I was pleased to accept an invitation to give a lecture at the Australian College of Optometry in June 2017, discussing ocular surface disease and dry eye disease. My talk, entitled Dry Eye Disease: Smooth Sailing of the Lacrimal Rivus, reviewed the anatomy and physiology of the lacrimal functional unit, highlighting the constituent layers of the tear film and the epidemiology and pathophysiology of dry eye disease. Dry eye disease affects 337 million people worldwide, with prevalence estimates ranging from 5 to 30 percent, depending on the definition of dry eye disease. It can affect everybody, but is more common in females, the elderly, and in those of asian and hispanic ancestry.
I summarised my therapeutic approach to dry eye disease and commented on new technologies in the diagnosis and treatment of this complex condition. I highlighted tear hyperosmolarity and tear film instability as the core mechanisms of dry eye disease, and described how these cause inflammation and damage to the ocular surface.
The importance of dry eye disease in patients undergoing cataract surgery can not be overemphasised. I discussed some of the results from the Prospective Health Assessment of Cataract patients Ocular surface study (PHACO study), pointing out that many patients who are planning of having cataract surgery have significant dry eye disease that can negatively impact their outcome. This study showed that 77% of patients who were scheduled to have cataract surgery had corneal fluorescein staining, and 63% had reduced tear break up time. Both corneal staining and reduced tear break up time are diagnostic signs of dry eye disease that can cause errors in the measurements for intraocular lenses and can lead to poor outcomes. It has been shown that treating dry eye disease before cataract surgery measurements are done can reduce the risk of infection, improve the accuracy of the measurements, improve refractive outcomes, and increase patient satisfaction.
I also discussed the impact of dry eye disease on corneal refractive surgery, including LASIK and PRK. It is known that corneal refractive surgery causes altered corneal sensation leading to disruption of the tear reflex and the lacrimal functional unit. The corneal nerves and corneal sensation recover more quickly after PRK compared to LASIK, making it a better choice in patients who suffer from dry eye disease. It is very important to diagnose dry eye disease before considering corneal refractive surgery to ensure the appropriate procedure is selected.