Optometrist and Head of Professional Development at Specsavers Neil Retallic sparked a discussion around the relationship between dry eye disease and depression. This article was published in the British magazine Optician.

Introduction

Philosophy means ‘love of wisdom’ and, although some debate topics such as ‘can vegetables feel pain?’ may seem peculiar, other more carefully selected choices can result in eye opening moments of deep critical thinking. For eye and health care providers thought provoking discussions, on seemingly unanswerable questions, may support with finding solutions to health service provision issues, which could ultimately enhance patient care and strengthen multidisciplinary working relationships.(1)

There are a plethora of publications linking mental health conditions, such as depression, and ocular pathology, such as dry eye disease (DED), it is therefore no surprise that this association is of interest and receiving attention (figure 1).

Figure 1: Researchers highlighting the association between mental health and dry eye from the TFOS lifestyle reports at the BCLA conference. Image courtesy of BCLA.

These complex conditions share several similarities including some common risk factors and negative impacts on quality of life and overall health. Individuals with depressive signs and symptoms (figure 2) may initially present during consultations in community eye care settings. While signs of mental health issues may not instantly jump out to the eye care practitioner during routine investigations such as dry eye assessments, with a proactive holistic approach, we are well placed to identify and support those suffering from mental health conditions and any associated ocular pathology.

Figure 2: Potential signs and symptoms of depression

Numerous studies have confirmed that depression is more prevalent in those with DED than in the general population and found links to severity levels.(2-4) One UK based study found anxiety or depression was reported by nearly half (47%) of adults with DED compared to around a third (32%) in those without the condition.(2)

These staggering statistics have provoked the question in this article’s title, between ophthalmology and psychiatry, as to how one condition may trigger the manifestation of the other.

Common risk factors

Our careful history taking can help identify key risk factors and issues that have been associated with both DED and depression, some of these include:

1. Gender, hormonal changes and age
Depression is twice as common among women than men, with the odds increasing with age.(5) Interestingly the triggers for depression also appear to be different, women more commonly present with internalising symptoms, for example around interpersonal relationships. Men most often present with externalising related symptoms, for example career and goal orientated factors.(6) Hormone-related reasons have been proposed and would also account for why depression is more common during pregnancy and the menopause.(6)

Similarly, with DED higher prevalence levels have been reported in women when compared to men and also in the menopausal and postmenopausal age groups with comorbidities. This is believed to be due to the changes in the balance of sex hormones, estrogens and androgens, which ultimately may impact the secretion of meibum, leading to DED.(7)

Neither depression nor dry eye are part of the normal ageing process, although there is evidence that some natural body changes are associated with ageing and may increase a person’s risk of experiencing depression. Recent studies suggest that lower concentrations of folate in the blood and nervous system may also contribute to depression.(8)

We know the ageing process changes numerous aspects of the ocular surface microenvironment, decreasing tear production and tear film stability, and subsequently increases the chance of DED.(9)

2. Smartphone/digital device use and lifestyle
Excessive use of digital devices has been linked to depression and dry eye. Those spending more than six hours a day viewing screens are more likely to have moderate to severe depression than those who spent less time on screens. The theory proposed is social isolation and lack of real human connections creates a vicious cycle that worsens symptoms of depression.(9) For dry eye, reducing screen exposure time and advice on blink rate and completeness may be beneficial.(10)

Vitamin A deficiency is a risk factor for dry eye(11) and nutrient deficiencies, such as vitamins D and B12, are linked to higher risks of depression.(12) Omega 3 fatty acids are associated with both conditions.(11,12) Making changes to address poor diet, and bad habits such as excessive alcohol consumption or smoking are considerations as part of management plans for patients with depression, to get their life back on track. Alcohol has been linked to tear film disturbances and dry eye disease, tobacco use to tear instability, and cocaine to decreased corneal sensitivity.(4)

3. Systemic disease and treatments
Connective tissue disorders including rheumatoid arthritis are examples of conditions that are linked to both DED and depression, as have sleep disorders.(4)

Radiation therapy and medications including those for depression have been linked to dry eye (figure 3), fuelling the debate can depression lead to dry eye and the need for an interdisciplinary approach.(13,14)

Figure 3: Ocular adverse effects for some medications used for mental health issues

Can depression or/and taking antidepressants cause dry eye?

There is support for this view and one hypothesis for why depression can lead to symptomatic dry eye is the result of a lower threshold for perceived physical pain, resulting in an increased likelihood of symptoms becoming manifest. Brain-derived neurotrophic factors may play a part, as without the ‘Miracle-Gro’ to keep the brain health functioning and to stimulate new cell growth, both depression and dry eye could result.(14)

A small-scale study found raised levels of pro-inflammatory markers (cytokines including IL-6, IL-7 and TNF) in the tear film of individuals taking antidepressants when compared to healthy controls, with the suggestion that this may lead to the worsening of DED. The larger scale Dream study concluded that inflammatory markers did not differ by depression status and found most pro-inflammatory tear marker levels were similar, except for IL-6, which were higher in antidepressant medication users.(3)

Antidepressants are powerful drugs that work by increasing the levels of neurotransmitters, such as serotonin and noradrenaline, in the brain to address chemical imbalances and improve mood. They have been shown to increase dryness in the body, including the eye. The blocking of signals between nerve cells, may lead to insufficient tear production and DED.(14) First choice medications for depression are usually selective serotonin reuptake inhibitors (SSRIs), and the most frequently prescribed are Fluoxetine (Prozac), Citalopram (Cipramil) and Sertraline (Lustral).(15) A review of antidepressant package inserts found that some (16%) document dry eye as an infrequent risk.(13) To complicate fully answering the question, although these medications may exacerbate DED, and have been identified as a risk factor for DED, effective management of depression may help to alleviate DED symptoms.(14)

Although some studies have found correlations, other studies have concluded this association to be independent of antidepressant medication use.(16) It is worth noting that studies exploring these aspects are not without limitations, given the difficulties in isolating specific parameters, further research will help us form more comprehensive conclusions.(16)

Why would dry eye diseas potentially lead to depression?

DED can reduce visual performance and impair quality of life. A potential explanation linking DED to depression is that the bur- den from the chronic ocular pain and discomfort affects the person’s ability to function effectively, triggering depression and/ or anxiety traits.(13) Studies have associated dry eye with poorer self-perceived health status and greater psychological issues. Another aspect is if the frustration of DED leads to less social interactions and feelings of unfulfilled achievements, then this could contribute to mental health issues occurring.

Co-morbidities are common among those with dry eye symptoms, with twice as many suffering from arthritis, hearing loss and irritable bowel disease as those who did not have DED. The combined impacts may impair functionality during everyday activities and predispose mental health conditions.(3)

Questionnaires: Health-related patient reported outcome measures 

For the investigation of DED, utilising the TFOS triaging questions and using questionnaires such as the OSDI and DEQ-5 are useful to complement history taking.(17)

As DED is associated with poorer health status, to assess this, the severity of disease and any impact on quality of life, researchers have established various questionnaires, that may be introduced in practice. Figure 4 gives a summary of the use and interpretation of seven useful questionnaires. The association of dry eye symptoms and depression appears better correlated than to DED signs.(4)

Figure 4: Features of questionnaires to assess disease impact

Clinical investigation of dry eye and mental health

A comprehensive routine to investigate dry eye disease is to follow the guidance in the TFOS DEWS II reports (figure 5), taking a least to most invasive test approach.(17) There are various touch points during routine consultations where signs of declined mental health can be identified, an overview is provided in figure 6. Key to success is building a good rapport with the patient, observing behaviours and responses, active listening and asking open questions with relevant follow up questions.

Figure 5: TFOS DEWS II DED Diagnosis criteria(17)

Figure 6: Touch points for considerations of wellbeing aspects(18)

Management of those with DED and depression

For the DED aspects the management plan should include the usual considerations. Typically starting with education, recommending ocular lubricants, treating any co-existing pathology, lid hygiene/warm compresses, lifestyle, environmental and dietary advice, addressing modifiable risk factors, offering in office therapies and for more advanced disease therapeutic options, punctual plugs, or other surgical approaches.(19)

For those also suffering or at risk of depression an eye care practitioner is well placed to listen, respond in an empthatic manner, provide general advice and signpost to appropriate care. Sometimes active listening and reassurance is enough. Mental Health UK advises, when having conversations about mental health, focus on how to empower the individual to set their own achievable goals to address risk factors/bad habits, establish new routines and where appropriate seek professional help rather than trying to diagnosis the condition.

Treatment for depression usually consists of self-help, medications and/or talking therapies.(20) Recent Nice guidelines for mild depression recommend behavioural therapy or group exercise should be the first line treatments instead of medication, unless this is the individual’s preference.(21) The guidance also promotes the value of other techniques such as mindfulness and meditation (figure 7).

Figure 7: Nice guidance for first line treatments for less severe depression(21)

Self-help therapies may consist of activities designed to be completed independently at times that best suits the individual. This could involve ways to introduce subtle lifestyle changes. There are also guided self-help options, for example working through a workbook or computer course with the support of a therapist.

While antidepressants can help treat the symptoms of depression, they do not always address the cause. A usual course lasts for at least six months after symptoms resolve, although for some they may be prescribed long term.(15) The benefits these drugs pro- vide, uplifting mood and behaviour, are likely to outweigh any risk of ocular manifestations such as dry eye.

About World Health Day
World Health Day is a yearly campaign in April endorsed by the World Health Organization, with the overall objective of raising awareness of mental health issues around the world and mobilising efforts in support of mental health.