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Advances have enhanced dry eye diagnosis, treatment
Dry eye can cause significant ocular discomfort in as much as one-third of the older population, although its impact on overall quality of life in those affected has often been underestimated. While the existence of the condition had been known for some time already, it was only recently that the etiology, diagnosis and treatment of dry eye have been systematized. As clinicians and the pharmaceutical industry are becoming increasingly interested in the disease, newer and more effective treatment options will soon be available for most patients.
The 2007 International Dry Eye WorkShop was a groundbreaking effort to better understand the evolution and pathophysiology of dry eye. It shed light on the importance of two hitherto unrecognized aspects of the condition: increased tear film osmolarity and ocular surface inflammation.
This has led to the development of instruments that measure tear film osmolarity and drops that offer “osmo-protection” to dry eye patients. Similarly, another device to measure the level of MMP-9 as a marker of ocular surface inflammation will soon be available to help quantify the presence of these changes. These newer diagnostic tests will, however, need to prove themselves in terms of clinical usefulness, availability and cost-effectiveness.
Treatments then and now
In the 1980s, treatment of dry eye was focused on replacing tear volume only, without enough emphasis on its quality. Polymers such as methylcellulose, which mimics the actual mucin present in human tears, have been the mainstay of dry eye treatment for more than 2 decades and are still in active use in many countries. Newer tear substitutes now consist of more complex molecules such as hyaluronic acid and carbomer-based lipids, which can help improve retention and protection of the ocular surface epithelium. They are often combined with organic solutes, which can help alleviate the deleterious effects of tear film hyperosmolarity.
One of the latest developments in tear substitutes is their ability to replace not only the inner mucin and the middle aqueous layers, but also the outer oily layer. Therefore, with the abundance of tear substitutes available on the market, physicians should understand their role and choose rationally for their patients. If ocular surface inflammation is considered to be a significant etiology, a course of topical steroids and/or cyclosporine A may be of value.
Local, systemic disorders
It is also becoming increasingly clear that dry eye is seldom a standalone disease, and it is frequently associated with many local or systemic disorders. Diligent search for local conditions such as blepharitis, meibomian gland dysfunction and systemic conditions such as Sjögren’s syndrome, rheumatoid arthritis, systemic lupus erythematosus, topical or systemic drugs use (eg, antihistamines and antidepressants) will help identify the contributing factors and may be amenable to treatment by helping to improve the ocular health and functions of such patients as well as their quality of life.
References:
The definition and classification of dry eye disease: report of the Definition and Classification Subcommittee of the International Dry Eye WorkShop (2007). Ocul Surf. 2007;5(2):75-92.
Khanal S, Tomlinson A, McFadyen A, Diaper C, Ramaesh K. Dry eye diagnosis. Invest Ophthalmol Vis Sci. 2008;49(4):1407-1414.
Research in dry eye: report of the Research Subcommittee of the International Dry Eye WorkShop (2007). Ocul Surf. 2007;5(2):179-193.
Su MY, Perry HD, Barsam A, et al. The effect of decreasing the dosage of cyclosporine A 0.05% on dry eye disease after 1 year of twice-daily therapy. Cornea. 2011;30(10):1098-1104.
For more information:
Dennis S.C. Lam, MD, FRCOphth, can be reached at Hong Kong Eye Hospital, The Chinese University of Hong Kong, 3/F, 14K Argyle Street, Kowloon, Hong Kong, SAR, China; +011-852-2762-3157; fax: +011-852-2715-9490; email: dennislam8@cuhk.edu.hk.
Disclosure: Drs. Fan, Rao and Lam have no relevant financial disclosures.