At the completion of this CPD activity, optometrists will have developed their knowledge of glaucoma management. Including:
- Understand the structural and functional indices that play a role in the monitoring of glaucoma
- Inform their own glaucoma-management plan based on assessment techniques and workflow used at the CFEH’s Glaucoma Management Clinic
- Recognise some uncommon differential diagnoses for patients presenting with glaucoma-like clinical features
- Review an example of a collaborative approach to the diagnosis and management of a patient presenting with potentially glaucomatous clinical features
NOTE: Optomery Australia members can enter their details at the bottom of this article to have it automatically added to their Learning Plan.
When the Centre for Eye Health established its Glaucoma Management Clinic eight years ago, it wanted to provide a new care model that would be more efficient for clinicians and easier to navigate for patients. DR JACK PHU and HENRIETTA WANG share key learnings from the clinic.
Dr Jack Phu
BOptom (Hons), BSc, MPH, PhD, FAAO, Diplomate (Glaucoma)
Lecturer, School of Optometry and Vision Science, UNSW
Henrietta Wang
BOptom (Hons), BSc, FAAO
Senior Staff Optometrist/Research Optometrist, Centre for Eye Health, UNSW
Glaucoma is a chronic, progressive disease that requires lifelong management to prevent irreversible blindness.1 With an ageing population, the burden of the disease is expected to increase, presenting a challenge to the limited resources available in the healthcare system.
In particular, ophthalmologists and the public health system are expected to be overburdened by an increasing volume of patients with or suspected of having glaucoma.2 To alleviate this burden, an alternative pathway is required that can manage the allocation of precious healthcare resources to where they are most needed.
In March 2022, the Centre for Eye Health (CFEH) at the University of New South Wales marked the eighth year of operation of its Glaucoma Management Clinic (GMC). Staffed by optometrists and technicians from the CFEH and consulting ophthalmologists from the Prince of Wales Hospital, the GMC was designed to reduce the burden of glaucoma on the public hospital healthcare system by providing an alternative, no-cost pathway for patients suitable for collaborative care.3
The collaborative care model follows the best practice and collaborative care guidelines established at the time, including guidelines from the Optometry Board of Australia, the Royal Australian and New Zealand College of Ophthalmologists (RANZCO), and the National Health and Medical Research Council (NHMRC). Patients are suitable for collaborative care if they met specific thresholds, such as early-to-moderate stages of glaucoma, stability while on medical therapy and uncomplicated by other significant ocular comorbidities.4 Patients who did not meet the criteria for collaborative care were referred onward to the ophthalmology department of their local health district.
After eight years of working alongside ophthalmologists from the local health district in this collaborative setting, we would like to share some of our experiences and key learning points with the readers of Insight. Our hope is that more collaborative arrangements in the community can emerge to tackle the significant public health issue of glaucoma diagnosis and management.
Pathways to collaborative care
A patient can enter the GMC through three main pathways.3
Pathway 1: Accessible care (direct community referral)
The first pathway is a direct referral from a community clinician, typically an optometrist. Such a patient would have a history of diagnosed glaucoma that meets the criteria for collaborative care, or are highly suspicious for developing glaucoma. Such patients might already be on treatment. Typically, the patients have financial constraints and are unable to afford ongoing care in a private setting.
Pathway 2: Referral refinement (internal referral from the CFEH General Clinic)5
The second pathway is an internal referral of an existing patient seen in the General Clinic of the CFEH. The General Clinic is where most referrals to CFEH are sent. These would typically include patients with risk factors for glaucoma who require further comprehensive assessment. Patients who are initially seen in the General Clinic might eventually develop signs of glaucoma, and are given the option to be seen in the GMC for treatment initiation and follow up.
Pathway 3: Direct referral from the Prince of Wales Hospital
As one of the goals of the GMC is to reduce the burden of glaucoma in the public healthcare system, we will often take over care of patients sent to our clinic directly from the Prince of Wales Hospital. These are often patients who are glaucoma suspect or have glaucoma that has demonstrated long-term stability. Such patients are excellent candidates for our collaborative care setting and free-up hospital appointment times for more in-need patients.
Practice point 1: Identify the most suitable level of glaucoma care required for each patient, and identify the pathway that enables them to best access that level of care.
How might these pathways be applied in community care or private practice? – A commonality among these pathways is the process of having experts review patients and their individual glaucoma care needs. The fundamental question is which level of eyecare – primary, intermediate, tertiary – does the patient require and what is the best way for the patient to access that level of care?
The CFEH model is able to leverage expertise from highly-experienced, recognised experts in glaucoma who are able to provide second opinions on cases.6 These act as another opportunity to increase case detection rates (true positives) and reduce false-positive referrals.5 Many of these refinement steps can be done asynchronously, (for example: remote review of electronic medical records including visual field and imaging results). A similar approach can be done in private practice. Given the availability of technology such as visual field testing and optical coherence tomography, it is simple enough to ask a colleague or collaborator (optometrist or ophthalmologist) for an opinion.
In the sections below, we will be detailing our experiences on establishing effective communication channels and pathways that facilitate the most appropriate collaborative care plans.
What does a glaucoma-specific clinical examination look like? – Optometry Australia has recently released a document outlining current, evidence-based recommendations for clinical examination techniques for glaucoma.7 Many of the techniques remain similar to the older NHMRC guidelines for glaucoma,8 with several more recent paradigms being recognised for their importance. The indispensable nature of ocular imaging (colour fundus photography and optical coherence tomography), intraocular pressure profiling and the importance of high volumes of perimetric testing have been emphasised.9
Figure 1 (below or clearer version accessible here) provides a list of assessment techniques and workflow for a glaucoma assessment performed at CFEH, including instances where further investigations are required.
Our clinical thought processes at the CFEH focus on two main questions for patients seen in the GMC.9 First, are the patient’s ocular findings consistent with glaucoma, or are they explained by an alternative diagnosis? Second, if the patient has glaucoma, what is the trajectory of the disease and how should we arrest it?
Glaucoma is a diagnosis of exclusion – It is often tempting to diagnose glaucoma in patients who have significant retinal nerve fibre layer thinning (RNFL) and visual field loss. Although glaucoma is the most commonly diagnosed optic neuropathy, it is also a diagnosis of exclusion. Recent studies have suggested that up to half of patients diagnosed with glaucoma do not have the disease (in other words: a false positive diagnosis).10
Before we commit a patient to a lifetime of treatment and follow up, we must be certain that the diagnosis is correct. Aside from other common optic nerve diseases such as optic nerve head drusen or optic neuritis, considerations for alternative diagnoses and the workflow are listed in Table 1.
The GMC shows how an additional layer of clinical care can differentially diagnose glaucoma. Processes should be in place, such as additional supplementary testing (including increased volumes of visual field testing and intraocular pressure profiling) that aim to reduce false positive glaucoma diagnoses. As part of the differential diagnosis process, further tests include blood panels (for systemic inflammation), carotid doppler ultrasound (for carotid stenosis), and neuroimaging (for lesions of the visual pathway beyond the retina).
Practice point 2: Clinical assessment of glaucoma needs to be comprehensive to accurately differentially diagnose glaucoma from other retinal, optic nerve or visual pathway pathologies and manage expected disease trajectory.
What is the trajectory of glaucoma? – The goal of glaucoma management is to prevent irreversible visual impairment within a patient’s lifetime. As part of that process, clinicians need to carefully assess the risk of progression, project the likely visual outcome over time and titrate treatment appropriately.
Both structural and functional indices play a role in the monitoring of glaucoma. Static automated perimetry, the current clinical standard for monitoring visual function across the visual field, remains critical for assessing the risk of functional impairment. Perimetry results are correlated with activities of daily living and quality of life, are patient-relevant indicators for treatment success.
Disease trajectory is assessed by either pointwise or global analysis of perimetry results. For example, pointwise examination of the location of visual field loss (central or peripheral) reveal areas pertinent to a patient’s visual function. Assessing mean deviation worsening (global analysis) provides a quantitative overview of disease progression rate over time. Potentially useful indicators include the mean deviation levels at worsening stages of glaucoma (worse than -6 dB for moderate glaucoma, worse than -12 dB for advanced glaucoma, and worse than -22 dB for severe glaucoma).11
Practice point 3: Ongoing development of clinical knowledge is essential for evidence-based assessment and management, and this should be supplemented by legible and interpretable clinical data presentation.
Continuing education is essential – In the eight years since the start of the GMC, a notable change that we’ve observed in our clinic is the increase in the confidence and initiative of staff optometrists. Developing the required confidence involves time and work.
At the CFEH, we are fortunate to have the capacity to develop expertise and leadership in the field of glaucoma and optic nerve disease through our research and education programs. This has translated into improving the capacity of clinical staff through the dissemination of the latest in evidence-based medicine in glaucoma.9 Two major innovations implemented in our clinic have been frontloading visual field tests for earlier detection of glaucomatous change,12,13 and the deployment of intraocular pressure profiling including iCare HOME self-tonometry.14
It is challenging to remain informed of the latest in evidence-based practice in any field. There are many resources available to optometrists, including continuing education programs, podcasts, research papers and quality-assured CPD articles like the one you are currently reading.
Quality in collaboration – In addition to the underlying knowledge of the patient’s case and the clinical evaluation process, it’s also essential to prepare clinical data in a form that is legible, interpretable and unambiguous to other members of the healthcare team. A practice management system that allows collation of all relevant clinical data provides a convenient platform for visualisation. The FORUM software from Carl Zeiss Meditec is an example of a platform that can integrate visual field, optical coherence tomography data and colour fundus photographs.
Case study
Knowledge and application of evidence-based medicine provides structure to case analysis and a systematic approach to diagnosis and management. Here we describe a case that we recently assessed and managed in the GMC.
First visit
A 63-year-old female was referred to the CFEH GMC by her optometrist who noted ‘large cupping’ in both eyes. She denied any visual or ocular symptoms. Her best-corrected visual acuities were 6/6-2 in the right eye and 6/6– in the left eye. While her personal ocular history was unremarkable, she had a distant family history of glaucoma (grandfather). Her self-reported medical history was also unremarkable. Her entrance test findings are summarised in Table 2.
Dilated fundus examination showed average-sized discs with wide but shallow cups in both eyes. The neuroretinal appeared intact in the right eye and slightly thin superotemporally in the left eye with corresponding loss of RNFL reflectivity (Figure 2A-B).
The temporal aspect of the neuroretinal rim appeared pale in the left eye. There were no disc haemorrhages present. Optical coherence tomography (OCT) results were concordant with funduscopic findings and showed superotemporal RNFL and ganglion cell-inner plexiform layer (GC-IPL) thinning in the left eye (Figure 2C-D). Visual field testing (24-2 test grid) showed a clear right field and an inferonasal defect in the left eye (Figure 2E-F).
While there were some features typical for glaucoma present (cupping, RNFL and GC-IPL thinning with a corresponding field defect), the depth of neuroretinal rim thinning was disproportionate to the extent of RNFL/GC-IPL loss. The presence of pallor was also atypical for glaucoma. As the clinical picture was suspicious but not conclusive for glaucoma, the patient was booked in for glaucoma supplementary testing at CFEH.
Second visit
The patient returned four months later. Her ocular and medical histories were unchanged. Repeat visual field testing was performed and confirmed the inferonasal defect in the left eye with no evidence of progression from the last visit. A water-drinking test was also undertaken to assess the patient’s intraocular pressure response to osmotic stress. Her water drinking test results are shown in Table 3.
No significant elevation in intraocular pressure was noted. OCT-Angiography of the optic nerve was also performed and showed reduced capillary perfusion in the superotemporal peripapillary regions, corresponding to the areas of RNFL thinning (Figure 3).
Considering the functional stability and the less than 4 mmHg spike in intraocular pressure associated with the water-drinking test, non-glaucomatous conditions needed to be excluded. Thus, the patient was referred for neuroimaging of the head and orbit.
Third visit
Three months later, the patient returned to review her neuroimaging results with our consulting ophthalmologist. Magnetic resonance imaging with contrast showed background moderate chronic microvascular ischaemic change. These findings were suggestive of an ischaemic optic neuropathy rather than glaucoma. The patient was advised to see her general practitioner for evaluation of her cardiovascular disease risk factors. She was also scheduled for a six-month review at the CFEH.
This case demonstrates the value of a collaborative approach to diagnosis and management of patients with clinical features highly suspicious for glaucoma.
Conclusions
Glaucoma is a common cause of irreversible vision loss in the community, and represents a significant burden to the healthcare system. Clinicians need to be judicious in managing patients with glaucoma, keeping in mind outcomes that are relevant to the patient, including their quality of life and impact on activities of daily living. There are strategies in place that are effective in reallocating precious resources to those in need. Optometrists play a vital role in the journey of care of patients with glaucoma.
References
1. Tham YC, Li X, Wong TY, et al. Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmology 2014; 121 (11): 2081-90.
2. Phu J, Masselos K, Sullivan-Mee M, Kalloniatis M. Glaucoma Suspects: The Impact of Risk Factor-Driven Review Periods on Clinical Load, Diagnoses, and Healthcare Costs. Transl Vis Sci Technol 2022; 11 (1): 37.
3. Huang J, Hennessy MP, Kalloniatis M, Zangerl B. Implementing collaborative care for glaucoma patients and suspects in Australia. Clin Exp Ophthalmol 2018; 46 (7): 826-8.
4. White A, Goldberg I, Australian, et al. Guidelines for the collaborative care of glaucoma patients and suspects by ophthalmologists and optometrists in Australia. Clin Exp Ophthalmol 2014; 42 (2): 107-17.
5. Huang J, Yapp M, Hennessy MP, et al. Impact of referral refinement on management of glaucoma suspects in Australia. Clin Exp Optom 2020; 103 (5): 675-83.
6. Jamous KF, Kalloniatis M, Hennessy MP, et al. Clinical model assisting with the collaborative care of glaucoma patients and suspects. Clin Exp Ophthalmol 2015; 43 (4): 308-19.
7. Clinical Practice Guide for the Diagnosis and Management of Open Angle Glaucoma. Optometry Australia, 2020.
8. National Health and Medical Research Council. Guidelines for the screening, prognosis, diagnosis, management and prevention of glaucoma. Internet: Commonwealth of Australia, 2010.
9. Phu J, Agar A, Wang H, et al. Management of open-angle glaucoma by primary eye-care practitioners: toward a personalised medicine approach. Clin Exp Optom 2021; 104 (3): 367-84.
10. Founti P, Coleman AL, Wilson MR, et al. Overdiagnosis of open-angle glaucoma in the general population: the Thessaloniki Eye Study. Acta Ophthalmol 2018; 96 (7): e859-e64.
11. Mills RP, Budenz DL, Lee PP, et al. Categorizing the stage of glaucoma from pre-diagnosis to end-stage disease. Am J Ophthalmol 2006;141(1):24-30.
12. Phu J, & Kalloniatis M. Viability of Performing Multiple 24-2 Visual Field Examinations at the Same Clinical Visit: The Frontloading Fields Study (FFS). Am J Ophthalmol, 2021;230, 48-59.
13. Phu J, & Kalloniatis M. The frontloading fields study (FFS): Detecting changes in mean deviation in glaucoma using multiple visual field tests per clinical visit. Transl Vis Sci Technol, 2021; 10 (13).
14. Phu J, Masselos K, & Kalloniatis M. Deployment of the Water Drinking Test and iCare HOME Phasing for Intraocular Pressure Profiling in Glaucoma Evaluation. Optom Vis Sci, 2021; 98 (11), 1321-1331.
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