A Study on Frequency of Visual Field Testing in Glaucoma
A Study on Frequency of Visual Field Testing in Glaucoma
Aim To estimate current clinical practice for frequency of visual field (VF) monitoring in glaucoma in England.
Methods A cross-sectional review of all patients with chronic open angle glaucoma (COAG) attending specialist glaucoma clinics at six hospitals in England was performed. The number of VF tests undertaken prior to the study date and during the first 2 years since diagnosis were recorded and compared with European Glaucoma Society (EGS) guidelines for newly-diagnosed patients. Clinician-requested monitoring intervals were compared with intervals from the National Institute of Clinical Excellence (NICE) guidelines, and the relationships with disease severity, intraocular pressure (IOP) and glaucoma progression status were reviewed.
Results One-hundred and four patients with COAG were included. 73 patients had at least 2 years of follow-up. Median (IQR) total number of VF tests and in the first 2 years of diagnosis were 4 (2–7) and 2 (2–3), respectively. No patients met EGS guidelines, but 87% of patients had their monitoring intervals requested in accordance with NICE guidelines. These intervals were not related to disease severity or VF stability (Kruskal–Wallis test, p=0.25) but shortened significantly when IOP control was inadequate or when the overall clinical impression was disease progression (p<0.001).
Conclusions Most newly-diagnosed COAG patients receive less than three VFs in the first 2 years following diagnosis and an average of 0.7 VF per year over the duration of follow-up.
Patients with chronic open angle glaucoma (COAG) represent a major workload of hospital eye services. The guidelines for glaucoma published by the National Institute of Clinical Excellence (NICE) in the UK highlighted the lack of evidence about how patients with the condition should be monitored over time. The NICE Guideline Development Group made a few important recommendations for essential future research, including the urgent need to establish the clinical-effectiveness and cost-effectiveness of using different monitoring strategy in patients diagnosed with glaucoma.
The aim of glaucoma management is to reduce or halt visual loss and preserve the patient's quality of life. Monitoring patients' visual field (VF) to detect functional progression should be a key element of that clinical management. Ideally, any VF progression should be ameliorated to a rate which is compatible with a sighted lifetime without significant disability. Rates of VF progression often vary widely between patients and timely detection of progression requires accurate and consistent measurements of VFs over a period of years. The European Glaucoma Society (EGS) recommends that all newly-diagnosed glaucoma patients should be tested three times per year during the first 2 years in order to establish the rate of VF loss at an early stage. These 'ideal' monitoring intervals are supported by results from studies using statistical modelling, computer simulation or retrospective assessment of large VF databases. In particular, Chauhan and colleagues published practical recommendations for measuring rates of VF change in glaucoma patients based on empirical data and statistical modelling; they concluded that three examinations per year are required to identify an overall change in mean deviation (MD) of 4 dB over 2 years in a patient with average VF variability.
There is a strong rationale for frequent monitoring to detect the rapidly progressing patient because, from a healthcare planning perspective, the cost of glaucoma management increases considerably with the severity of visual loss. Meanwhile, with a significant number of patients having stable treated disease, there are potential cost implications by performing a greater number of tests than are necessary. With the current incidence of COAG estimated to be approximately 9000 new cases per year (excluding glaucoma suspects or those with ocular hypertension), valuable resources could be redistributed by optimising the monitoring guidelines to maintain disease stability; however, this could be offset by reduced statistical sensitivity to detect VF progression, which may in turn lead to disease worsening and treatment escalation. This fine balance is further complicated by what is achievable with the resources currently available.
The aim of this multi-centre cross-sectional study was first to ascertain the current practice of VF testing for monitoring patients with glaucoma in England and, second, to evaluate this practice in relation to EGS and NICE guidelines. The results are valuable for healthcare providers and represent an important starting point for research on optimising VF testing in newly-diagnosed patients.
Abstract and Introduction
Abstract
Aim To estimate current clinical practice for frequency of visual field (VF) monitoring in glaucoma in England.
Methods A cross-sectional review of all patients with chronic open angle glaucoma (COAG) attending specialist glaucoma clinics at six hospitals in England was performed. The number of VF tests undertaken prior to the study date and during the first 2 years since diagnosis were recorded and compared with European Glaucoma Society (EGS) guidelines for newly-diagnosed patients. Clinician-requested monitoring intervals were compared with intervals from the National Institute of Clinical Excellence (NICE) guidelines, and the relationships with disease severity, intraocular pressure (IOP) and glaucoma progression status were reviewed.
Results One-hundred and four patients with COAG were included. 73 patients had at least 2 years of follow-up. Median (IQR) total number of VF tests and in the first 2 years of diagnosis were 4 (2–7) and 2 (2–3), respectively. No patients met EGS guidelines, but 87% of patients had their monitoring intervals requested in accordance with NICE guidelines. These intervals were not related to disease severity or VF stability (Kruskal–Wallis test, p=0.25) but shortened significantly when IOP control was inadequate or when the overall clinical impression was disease progression (p<0.001).
Conclusions Most newly-diagnosed COAG patients receive less than three VFs in the first 2 years following diagnosis and an average of 0.7 VF per year over the duration of follow-up.
Introduction
Patients with chronic open angle glaucoma (COAG) represent a major workload of hospital eye services. The guidelines for glaucoma published by the National Institute of Clinical Excellence (NICE) in the UK highlighted the lack of evidence about how patients with the condition should be monitored over time. The NICE Guideline Development Group made a few important recommendations for essential future research, including the urgent need to establish the clinical-effectiveness and cost-effectiveness of using different monitoring strategy in patients diagnosed with glaucoma.
The aim of glaucoma management is to reduce or halt visual loss and preserve the patient's quality of life. Monitoring patients' visual field (VF) to detect functional progression should be a key element of that clinical management. Ideally, any VF progression should be ameliorated to a rate which is compatible with a sighted lifetime without significant disability. Rates of VF progression often vary widely between patients and timely detection of progression requires accurate and consistent measurements of VFs over a period of years. The European Glaucoma Society (EGS) recommends that all newly-diagnosed glaucoma patients should be tested three times per year during the first 2 years in order to establish the rate of VF loss at an early stage. These 'ideal' monitoring intervals are supported by results from studies using statistical modelling, computer simulation or retrospective assessment of large VF databases. In particular, Chauhan and colleagues published practical recommendations for measuring rates of VF change in glaucoma patients based on empirical data and statistical modelling; they concluded that three examinations per year are required to identify an overall change in mean deviation (MD) of 4 dB over 2 years in a patient with average VF variability.
There is a strong rationale for frequent monitoring to detect the rapidly progressing patient because, from a healthcare planning perspective, the cost of glaucoma management increases considerably with the severity of visual loss. Meanwhile, with a significant number of patients having stable treated disease, there are potential cost implications by performing a greater number of tests than are necessary. With the current incidence of COAG estimated to be approximately 9000 new cases per year (excluding glaucoma suspects or those with ocular hypertension), valuable resources could be redistributed by optimising the monitoring guidelines to maintain disease stability; however, this could be offset by reduced statistical sensitivity to detect VF progression, which may in turn lead to disease worsening and treatment escalation. This fine balance is further complicated by what is achievable with the resources currently available.
The aim of this multi-centre cross-sectional study was first to ascertain the current practice of VF testing for monitoring patients with glaucoma in England and, second, to evaluate this practice in relation to EGS and NICE guidelines. The results are valuable for healthcare providers and represent an important starting point for research on optimising VF testing in newly-diagnosed patients.
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