Optometric Management Supplements

Dry Eye 2017

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O ne of the most significant discoveries related to the diagnosis and management of dry eye has been that evaporative dry eye caused by mei- bomian gland dysfunction (MGD) is likely far more prevalent than dry eye caused by tear deficiency. In one study, Lemp and colleagues found that among patients diagnosed with dry eye in 10 clinics in the European Union and the United States, 86% demonstrated signs of MGD. 1 Like dry eye disease, MGD is a complex entity, and the two are intertwined in the same cycle that, without appropriate treatment, can lead to ocular surface damage. THE PATHOPHYSIOLOGY OF MGD One of the pathophysiological mechanisms common to both dry eye and MGD is inflammation. Inflammation leads to tissue scarring, which causes lacrimal gland dysfunction and decreased aqueous tear production. But inflammation and tissue scarring also lead to MGD and goblet cell dysfunc- tion, both of which can create a defective tear film lipid layer, in turn causing increased evaporative tear loss (Figure 1). Five physiological mechanisms of MGD are known: eyelid inflammation, conjunctival inflammation, corneal damage, microbacterial changes, and dry eye from tear instability. 2 Clearly, MGD is multifactorial, and these factors tend to be cumulative. For example, MGD can begin with microbial changes at the lid margin, which initiates a self-stimulating cycle (Figure 2). Bacterial changes lead to hyperkeratini- zation and an increase in the melting temperature of the meibum, which leads to gland blockage and eventual mei- bomian gland dysfunction. With the glands compromised, tear instability, hyperosmolar tears, and inflammation ensue. TREATING MEIBOMIAN GLAND DISEASE LipiFlow (TearScience) is the first device approved by the FDA for the treatment of MGD. I've used this 12-minute procedure as part of treatment for about 100 patients and have achieved good results. Many patients have described the treatment as "spa-like." One study that pertains to patient selection for LipiFlow is worth mentioning. e purpose of the study was to determine if meibography can predict meibomian gland function in patients with symptoms of dry eye (based on the SPEED questionnaire). 3 e researchers per- formed meibography using the Modi topographer and Phoenix software (s4optik) and measured gland function and estimated functional gland volume using the Korb Meibomian Gland Evaluator (TearScience). ey found that the nasal and central sections of the lower eyelid contained the highest average number of glands and significantly more functional glands and higher func- 8 JANUARY 2017 A Big Piece of the Dry Eye Puzzle If you're not addressing meibomian gland dysfunction, you're not addressing dry eye By Whitney Hauser, OD Figure 1. Inflammation plays a role in both tear-deficient and evaporative dry eye disease. MGD and Inflammation Inflammation as an underlying factor in the pathophysiology of dry eye syndrome 1-3 Tissue Scarring Meibomian Gland/ Goblet Cell Dysfunction Defective Tear Lipid Film/Layer Increased Evaporative Loss Decreased Aqueous Tear Production Lacrimal Gland Dysfunction Inflammatory Cellular Infiltration

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