Chronic Dry Eye Disease (DED) presents a challenge for optometrists and ophthalmologists, with the nature of chronic disease in general being difficult to understand and treat. Chronic DED often leads to significant psychological distress, increasing subjective pain. Sometimes the pain of DED is non-ocular, as the patient has become more neurologically sensitive to pain. Optometrists and ophthalmologists should also be aware of some commonly missed or under-diagnosed conditions that can contribute to chronic DED.
Mild or acute cases of dry eye associated with conditions like meibomian gland dysfunction (MGD), anterior blepharitis, or bouts of increased screen time, are often easily improved with artificial tears, heat-based treatments, lid hygiene and behavioural modifications.
we need to be aware of signs of depression and anxiety and not be afraid of referring to a GP for further professional help
The vast majority of patients that present to our dedicated Dry Eye Clinic in the Sydney central business district are unfortunately past the point of a (relatively) quick fix, complaining of long standing symptoms that have existed for months to years, with little to no improvement, or worsening over time.
This patient cohort presents quite a challenge for a variety of reasons. Chronic pain is often much more difficult to describe compared to acute pain. Listening to, and acknowledging, someone’s chronic pain is powerful, even if a clear-cut treatment plan doesn’t exist.
These patients often flit from practitioner to practitioner in search of relief. It is important to explain that following a particular treatment methodology, rather than chopping and changing, is more likely to yield a better outcome. Long term problems require long term solutions, and there are no quick fixes or cures.
The emotional distress of chronic dry eye often outweighs – and in fact exacerbates – physical symptoms and signs. When one of my patients confessed that she felt like having her eyes removed, rather than continue dealing with her chronic dry eye disease, I knew she was in a significant amount of pain and psychological distress. This patient had only trace amounts of corneal punctate epithelial erosions, and mild to moderate MGD; however, her eyes would sometimes feel so dry by the end of the day that it prevented her from going out and socialising in the evenings. She felt as though many of her important relationships with others were being adversely affected because of her eyes.
Dry eye often leads to behavioural and lifestyle changes, which can result in feelings of social dissatisfaction and isolation. Depressive states can then lead to a general lack of motivation – lack of motivation to lead a healthy lifestyle (poor diet, poor sleep,1 staying indoors) and lack of motivation to consistently follow treatment regimens. This can create and continually feed into a vicious cycle of DED.
Recent studies have found that patients experiencing dry eye symptoms had higher depression and anxiety scores,1 with increasing severity of symptoms associated with worse scores on psychological wellbeing questionnaires.2 Higher amounts of psychological stress were also associated with a higher risk of dry eye.3
As clinicians, we need to be aware of signs of depression and anxiety and not be afraid of referring to a GP for further professional help. Simple questions, such as the Whooley Questions,4 can help identify whether or not a patient could benefit from further evaluation for depression.
ASSESSING TREATMENT EFFICACY AND MANAGING EXPECTATIONS
In addition to signs of DED on slit-lamp examination, symptom and pain scores should be assessed and recorded. Chronic pain symptoms are often more difficult to describe than acute pain symptoms. Anatomical diagrams can provide a useful adjunct to standard questionnaires such as the Ocular Surface Disease Index (OSDI). Providing a detailed diagram of the face and eyes, for example, can help patients more accurately locate and describe their pain, as can a numbered pain scale.
Establishing these baselines helps with initial diagnosis and provides a baseline for assessing treatment efficacy. Perhaps more powerfully, the act of self-assessment on a pain scale can improve a patient’s attitude toward their pain. Patient’s with longstanding symptoms can often over-estimate or exaggerate the amount of pain they are experiencing. On a pain scale, ‘severe’ pain means being unable to get out of bed or perform basic tasks – a patient that is capable of coming in to an optometry clinic does not generally fall into this category.
Patients that achieve very slow improvements to their condition over time will often report they have had no improvement in their symptoms. At follow-up examinations, reassessment of symptom and pain scores and comparing them to initial results often determines whether or not this is true. Highlighting any improvement to scores at follow-up visits helps boost morale and encourages adherence to treatment regimes.
Similarly, a patient can easily miss a slow deterioration of their DED over weeks and months if they stop adhering to their treatment protocol. Pointing out changes in their scores over time can help them get back on track. Chronic pain and depression can also lead to a lack of motivation in completing goal-directed tasks,5 which clearly spells trouble for treatment regimens involving things like long term daily lid hygiene.
We often come across patients with minimal clinical signs of dry eye, yet they report very severe dry eye pain. It may be worth asking these patients whether or not they experience other types of pain, such as irritable bowel syndrome (IBS), chronic pelvic pain or fibromyalgia – as other chronic pain syndromes have been associated with DED and may share underlying genetic mechanisms.6 It has been postulated that this could be due to centralised neuronal sensitisation and a lack of pain-lowering modulation, causing widespread hypersensitivity to pain.7
Patients with DED who also suffer from a chronic pain syndrome, score significantly higher on 10 out of 12 questions on the OSDI, yet they have significantly less corneal staining and better Schirmer results than dry eye patients without chronic pain.8 Animal studies have demonstrated that corneal nerves can become hypersensitive following inflammation,9 and some studies have shown that patients with DED have a reduced sub-basal corneal nerve density on confocal microscopy – although other studies refute this by demonstrating an increase, or no change.10
There are no standardised tests for determining whether a patient’s dry eye symptoms are due to neuropathic pain; however suspicion should be raised when symptoms far exceed signs, there is little or inadequate response to treatments that improve the tear film, there are coexisting chronic pain conditions, a history of corneal surgery, depression and/or anxiety, spontaneous burning or light sensitivity, or persistent pain following topical corneal anaesthesia.10
Clearly this cohort is one of the most challenging to treat, especially when they exhibit only minimal signs of dry eye on their ocular surface. Increased lubrication should reduce environmental triggers that can exacerbate nerve pain, so treatments like preservative free artificial tears and MGD therapy should still be considered. Omega-3 supplementation has been studied for non-ocular pain as well as MGD, and may act to mediate neuro-active effects in peripheral nerve injury.11 Supplementation may thus improve symptoms due to a reduction in nerve hypersensitivity, rather than improving the ocular surface itself.
Non-ocular pain treatments can include autologous serum12 and amniotic membranes,13 which aim to regenerate corneal nerves. Botox injections for migraine sufferers have also been shown to improve concomitant dry eye symptoms, possibly due to modulation of shared trigeminal nerve pathways.14 Other pain management therapies, such as oral pain and anti-depressant medication, may also be required in these individuals.
AM I MISSING SOMETHING?
Anecdotally, certain conditions that contribute to DED are often missed, under-diagnosed or under-treated. Some of these are described in the table (right).
Chronic DED presents a challenging disease entity for eye health providers. Establishing baselines by using symptom questionnaires, diagrams, and pain scales is a handy metric to assess treatment efficacy and overall subjective response. Acknowledging a patient’s distress and the significance that DED has had on their lives is powerful, and can facilitate a discussion regarding referral for psychological evaluation if required. Conditions such as nocturnal lagophthalmos, ocular rosacea and SLK are often missed and should always be ruled out during any dry eye examination.
Dr Alex Koutsokeras is a therapeutically endorsed clinical optometrist with particular expertise in specialty contact lenses and dry eye management. She achieved her Optometry degree with first class honours from the University of Auckland. Prior to this, she completed a Psychology degree from the University of Sydney. Dr Koutsokeras has also completed advanced studies in glaucoma.
- Wu M, Liu X, Han J, Shao T, Wang Y. Association Between Sleep Quality, Mood Status, and Ocular Surface Characteristics in Patients With Dry Eye Disease. Cornea. 2019;38(3):311-7.
- Singh L, Singh VP, Yadav S, Garg P. Mental Health Status in Dry Eye Disease–a Case Control Study. Journal-Mental Health Status in Dry Eye Disease–a Case Control Study.
- Hyon JY, Yang HK, Han SB. Dry Eye Symptoms May Have Association With Psychological Stress in Medical Students. Eye & contact lens. 2019;45(5):310-4.
- Whooley Questions for depression screening [Internet]. . Available from: https://whooleyquestions.ucsf.edu/.
- Schwartz N, Temkin P, Jurado S, Lim BK, Heifets BD, Polepalli JS, et al. Decreased motivation during chronic pain requires long-term depression in the nucleus accumbens. Science. 2014;345(6196):535-42.
- Vehof J, Zavos HM, Lachance G, Hammond CJ, Williams FM. Shared genetic factors underlie chronic pain syndromes. PAIN®. 2014;155(8):1562-8.
- Kindler LL, Bennett RM, Jones KD. Central sensitivity syndromes: mounting pathophysiologic evidence to link fibromyalgia with other common chronic pain disorders. Pain management nursing. 2011;12(1):15-24.
- Vehof J, Smitt-Kamminga NS, Kozareva D, Nibourg SA, Hammond CJ. Clinical characteristics of dry eye patients with chronic pain syndromes. Am J Ophthalmol. 2016;162:5,65. e2.
- Belmonte C, Acosta MC, Gallar J. Neural basis of sensation in intact and injured corneas. Exp Eye Res. 2004;78(3):513-25.
- Galor A. Painful Dry Eye Symptoms: A Nerve Problem or a Tear Problem? Ophthalmology. 2019;126(5):648-51.
- Galan-Arriero I, Serrano-Munoz D, Gomez- Soriano J, Goicoechea C, Taylor J, Velasco A, et al. The role of Omega-3 and Omega-9 fatty acids for the treatment of neuropathic pain after neurotrauma. Biochimica et Biophysica Acta (BBA)-Biomembranes. 2017;1859(9):1629-35.
- Aggarwal S, Kheirkhah A, Cavalcanti BM, Cruzat A, Colon C, Brown E, et al. Autologous serum tears for treatment of photoallodynia in patients with corneal neuropathy: efficacy and evaluation with in vivo confocal microscopy. The ocular surface. 2015;13(3):250-62.
- Morkin MI, Hamrah P. Efficacy of self-retained cryopreserved amniotic membrane for treatment of neuropathic corneal pain. The ocular surface. 2018;16(1):132-8.
- Diel RJ, Hwang J, Kroeger ZA, Levitt RC, Sarantopoulos CD, Sered H, et al. Photophobia and sensations of dryness in patients with migraine occur independent of baseline tear volume and improve following botulinum toxin A injections. Br J Ophthalmol. 2019;103(8):1024-9.