dry eye

Getting a Grip on Chronic Dry Eye

Choosing the best treatment requires thorough diagnostics and the recommendation of therapies with proven results.

ERNEST L. BOWLING, O.D., M.S., F.A.A.O., DIPL., Summerville, Ga.
GREGG ERIC RUSSELL, O.D., F.A.A.O., DIPL.
Marietta, Ga.

For most of the 11% to 22% of the U.S. population who suffer from chronic dry eye, uncomfortable or even unbearable symptoms are constantly present.¹ To effectively provide relief for these patients and break the cycle that progressively damages the ocular surface, you must take a comprehensive approach to diagnosis and treatment.

Such an approach, however, is confounded by several factors, including that dry eye takes many forms clinically, and no definitive rules for diagnosis and treatment exist.

Furthermore, in each individual patient, the condition can change — worsen or improve — based on changes in the patient's life and how well treatment is working. (See "The Importance of Frequent Follow-Up," below.)

Thankfully, our ability to successfully manage chronic dry-eye patients has been aided by the work of the International Dry Eye WorkShop (DEWS). In its 2007 report, DEWS established a significantly updated definition of dry eye.² The DEWS editorial board no longer considers the condition as simply a case of poor tear-film quality or quantity. Instead, they define dry eye as "a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance and tear-film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface."

This new definition is important because it encourages us to look at the big picture in our efforts to recommend the best therapy for each of our chronic dry-eye patients. In this article, we explain the latest thinking on how to accomplish this.

Zero in on each patient's situation

Chronic dry-eye sufferers can experience a variety of symptoms, including burning, stinging, photophobia, ocular dryness, grittiness, blurred vision and foreign-body sensation. These symptoms can be due to many different causes. For example, autoimmune conditions, such as rheumatoid arthritis, Sjogren's Syndrome, rosacea and Stevens-Johnson syndrome, are often associated with dry eye.

Hormones can influence the occurrence of dry eye as well, as seen in the increased prevalence of chronic dry eye in post-menopausal women.³

In addition, other factors, such as the environment, can play a role. Wind, low humidity in a home or during air travel and exposure to dust and animal dander can exacerbate symptoms.^4,5

Contact-lens wear can also be a culprit.⁶ Previous ocular surgery, including LASIK and medications containing drying compounds (i.e. systemic antihistamines and antidepressants) are also linked with dry eye.^6,7

Because of the multitude of potential underlying causes of chronic dry eye, you must capture a comprehensive medical history, environmental history and medication profile to best understand a patient's case. Probing the patient's symptoms may reveal any relation to visual tasking and environmental circumstances in daily life. The use of symptom or lifestyle questionnaires to assess the interaction between symptoms and daily activity can help you to understand a particular patient's disorder.

In some cases, simply advising patients to avoid triggers, such as allowing pets in their beds, can reduce dry-eye symptoms. Also, lagophthalmos awareness and evaluating lid tonus can uncover a prelude to daily discomfort.

Match the treatment to the diagnosis

While researchers investigate new therapeutic agents targeted at specific layers of the tear film, such as mucin secretagogues, artificial tear substitutes continue to serve as the first-line treatment for most dry-eye patients.

Ultimately, it's imperative you recommend tear substitutes that have proven clinical results in improving the signs and symptoms of dry eye. You must also keep in mind that the interaction of symptoms with clinical signs of dry eye differs throughout the dry-eye population.⁸

Because dry-eye patients can present with various combinations of symptoms or complain of no symptoms, and several artificial tears only temporarily relieve symptoms, you must assess clinical signs thoroughly.⁹ You can then select the appropriate artificial tear and add additional therapies when necessary.

Several diagnostic tools can help you to determine and treat the severity of each patient's disease. We recommend: the following:

■ Tear Film Break-Up Time (TFBUT). Complete and repetitive blinking spreads the tear film across the ocular surface.

To determine how long it takes for the tear film to "decay," or break up, after the blink, instill a microdrop of sodium fluorescein into the eye. After a complete blink, measure TFBUT at the slit lamp utilizing either a video-capture system, a stopwatch or simply count the seconds until a dark spot or spots appear on the cornea. It is generally accepted that a TFBUT of less than seven seconds indicates a possible problem, and anything less than five seconds indicates significant dry eye.

To provide therapy for a patient who exhibits a shortened TFBUT, look for tear substitutes that increase the break-up time.

■ Ocular Protection Index (OPI). The interaction between blinking and tear-film integrity is important for maintaining ocular-surface protection. By determining the ratio of TFBUT to inter-blink interval (IBI), we can determine the OPI, or average level of ocular surface protection.

To calculate OPI, count the number of times per minute the patient blinks while reading the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart. Divide 60 by the number of blinks per minute to calculate the IBI. Measure the TFBUT, and divide it by the IBI to obtain the OPI score.

An OPI score of less than 1.0 indicates that the ocular surface is insufficiently protected from environmental harm. An OPI score greater than or equal to 1.0 indicates the ocular surface is adequately protected.

For patients whose OPI score is less than 1.0, recommend an artificial tear that has been shown to increase OPI.

■ Staining. When tear-film break-up repetitively occurs before a blink can replenish the tear film, the ocular surface is left exposed to environmental harm. This exposure, when consistent, leads to epithelial-cell desiccation. Fluorescein and lissamine-green staining allows you to evaluate damage on the cornea and conjunctiva, respectively.

To treat patients who have staining consistent with dry eye, recommend an artificial tear that produces a significant reduction in staining and promotes epithelial repair.

When artificial tears alone aren't enough

Given the nature of their condition, chronic dry-eye patients often require therapy in addition to artificial tears. Prescription cyclosporine ophthalmic emulsion 0.05% (Restasis, Allergan) reduces the inflammation and itching associated with chronic dry eye by selectively supressing T-cells.¹⁰

Surface and intracanalicular punctal plugs are also an important tool when treating chronic dry eye, as they help build the tear reservoir and improve ocular comfort.^11,12

Punctal plugs may not be a good first choice for patients who have issues with tear-film quality due to inspissated meibomian glands or consistently poor lid closure on blink. In addition, you must consider the position of the puncta when choosing the device to insert. If the puncta is rolled back across the corneal surface, intracanalicular plugs may work better than other plugs. If the punctal opening is tangential to the lid surface, a surface plug should be adequate.

Ointments can be helpful for our chronic dry-eye patients as well, especially when lagophthalmos is present.

In addition, the medical literature has shown that steroid drops decrease ocular-surface inflammation markers and improve the subjective comfort of dry eye.¹³ Indeed, it has become commonplace to utilize steroids in patients concurrently treated with cyclosporine ophthalmic emulsion 0.05% b.i.d.

Furthermore, because the medical literature has revealed that omega-3 fatty acids benefit dry-eye patients, we regularly recommend an increase in dietary-intake of omega-3 fatty acids to our dry-eye patients.¹⁴

Finally, in cases in which dry eye is accompanied by meibomian gland dysfunction, we may also prescribe doxycycline.

Stay on top of quality-of-life issues

When treating chronic dry-eye patients, you obviously want to effectively manage the clinical signs. But, you must also pay attention to and address your patients' quality-of-life issues and the tolerability of treatment.

For example, if a patient complains of lid caking or sensitivity to an artificial tear (perhaps due to a preservative), you may want to switch the patient to a different product.

See the whole picture

To choose the most successful treatment, or treatments, for your chronic dry-eye patients, clinical signs, subjective symptoms, tolerability and relevant research all must play a role. Prudent recommendations result from good data and a comprehensive approach. OM

1. Brewitt H, Sistani F. Dry eye disease: the scale of the problem. Surv Ophthalmol 2001 Mar;45 Suppl 2:S199-202.
2. 2007 Report of the International Dry Eye WorkShop (DEWS). Ocul Surf 2007Apr;5(2):65-206.
3. Schaumberg DA. Epidemiology of dry eye disease. Presented at: Tear Film and Ocular Surface Society Meeting 2007, Taormina, Sicily.
4. Gonzalez-Garcia MJ, Gonzalez-Salz A, de la Fuente B, et al. Exposure to a controlled adverse environment impairs the ocular surface of subjects with minimally symptomatic dry eye. Invest Ophthalmol Vis Sci 2007Sep;48(9):4026-32.
5. Uchiyama, E, Aronowicz JD, Butovich IA, McCulley JP. Increased evaporative rates in laboratory testing conditions simulating airplane cabin relative humidity: an important factor for dry eye syndrome. Eye Contact Lens 2007Jul; 33(4): 174-6.
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9. Abelson MB, Ousler GW, Nally LA, et al. Alternative reference values for tear film break-up time in normal and dry eye populations. In: Sullivan DA, Stern ME, Tsubota K, et al., eds. Lacrimal Gland, Tear Film, and Dry Eye Syndromes. Vol 3. New York, NY: Kluwer Academic/Plenum Publishers; 2003.
10. Sall K, Stevenson OD, Mundorf TK, Reis BL. Two multicenter, randomized studies of the efficacy and safety of cyclosporine ophthalmic emulsion in moderate to severe dry eye disease. Ophthalmology 2000 Apr;107(4):631-639.
11. Roberts CW, Carniglia PE, Brazzo BG. Comparison of topical cyclosporine, punctal occlusion, and a combination for the treatment of dry eye. Cornea 2007Aug;26(7):805-809.
12. Hamano T. Lacrimal duct occlusion for the treatment of dry eye. Seminars in Ophthalmology 2005 Apr-Jun;20(2): 71-74.
13. Avunduk AM, Avunduk MC, Varnell ED, Kaufman HE. The comparison of efficacies of topical corticosteroids and nonsteroidal anti-inflammatory drops on dry eye patients: a clinical and immunocytochemical study. Am J Ophthalmol 2003 Oct;136(4):593-602.
14. Miljanović B, Trivedi KA, Dana MR, et al. Relation between dietary n-3 and n-6 fatty acids and clinically diagnosed dry eye syndrome in women. Am J Clin Nutr. 2005 Oct;82(4):887-93.

Dr. Bowling is an associate professor and director of the primary eyecare service at the University of Alabama at Birmingham School of Optometry. E-mail him at ernie50@uab.edu. Dr. Russell practices at the Marietta Eye Clinic. He specializes in contact-lens fittings for patients who have keratoconus, corneal scars and refractive surgery complications. Contact him at (770) 427-8111.