ANNUAL DRY EYE REPORT
2009 Annual Report on Dry Eye Diseases
A review of research findings and results from a dry eye survey provide insight into current dry eye knowledge.
By Jason J. Nichols, OD, MPH, PhD, FAAO
Dr. Nichols is an assistant professor of optometry and vision science at The Ohio State University College of Optometry. He has received research funding from Alcon, CIBA Vision, and Vistakon.
Dry eye diseases seem ubiquitous these days; we all have patients who suffer tremendously from these conditions. Dry eye diseases are among the most prevalent ophthalmic conditions seen by eyecare practitioners (Lemp, 2009; Smith, 2007). Furthermore, the frequency of dry eye in contact lens wearers seems disproportionately higher than in non-lens wearers.
There is significant interest in the pharmaceutical treatment of dry eye disease, with agents targeted at treating the condition from several companies in clinical trials.
Thus, it is critical that we diligently focus our efforts on understanding dry eye diseases so we can continue to optimally care for our patients. The purpose of this report is to summarize some of the current knowledge of dry eye conditions, as well as to evaluate management trends for the conditions.
Understanding Dry Eye
We've made significant progress in understanding dry eye conditions over the past 15 years. In the early 1990s, the National Eye Institute/Industry sponsored workshops to determine the current state of affairs in dry eye disease. In 1995, the CLAO Journal published a 12-page report that summarized these workshops.
More recently, the Tear Film and Ocular Surface (TFOS) Society sponsored a series of workshops to provide a more contemporary consensus on the current state of dry eye disease (similar to the way the National Eye Institute/Industry sponsored workshops in the early 1990s). The report was published in The Ocular Surface in 2007 (available for free at http://www.tearfilm.org/dewsreport/), and contains more than 100 pages of material. Table 1 details the area chapters within the report.
Defining Dry Eye
It is important that we begin our discussion with an overview of the current definition of dry eye, as well as to highlight some differences in the way this definition has changed in the more recent DEWS report. The 1995 report developed the following definition of dry eye:
Dry eye is a disorder of the tear film due to tear deficiency or excessive evaporation, which causes damage to the interpalpebral ocular surface and is associated with symptoms of ocular discomfort.
In the 2007 report, the definition of dry eye was modified as follows:
Dry eye is 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.
Figure 1. For every 100 non-contact lens patients, the number that had some form of dry eye disease (n=464).
Note that the definitions are similar in that they both acknowledge the role of symptoms (patient discomfort) and ocular surface damage. However, several differences should be highlighted. First, the original definition distinguished between tear (aqueous) deficiency and evaporation, while the new definition does not. Although these terms were removed from the definition, the classification scheme still maintains this distinction. A second major change is the recognition of the visual impact of dry eye in addition to the role of tear instability. But the largest difference between the definitions comes in the second sentence of the new definition. Specifically, both osmolarity and inflammation are recognized as being associated with dry eye (they are recognized as an association rather than as a cause).
Relative to the first point above, it is important to emphasize that the DEWS report maintains an overall classification scheme that includes the tear (aqueous) deficient and evaporative etiologies of dry eye disease. The tear (aqueous) deficient etiology scheme is further broken down into Sjögren's and non-Sjögren's dry eye (lacrimal deficiency, lacrimal gland duct obstruction, reflex block, and systemic drug-induced). The evaporative etiology includes intrinsic (meibomian oil deficiency, lid aperture disorders, altered blink rate) and extrinsic (vitamin A deficiency, topical drug preservatives, ocular surface disease, and contact lens wear) causes. Thus, contact lens wear maintains an "evaporative" etiological classification, as it did in the original 1995 NEI/Industry Report.
Overview of Dry Eye Trends: Survey Results
In March and April 2009, we initiated a survey of our readership designed to track important trends in dry eye and contact lens dry eye. The survey covered a range of topics including frequency estimates of some key dry eye conditions, methods of diagnosis, treatments for dry eye and contact lens dry eye, and business aspects related to caring for dry eye patients. In total, 467 respondents completed the survey. Many of the results were quite interesting and certainly relevant to your practice. The next sections detail those results.
Dry Eye Frequency, Severity, and Etiology (Non-Lens Wearers)
As mentioned previously, dry eye disease is thought to be one of the most frequent conditions that eye-care practitioners manage. Depending on the geographic location, definition, and age of the sample being studied, true population-based studies have estimated prevalences of dry eye ranging from 5.5-to-33.7 percent. Our survey asked for your impressions on the frequency of dry eye in your practices. On average, you stated that out of every 100 non-contact lens patients you examine, about 34 percent (±21 percent) have some form of dry eye disease. Figure 1 shows the overall distribution, in which you'll see the majority of responses (57 percent) fell in the range of 30 percent or less of dry eye patients. This seems consistent with the aforementioned population-based study results.
Relative to the severity of dry eye in the patients you manage, you reported the vast majority to have mild (50.2 percent) or moderate (48.7 percent) dry eye, while only a small fraction are considered severe (1.1 percent). Relative to making the actual dry eye diagnosis, most of you prefer to use a symptom assessment (28 percent) or tear breakup test (27 percent). This corresponds well with prior research showing that most of you indeed prefer and actually use these two assessments most commonly in making your diagnosis.
Figure 2. Preferred dry eye diagnosis method (n=463).
Figure 3. Most frequently used treatment for dry eye disease (n=449).
The literature is sparse relative to the actual breakdown of so-called tear (aqueous) deficient dry eye and evaporative dry eye (e.g., blepharitis). Thus, our survey asked questions specifically targeted at etiological distinctions of dry eye. Interestingly, for every 10 non-contact lens wearing patients who have dry eye that you examine, you believe that, on average, 4.2 (±2.4) patients have evaporative dry eye while 3.4 (±2.1) have tear (aqueous) deficient dry eye. So, it seems that slightly more of your dry eye patients have evaporative dry eye than aqueous deficient dry eye.
Managing Dry Eye
Managing dry eye disease today is a challenge, as no one therapy is necessarily completely efficacious. This may result from the multifactorial nature of dry eye, with different associated etiologies. However, there is unquestionably a tremendous amount of clinical and research activity in this regard, so the future looks promising.
Figure 3 shows the distribution of the various treatments our survey respondents use for dry eye disease. As you might expect, the use of artificial tears in managing dry eye conditions is what you reported to be your most frequent treatment associated with the disease; most of you (59 percent) use preserved drops more frequently than unit-dosed (non-preserved) artificial tears.
It's slightly surprising that the use of other treatments (such as Restasis, Allergan) were not reported with higher frequencies. The survey did not ask for your rationale for your treatments, although this will be important for us to consider in the future.
We also asked about the financial aspects related to managing dry eye disease. The overall gross revenue associated with managing dry eye disease per respondent was 11 ±11 percent while the overall net revenue associated with managing dry eye disease per respondent was 9 ±10 percent. When asked about predicting future business associated with managing dry eye disease over the next year 67 percent of you thought your business associated with dry eye would be "increasing," while 33 percent of you thought your dry eye treatment business would be "staying the same."
Contact Lens Dry Eye Frequency, Severity, and Etiology
Most practitioners who manage contact lens patients know that discomfort and dryness are common complaints associated with lens wear. In fact, again depending on the definition of dry eye, studies have estimated the frequency of dry eye in contact lens wearers to range from 25 percent to 75 percent. Thus, our survey also asked questions pertaining to dry eye in contact lens wearers.
According to our survey, for every 100 contact lens wearers you examine, approximately 34 percent (±21 percent) have mild dryness/discomfort, while about 10 percent (±10 percent) have severe dryness/discomfort. Thus, in total, you reported that about 45 percent of your patients have contact lensrelated dry eye.
We also asked about time of day, because prior research has indicated that symptoms may worsen over the course of a day's wear of contact lenses. Indeed, our survey shows that this appears to be the case. As Figure 4 demonstrates, 89 percent of you feel that your patients experience the most dryness/discomfort at the end of the day.
Figure 4. Time of day when eye comfort during contact lens wear is the worst (n=441).
Managing Contact Lens-Related Dry Eye
Our survey specifically asked about respondents' management/treatment approaches for patients who have contact lens-related dry eye. Figure 5 presents the results. When asked about the "one most common treatment" you use for dry eye in your contact lens wearers, nearly half (49 percent) said that your overall preference was to refit patients into a different material. This was followed by recommendation of a rewetting drop (21 percent), and changing the care solution (12 percent).
Figure 5. Most commonly used treatment for dry eye in contact lens wearers (n=439).
We also asked as a follow-up question what you use as your "second most common" treatment for dry eye in lens wearers. When asked this, the three most frequent treatments remained the same as the "one most common treatment," but changing the care solution moved to the top of the list (25 percent), followed by rewetting drops (23 percent), and refitting into a different lens material (21 percent). Other response choices for those two questions remained in approximately the same frequency (which was low) and order of usage.
Relative to the finding that refitting into a different lens material was the most preferred treatment for contact lens-related dry eye, we asked in a follow-up question what material characteristic you felt is most efficacious in reducing dryness/discomfort. As Figure 6 shows, respondents overwhelmingly felt that refitting into a silicone hydrogel (planned replacement) lens was the most beneficial (53 percent of responses), followed by the use of daily disposable lenses (29 percent of responses). You reported using general low-water-content and high-water-content lens materials (both non-silicone hydrogel) in low frequencies when working with patients who have contact lens-related dry eye. We also asked whether GP lens materials offered general comfort benefits compared to soft contact lenses, and an overwhelming 81 percent of you said that they do not.
Figure 6. When refitting into a different lens material, what general category listed do you feel is most efficacious at reducing dryness/discomfort? (n=438).
There is still a tremendous amount that we do not understand about dry eye conditions. For example, we still don't exactly understand the true biochemical composition of the meibum or tears themselves. Further, the lack of correlation between clinical signs and symptoms in dry eye conditions continues to stymie clinicians. Lastly, although we've made great strides in understanding and treating meibomian gland diseases, we still have a long way to go in this regard.
But the future does indeed look bright relative to the vast number of clinicians and scientists working to unravel these important mysteries, and much active research continues to be undertaken. CLS
To obtain references for this article, please visit http://www.clspectrum.com/references.asp and click on document #164.