Dr Marsha Oberholzer recently presented a webinar on dry eyes. This was sponsored by Pharmaco. The following is a summarised version of her presentation. 

To watch a replay of this webinar and still earn a CPD point, go to: https://event.webinarjam.com/replay/792/ q7647f635h1wquxowsyw1r. Email john.woodford@newmedia.co.za to let him know to allocate your point/ request an attendance certificate for those who don’t fall under the HPCSA. 

Dry eye disease (DED) is a complex and multifaceted condition that significantly impacts patients' quality of life. It is characterised by a loss of homeostasis of the tear film, leading to ocular symptoms such as dryness, irritation, and potential damage to the ocular surface. The tear film itself is a sophisticated structure composed of three primary layers: the lipid layer, aqueous layer, and mucous layer. Recent advancements in our understanding of the tear film have shifted the perspective from viewing these layers as distinct entities to recognising them as a single dynamic functional unit. This article explores the dry eye wheel, a conceptual framework that aids healthcare professionals in the mitigation, measurement, and management of dry eye disease.  

Reimagining the tear film  

Historically, the tear film was perceived as a series of separate layers. However, contemporary research indicates that it functions as a gradient of aqueous through mucins, forming a viscoelastic gel with a lipid bilayer on the surface. The total thickness of the tear film is approximately 2-6 micrometres, with variations influenced by factors such as reflex tearing. The lipid layer, primarily composed of triglycerides, free fatty acids, and phospholipids, plays a crucial role in reducing evaporation and maintaining tear stability. Rheological studies have demonstrated that the tear film exhibits non-Newtonian shear-thinning behaviour, meaning its viscosity decreases with increased shear rates, such as during blinking. This dynamic nature is essential for the tear film's protective and lubricating functions.  

The dry eye wheel: a comprehensive framework  

The dry eye wheel serves as a comprehensive model for understanding the various aspects of dry eye disease, including its mitigation, measurement, and management.  

1. Mitigation: This aspect focuses on identifying and addressing risk factors associated with dry eye disease. Factors such as environmental conditions, screen time, and contact lens wear can exacerbate symptoms. Education on lifestyle modifications, such as increasing humidity in living spaces and taking regular breaks from screens, can help mitigate the impact of dry eye. 
2. Measurement: Accurate assessment of dry eye disease is crucial for effective management. Various clinical tools and questionnaires are available to evaluate symptoms and signs of dry eye. The ocular surface disease index (OSDI) and the dry eye questionnaire (DEQ) are commonly used to assess patient-reported outcomes. Additionally, objective measures such as tear break-up time (TBUT) and osmolarity testing can provide valuable insights into the severity of the condition. 
3. Management: The management of dry eye disease is multifaceted and may include pharmacological and non-pharmacological interventions. Artificial tears and lubricating eye drops are often the first line of treatment. In more severe cases, prescription medications such as cyclosporine A or lifitegrast may be indicated. Punctal plugs can also be utilised to reduce tear drainage and enhance tear film stability. Advanced therapies, such as intense pulsed light therapy, have shown promise in treating meibomian gland dysfunction, a common cause of
   evaporative dry eye.

The interplay of physical and social factors  

Physical health factors, such as obesity and physical inactivity, have been linked to dry eye disease. Obesity can lead to structural changes in the meibomian glands, which are essential for producing the lipid layer of the tear film. Furthermore, conditions such as obstructive sleep apnoea may exacerbate dry eye symptoms.  

Social factors, including smoking and exposure to environmental irritants, also play a role in the development and exacerbation of dry eye disease. While smoking rates are declining globally, the association between smoking and dry eye remains a topic of interest. Recent studies suggest that vaping may also contribute to dry eye symptoms, necessitating further research in this area.  

The patient experience: a spectrum of symptoms  

Patients with DED often report a range of symptoms, including burning, irritation, dryness, stinging, and fatigue. However, the experience of these symptoms can vary widely among individuals.  

This variability underscores the importance of a patient-centred approach in clinical practice. Understanding the individual’s perspective on their symptoms and how these affect their daily life is crucial for effective management. Factors such as age, occupation, psychological traits, and personal habits can all influence how patients experience and cope with DED.  

Conclusion  

The dry eye wheel provides a valuable framework for understanding the complexities of dry eye disease. By addressing the multifactorial nature of the condition, healthcare professionals can develop comprehensive management strategies that improve patient outcomes. As our understanding of the tear film and its dynamics continues to evolve, it is essential to remain vigilant in recognising the real-world impact of dry eye disease on patients' quality of life.  

A multidisciplinary approach that encompasses ocular health, mental well-being, and lifestyle factors will be crucial in effectively managing this prevalent condition. By prioritising patient education, accurate measurement, and personalised management strategies, healthcare professionals can significantly enhance the quality of life for individuals suffering from DED.