Focus on … dry eye disease introduction

Introduction to dry eye disease

Opportunities now for the registered dispensing optician (DO) are many and varied, far from being the role we all took on when we were doing our initial training, the DO of today may well be involved in practice (or area/regional) management in an independent, group or chain setting. Alternatively, they may have chosen to go down a more clinical route and further qualify in spectacle lens design, LVAs or contact lenses and punctal plugging.

Further study may lead to qualification as a contact lens optician (CLO) and further accreditation within extended services; Minor Eye Conditions (MECS), Covid-19 Urgent Eyecare Service (CUES) and Glaucoma Repeat Measure (GRM). Maybe the interest is working in specific areas such as paediatric clinics or those with learning difficulties, or services supporting cataract and glaucoma, and for some it might be opportunities within the hospital eye service or independent service providers. It may be that it is the industry, rather than the profession, that provides another direction for some to explore.

Whichever route through this wonderful profession is chosen it is highly likely that the subject of dry eye disease (DED) will be something that everyone experiences to some degree or other and like any other ocular condition the DO should be in a position to recognise its presence and provide or recommend appropriate care to the patient.1,2

Dry eye disease affects hundreds of millions of people worldwide and is one of the most common causes of patient visits for eye care, yet it remains largely under or mis-diagnosed and worse, untreated often due to an underlying lack of understanding.

The work of the Tear Film and Ocular Surface Society (TFOS) to create the TFOS Dry Eye Workshop (DEWS) report 2007 and more recently TFOS DEWS IITM 2017, from which much of the content here is taken, has made great inroads into achieving global standards regarding the definition and classification of DED, understanding of the epidemiology, mechanism and impact of the disease, and perhaps most relevant to clinical practice, the diagnosis, management and therapy of DED.3  The author highly recommends the further reading available at

Brief reminder of the structure and function of the tear film

The importance of a stable tear film is recognised for many reasons. It is the first refracting surface for incident light entering the visual system, as well as the protective, moisturising and nutritional roles. The traditional three layer “sandwich” structure of the tear film has now been redefined as an extraordinarily thin (2-5.5 μm) modified two-layer structure, an outer lipid layer produced by the meibomian glands, overlying a muco-aqueous phase, produced by the lacrimal gland, accessory lacrimal glands and the goblet cells of the conjunctiva4. The main role of the lipid layer is understood to help prevent evaporation of the preocular tear film by lowering the surface tension at the air interface.

The currently accepted volume of a “normal” tear film is approximately 8 μl.

Read more about dry eye disease

  1. Introduction, role of the dispensing optician
  2. Definition and classification of dry eye disease
  3. Pathophysiology
  4. Prevalence and epidemiology
  5. Diagnosis
  6. Assessment
  7. Management
  8. Education
  9. References and further reading