Ocular implications of systemic disease

Co-management with other health care practitioners has long been a central tenet of optometric practice in Australia, with ‘Working with other practitioners’ and ‘Working within the healthcare system’ constituting two of the 10 chapters of the Code of Conduct for Optometrists (Optometry Board of Australia). The importance of these relationships is likely to increase in the future as outlined in Optometry Australia’s ‘Optometry 20/40: Key findings and priority commitments’ document, which states: ‘The future is expected to increasingly see integrated models of care, where optometry is working collaboratively (and potentially co-located) with ophthalmologists, general practitioners, the public health system and other disciplines in order to offer patients multidisciplinary, holistic health care and thereby, improve health outcomes’. This emphasis on co-management, in part, reflects the frequency with which ocular findings are related to, and need to be managed as part of a greater systemic condition. This forms the basis of this special edition of Clinical and Experimental Optometry – ‘Ocular manifestations of systemic disease’.

In contemporary practice, optometrists frequently encounter patients with ophthalmic signs and symptoms that may betray significant underlying systemic conditions. Knowledge of the characteristic ocular manifestations of systemic diseases can aid eyecare practitioners in identifying a particular disorder using clinical information acquired during a comprehensive eye examination. Alternately, patients may present with an existing health condition, and optometrists should be cognisant of the oculo-visual signs and symptoms associated with the disease and its treatment. In collaborative multidisciplinary practice, optometrists can play an important role in limiting the progression of several systemic conditions and prevent further visual loss in patients with serious ocular complications, as highlighted by a number of papers in this issue.

Endocrine disorders are among the systemic conditions that commonly present to optometry practices. In addition to diabetic eye complications, the ocular manifestations of several endocrine disorders are described in the review paper by Nowroozzadeh et al.¹ Gutteridge² focuses on one of the rheumatological diseases, ankylosing spondylitis, and its association acute anterior uveitis, and provides the major clinical considerations for optometrists in this regard.

Systemic medications as well as systemic conditions can also impact the eye. Williams and Hui³ discuss the six most prescribed class of medications in Australia and potential effects of these common drugs on the eye and visual system. Gopal et al⁴ present a case of bilateral orbital involvement in a patient with granulomatosis with polyangiitis, a rare systemic necrotising autoimmune vasculitis, in which the treatment course is complicated by steroid-induced central serous chorioretinopathy.

With about two third of Australian optometrists being therapeutically endorsed, more optometrists are now involved in glaucoma management. Considering not only the ocular side effects but also the systemic health conditions of the patients as well as the potential systemic side effects is crucial before prescribing intraocular pressure-lowering medications. Arbabi et al⁵ summarise and describe the potential systemic effects of different classes of glaucoma medication and highlight their importance in vulnerable populations, especially the elderly, pregnant, breastfeeding, and paediatric patients.

In everyday ophthalmic practice, perhaps dry eye disease is one of the most encountered and complex eye conditions, and two papers in this special issue discuss evidence that systemic conditions play a crucial role in its aetiology and presentation. Lee et al⁶ discuss the relationships between various co-morbidities and dry eye disease phenotypes which could assist in tailoring a treatment plan to the individual patient with dry eye disease in ophthalmic practice. Tavakoli and Flanagan⁷ introduce a novel take on dry eye disease, viewing it through the lens of chronic disease as a result of physiological responses of the human body to the modern environment. Our authors pay particular attention to the contributions of diet (food and beverages consumed) and nutrition to the development of dry eye disease, and its interplay with the gut microbiome.⁷ While considerably more research needs to be done in this field, this review provides much needed guidance for practitioners managing patients with dry eye disease.

Given the timing of this issue, implications of COVID-19 for clinical optometry are also considered. Since the beginning of the COVID-19 global pandemic several strategies including personal protective equipment has been implemented to stop infection transmission. Kalaiselvan et al⁸ confirm the effectiveness of face masks in reducing the transmission of microbes which has applications in optometric care. They highlight the importance of frequent replacement of the masks, or appropriate washing in case of reusable types, in order to reduce the contamination.⁸

In many ways, the eye, particularly the retina, can be considered as part of the brain. It is the only part of the brain that can be seen directly and non-invasively and the two organs share common disease mechanisms, including vascular abnormalities, inflammation, mitochondrial dysfunction, aggregation of misfolded proteins and changes in fluid dynamics.⁹ As such, it is unsurprising that neurological conditions are evident through examination of the retina and assessment of vision as highlighted by a number of papers in this edition.

Given its association with acute and transient vision loss, optometrists have long played an important role in the diagnosis and management of stroke. Kalloniatis et al¹⁰ review the vascular supply of the brain and the ocular signs and symptoms of stroke and retinal ischaemia. They also include a recommended workflow for examination and management of suspected ischaemic events for clinical practice.

Delmadoros¹¹ highlights a much less common neurological condition, describing a case of previously misdiagnosed craniopharyngioma, where an optometrist was instrumental in the detection, and prompt referral to a neuro-ophthalmologist. This report also includes a review of the ocular manifestations of craniopharyngioma.

This edition of Clinical and Experimental Optometry highlights the relationship between the eye and the body. This relationship is two-sided. Unfortunately, given the complex nature and intricacies of ocular structures and tissues, they are susceptible to damage from many systemic conditions and medications, causing discomfort and threatening vision, as evidenced by the many cases and evidence in this edition described above. However, the unique properties of the eye, being readily directly imaged, allows us to see the onset and monitor these same diseases, which is not possible elsewhere in the body. This provides great opportunities to understand the pathophysiology of disease, as well as developing new diagnostic tests, and better monitor treatments. This has obvious advantages for clinical care of patients, but also provides a potential new role for optometry in the management of systemic diseases.

Given the impact that systemic disease can have on the tear film and ocular surface, and the ease of collection of the tear film, it comes as no surprise that increasingly researchers are turning to the tear film for biomarkers that might aid in the diagnosis and management of the disease. Alotaibi and colleagues¹² review the evidence for tear-borne molecular biomarkers for a range of chronic, non-infectious disease such as diabetes mellitus, multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, migraine, systemic sclerosis, cystic fibrosis, and cancer. The authors highlight the advantages of using the tear film in this context, but also identify the current challenges of assaying small volumes, and the need to improve analytical sensitivity.¹²

As with the tear film, retinal imaging is increasingly being explored for biomarkers of neurodegenerative diseases including Alzheimer’s disease, Parkinson’s disease, Lewy body dementia, frontotemporal dementia, Huntington’s disease and multiple sclerosis. The embryological similarities in vascular and neuronal anatomy of the retina and the forebrain during development, and the access to instruments such as optical coherence tomography, with or without angiography, have enabled the retina to be used to gain insight into brain structure and function. Christinaki et al¹³ prepare eyecare providers for their future role as diagnosticians in this area by providing an overview of the current status of retinal imaging biomarkers. McKendrick and Nguyen¹⁴ focus on the role of retinal imaging in patients with migraine, and the potential for current technology to inform the practitioner of microstructural damage and vascular dysregulation in the eyes of people with migraine.

Reflecting upon of the cases and evidence discussed in this issue, co-management represents an important part of contemporary optometry today in Australia and New Zealand. This role will continue to grow and become even more important in the future. As the eyecare landscape changes and technology improves, we are likely to find our role transitioning from retail focused to the provision of a more multidisciplinary, holistic model of care, with co-management and even co-location with other health care providers, such as general practitioners and ophthalmologists. This will necessitate clinicians becoming even more familiar with identifying and managing ocular manifestations of systemic disease. As outlined in this special edition, it may also provide an exciting opportunity for optometrists to play a wider role as diagnosticians in a wide range of systemic diseases. As the evolving roles and increasing responsibilities of optometrists in Australia and New Zealand over the past few decades has shown, optometry as a profession is dynamic, adaptable, and capable of meeting this potential.