectropion and other eyelid abnormalities.

Tear turnover, also derived from fluorophotometry, is our third most frequently used test. Data collected over a 20-minute period gives a very reliable measure of tear turnover. It is strongly affected by punctal occlusion but does not seem to be affected by age.

While each of these tests measures a different parameter, each has its contribution to an overall assessment of a dry eye patient. No one test is completely adequate. The more information one has on the dry eye patient, the more accurate the diagnosis can be made and the more appropriate the care of the patient.

William D. Mathers, MD, can be reached at Oregon Health Sciences University, 3375 SW Terwilliger Blvd., Portland, OR 97201-4197; (503) 494-3000; fax: (503) 494-3929; e-mail: mathersw@ohsu.edu. Primary Care Optometry News could not confirm whether Dr. Mathers has a financial interest in any of the products mentioned in this article, or if he is a paid consultant for any companies mentioned.

History diagnoses, exam tells why

Jeffrey P. Gilbard, MD: This is a trick question. Tests don’t diagnose dry eye; the history does. The exam then serves to determine why the patient has dry eye. Patients with dry eye complain of sandy-gritty irritation or burning in their eyes that gets worse as the day goes on. If a patient has this history, and the symptoms have been present for more than a few months, you know the patient has dry eye.

Patients can get dry eye by having either decreased tear production or increased tear film evaporation. In all of these patients, the tear film loses water, and tear film osmolarity increases. The increase in tear osmolarity causes the ocular irritation and surface damage these patients experience.

Production can decrease because of lacrimal gland disease (i.e., Sjögren’s syndrome) or through any disease or injury that decreases corneal sensation. This would include corneal surgeries such as laser in situ keratomileusis (LASIK), herpes simplex infections, diabetes and long-term contact lens wear, especially long-term hard contact lens wear.

Tear evaporation can increase from large palpebral fissure widths or meibomian gland dysfunction. Causes for large palpebral fissure width include large normal eyes, thyroid eye disease and blepharoplasty.

The exam then tells us why the patient has dry eye. Find out if there is a history of long-term hard contact lens wear or ocular herpes or diabetes or LASIK. Measure the palpebral fissure width by having the patient look right at your ipsilateral eye and measuring the span from lower lid margin to upper lid margin — widths of 10 mm or greater put evaporative stress on the tear film.

Examine the meibomian gland orifices — are they patent, stenosed or closed? Take a fluorescein strip, wet it with some sterile saline, shake off the excess, pull down the lower lid, then “paint” the strip along the inferior tarsal conjunctiva. With decreased tear volume the fluorescein won’t fluoresce. With meibomian gland dysfunction the tear film will look watery in quality. Finally, if indicated, touching the cornea with a fine cotton wisp can test corneal sensation.

Jeffrey P. Gilbard, MD, is the medical director of the Cornea & Vision Correction Center, clinical assistant professor at Harvard Medical School and founder and chief executive officer of Advanced Vision Research. He can be reached at Advanced Vision Research, 7 Alfred St., Ste. 330, Woburn, MA 01801; (781) 932-8327; Fax: (781) 935-5075; e-mail: info@theratears.com. Dr. Gilbard has no direct financial interest in any products mentioned in this article, nor is he a paid consultant for any companies mentioned.

Tear meniscus, lissamine green, Zone Quick

John L. Schachet, OD: In addition to a thorough history (which alerts you to potential dry eye problems even before you see the patient for the exam), I perform the following:

Tear Meniscus evaluation – With the biomicroscope, I evaluate the volume of the tear meniscus on a 0-4 scale. Although this is an objective test, it is very valuable in assessing why the conjunctiva may appear dry and injected.
Lissamine green test – This is used in place of rose bengal dye and is just as diagnostic and effective a dye as rose bengal, with the added benefit of not being irritating to the already dry eye. When either the conjunctiva or the cornea stains with the green dye, it indicates potential dry eye, possibly a mucin deficiency if the cornea is involved.
Zone Quick (phenol red thread test) – This simple test assesses the amount of tears present in the conjunctival sac, not the amount of tear production. However, we find this to be a greater indicator of the dryness of the anterior segment, and the test is not influenced by artificially wetting a strip like the Schirmer’s test. The Schirmer’s test may be influenced by reflex tearing or by the use of anesthesia, and neither of these problems occur with the Zone Quick test. It is very simple to read, and as a side benefit you have a permanent record of the test if you tape it to the patient’s record.

John L. Schachet, OD, is in private practice and is a former adjunct professor at the Southern California College of Optometry. He can be reached at Eyecare Consultants, 8586 E. Arapahoe Rd., Ste. 100, Englewood, CO 80112; (303) 771-4221; Fax: (303) 721-7759; e-mail: Jschachet@aol.com. Dr. Schachet has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.