Dry eye and myopia management - Q&A with Sarah Farrant

I can safely say that I feel it is essential to assess the ocular surface full stop.  As a clinician I would never feel that I had sight of the bigger picture of a patient’s baseline information without a good understanding of the state of the ocular surface, given it is the foundation upon which any form of contact lens intervention will stand. Children are known to report dry eye symptoms less frequently than adults, so even when asymptomatic it is important to screen for it.¹ In addition, roughly 10% of children have some form of hay fever² or allergy, and most have ocular symptoms. Symptoms of dry eye disease can sometimes be confused with asthenopia and poor binocular vision – an important differential in a child.³ A poor tear film is also known to influence the accuracy of topography data.⁴ Epithelial cells can change the shape of the cornea as they dry out or are lubricated. The prevalence of dry eye disease in children ranges between 5%-23%.⁵ We are also sadly seeing a rise in prevalence of ocular surface disease in patients including children potentially related to modern lifestyle factors such as increased screen use and environmental triggers (TFOS lifestyle report). Interestingly, related to this, one study showed children who had great outdoor time had far less dry eye disease.⁶

Given the now wider than ever variety of myopia management interventions, it is possible to tailor one’s clinical choice more precisely to the individual needs of the patient so that any allergy or dry eye disease can be considered. When considering options implicating the ocular surface, we should also be aware of the potential long-term risk to the Meibomian glands from contact lenses.⁷ Often it is appropriate to formulate a tailored management plan, not only for the myopia but also to optimise the ocular surface in preparation for such a strategy. I might in practice, for example, choose orthokeratology over daily contact lenses in a case of dry eye disease but may select a daily contact lens in an allergy sufferer given the known protective effect of contact lens wear in hay fever.⁸     

The MYAH enables rapid data gathering of biometry, topography, and a number of informative ocular surface paradigms. Whilst offering the more commonly understood assessment of blink rate, tear meniscus height (see figure 1), non-invasive tear break up time (NITBUT), and Meibomian gland analysis using meibography, the data also assesses Inter-Blink Interval (IBI) and Ocular Protection Index (OPI) (see figure 2). IBI is an average measure of the average interval between blinks. OPI relates this to the NITBUT and calculates the risk to the ocular surface of dry eye disease based on the likelihood of the blink being longer than the break-up time. OPI less than 1 is an ocular surface at risk of symptoms and damage. OPI greater than 1 is less at risk, as the ocular surface is continually protected by an intact tear film.

Clinically, in a paediatric population, I would argue speed of good data gathering whilst using the most non-invasive tools are the two most important criteria for gaining the overarching picture. Effective, clear communication directed to the patient is also very valuable, as well as using images and reports to support your explanations. The MYAH allows for rapid analysis with instructions which are simple for the patient to comprehend. These properties make the ocular surface diagnostic process very effective, particularly in children. The MYAH also provides you with a list of questions that allow you to take a comprehensive clinical history with regard to dry eye – you can choose from two dry eye questionnaires that have been validated: the DEQ-5⁹ or the Ocular Surface Disease Index (OSDI)¹⁰  dry eye questionnaire (see figure 3). The reporting tools also allow us to directly walk the patients through the data gathered in a pictorial, meaningful way.

The culmination of years of clinical experience, conferences, learning from others and utilising evidence-based research tools like the global meta-analysis reports on dry eye as well as contact lenses from TFOS and the BCLA, have helped me immensely. I feel we have better access than ever to fantastic diagnostic technology, as well as the supporting education readily available online to interpret the data acquired in a meaningful way, which allow for ever increasingly successful outcomes for patients in a complex group of ocular surface issues.