Definition
The original DEWS report definition was the first-time dry eye was identified as a disease, with many underlying causes, that was deemed to result in symptoms and signs, in association with tear film hyperosmolarity and ocular surface inflammation.
The latest definition from DEWS II is as follows:
Dry eye is a multifactorial disease of the ocular surface characterised by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles.
Based upon this definition, it is clear that understanding the nature of any individual dry eye disease presentation and attempting a tailored approach to management requires the practitioner to look at a number of presenting signs and measurements in order to help the patient in future.
History
The best diagnostic work up begins with a good history, and the assessment of possible dry eye disease is no exception. Although the relationship between signs and symptoms is variable between individuals, assessing symptoms accurately allows decisions to be made regarding whether further evaluation is important, as well as monitoring response to treatments. Dry eye questionnaires exist to aid the specific diagnosis of dry eye disease and grade the severity to set a baseline for future reference. The OSDI (Ocular Surface Disease Index) is the most widely used
Clinical tests
Once symptoms have been assessed, the following are all important:
- Non-invasive tear break-up time (NITBUT)
- Osmolarity
- Fluorescein break up time (FBUT) if not NITBUT
- Ocular surface staining
Further tests to inform about the sub-type of a presentation include:
- Meibomian gland imaging (meibography), observation and expression
- Lipid layer thickness measurement
- Tear volume measurement
Management
The TFOS DEWSII states, ‘Management is ultimately aimed at restoring the homeostasis of the ocular surface by breaking the vicious cycle of the disease and offering long-term options to prevent a return to the vicious cycle and a resurgence of symptoms.’
Staged management
The basis of effective management begins with accurate diagnosis. It is important to categorise an individual’s dry eye disease in terms of the degree to which EDE, ADDE and any other ocular surface conditions are contributing to the overall picture for that patient. The concept of determining the major causitive factor is key to appropriate and effective management. While there are treatments which are indicated for multiple aspects of DED, others are specific to one particular aspect of an individuals ocular surface condition.
The steps outlined in figure 1 show the most evidence-based staged management of DED depending on severity. The exact nature of an individual’s DED will dictate the range and number of management options selected from one or more steps.
Figure 1: The DEWS II approach to managing DED. Once the working differential diagnosis and disease severity has been reached, the treatment plan can be developed