Dr Roshini Sanders summarises the recent SIGN guideline on glaucoma referral and safe discharge, and explains how early diagnosis can improve patient outcomes

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Read this article to learn more about:

  • the importance of an early diagnosis
  • the three tests used for diagnosing glaucoma and examination techniques used in primary care
  • criteria for patient referral to hospital eye services.

Key points

GP commissioning messages

Glaucoma is a disease characterised by visual impairment as a consequence of reduced blood supply to the optic nerve head. The most common form of the disease is chronic open angle glaucoma whereby aqueous fluid fails to drain through the trabecular meshwork, leading to raised intraocular pressure, which compromises blood flow to the optic nerve head. This leads to loss of optic nerve fibres and clinically manifests itself by patients experiencing visual field loss sometimes in combination with reduced visual acuity.1 It is a global problem and one of the leading causes of preventable blindness.2 The incidence in the UK is 2% in those aged 40 years and increases with advancing age.3,4 Thus, glaucoma increases with age and lifespan and currently accounts for at least 20% of all UK NHS ophthalmic outpatient activity.5

Case detection

The disease is often asymptomatic and case detection is dependent on patients presenting to community optometry for routine eye tests. The key to diagnosis, therefore, is the outcome at community optometry and referral to hospital eye services (HES). The three tests used to detect glaucoma are intraocular pressure (IOP) measurement, optic disc assessment, and visual field testing. Studies have shown that performing all three tests in combination gives the highest positive predictive value for glaucoma detection.6 Current community optometry practices, however, have a variety of testing strategy equipment that often differs significantly from standard hospital equipment, so that test results are not directly comparable. This, together with other factors, such as patient behaviour, has resulted in more than 50% of glaucoma cases remaining undetected in the community and a high false positive rate of referral to hospital.7,8 Of more concern, the risk of failing to diagnose glaucoma is very real, leading to late detection and, ultimately, untreated glaucoma blindness. Figure 1 (see below) shows the computerised visual field result in an eye with glaucoma left untreated for three months. Deterioration is shown by an increase in the density of black points. Glaucoma left untreated can cause blindness within 5 years.9

Figure 1: Visual field progression in the left eye in a case of untreated glaucoma over a 3-month period
July 2004
Visual field progression in the left eye in a case of untreated glaucoma over a 3-month period: July 2004
October 2004
Visual field progression in the left eye in a case of untreated glaucoma over a 3-month period: October 2004

advanced cupping and disc haemorrhage in the presence of glaucoma

Patient perspective

The implications for patients are that certain professions require near normal vision and visual field, and any degree of visual impairment is unacceptable to continue in the same role; this is particularly the case for pilots and heavy goods vehicle licence holders.10 A significant stage of the disease is when patients have to renege their driving licence because they can no longer fulfil the legal visual field requirements through the Driving and Vehicle Licence Authority.10

Older patients often have difficulty with reading, fulfilling daily activities of living, and going out independently and this can lead to depression.11,12 Conversely, there is also a relationship between cognitive impairment and glaucoma as they are both vascular neurodegenerative conditions.11,12


Glaucoma is initially treated with topical antiglaucoma medication in the form of eye drops that reduce intraocular pressure (IOP). Patients may require one to four classes of medication to achieve IOP control (prostaglandins, selective and non-selective β-blockers, α-adrenergic agonists, and carbonic anhydrase inhibitors). When medication fails, glaucoma surgery is carried out which involves creating a microscopic channel to drain aqueous fluid.4,13

The need for a guideline

Current practice in the UK is for community optometrists to perform glaucoma tests in patients at risk of glaucoma and in those who complain of possible glaucoma symptoms.7,8 The patient is referred to hospital when a positive result is obtained, however, not all of the three glaucoma detection tests are performed with consistency.8 In addition, there is also variable interpretation of the test results.7 These factors can lead to false positive referrals to hospital. Of more concern, cases of advanced glaucoma can be missed, thus resulting in late treatment for a preventable disease.7,14

Ophthalmic services in Scotland

Scotland has a unique General Ophthalmic Services (GOS) agreement (2006) which stipulates that all patients aged 40 years and over should have an IOP measurement, and those with a close family history of glaucoma should have all three glaucoma tests (IOP measurement, optic disc assessment, and visual field testing) performed.15

However, a Scottish study has reported that despite the implementation of the new GOS agreement, the quality of glaucoma referrals from community optometry to hospital needs further improvement.16 Additionally, the 2009 NICE Clinical Guideline (CG) 85 on glaucoma4 stipulated that all patients with an IOP over 21 mmHg in the absence of optic nerve damage or visual field defect should be referred to a specialist, which led to an increased number of false positive referrals from community to hospital.17

Moreover, year upon year the number of eye tests performed in Scotland has increased by about 3.5% every year, with a total increase of 232,000 from 2007 to 2011.18 This increase in eye testing has had a direct result of increased referrals for glaucoma from community to hospital.18 The Scottish Eyecare Integration project (EIP),19 also unique to Scotland, aims to electronically connect all community optometrists to hospital eye services. This allows electronic referrals to be sent with attached digital images of the optic disc.19

Despite the Scottish GOS and the EIP, Scottish optometrists were left with inconclusive guidance on which patients should be referred to hospital. Thus it was felt that the Scottish Intercollegiate Guidelines Network (SIGN) guideline would benefit all professionals involved in the care of glaucoma patients.20 The remit of the guideline was to provide guidance on assessment of patients in the community, criteria for referral to hospital, criteria for referral out of hospital (discharge), and monitoring of high-risk groups.

Scottish Intercollegiate Guidelines Network

The full SIGN methodology is outlined on the SIGN website.21 The SIGN recommendations are explicitly linked to systematic reviews and, in their absence, good practice points are made based on the expertise of the SIGN group and applicability to the region. The initial guideline is placed on the website for open review and, following an open forum meeting and further national peer review, all feedback is collated.

The final guideline incorporated all of the above processes and also took into account current NICE guidelines4 and joint recommendations from the College of Optometry and Royal College of Ophthalmologists22 in glaucoma care.

SIGN guidelines for glaucoma referral and safe discharge: the key recommendations

A full version of the guideline can be found on the SIGN website.20 Box 1 (see below) outlines a checklist for patient consultation, and Box 2 (see below) lists sources of further information and useful websites. The following are an outline of the key recommendations found in the full guideline.20

Glaucoma risk factors

The demographic and non-ocular risk factors associated with both open and closed angle glaucoma with reference to age, race, family history, diabetes, systemic hypertension, and peripheral vascular disease are quantified. This is followed by a summary of current literature that assesses the risk of glaucoma with ocular factors with specific reference to IOP, anterior chamber depth, hypermetropia, myopia, pseudoexfoliation, and pigment dispersion.

Primary care (community) examination of glaucoma suspect and ocular hypertension (OHT) patients

In connection with referral from community to HES the following examination techniques are recommended before referral:20

  • measurement of IOP—a minimum of two IOP readings on a single occasion using the same tonometer. To promote consistency across primary and secondary care services, tonometry should be performed with Goldmann or Perkins tonometers
  • optic disc assessment—discs should be examined following dilation of pupils unless there is a risk of angle closure. Detailed evaluation is recommended, taking into account disc size, vertical and horizontal cup/disc ratios, asymmetry and narrowest rim/disc ratio in line with Spaeth’s disc damage likelihood scale,23 in addition to all other signs of glaucoma. When referring patients to HES, transmission of optic disc images with the electronic referral letter is recommended
  • visual field assessment—standard automated perimetry or frequency doubling technique with a minimum of two visual fields is recommended unless the first test is unequivocal. The use of the same technology across primary and secondary care promotes direct comparison and consistency
  • the measurement of central corneal thickness (CCT)
  • the Van Herick method to assess depth of anterior chamber. Gonioscopy should only be performed by clinically experienced and competent practitioners.

Box 1: SIGN guideline for glaucoma referral and safe discharge—checklist for patient information20


  • Emphasise the importance of regular eye tests for all individuals
  • At all times, consider language and communication support needs to ensure that people with:
    • English as a second language, and/or
    • a learning disability/cognitive impairment, and/or
    • visual loss receive good quality accessible information throughout their patient journey.

Initial presentation and referral

  • Advise patients of the need for referral to a specialist and of expected waiting times
  • Explain what glaucoma is and what to expect at the appointment with the specialist
  • Reassure the patient that if the diagnosis is confirmed early, intervention can help preserve useful sight, and that with effective treatments patients are able to enjoy a good quality of life
  • Highlight the importance of attending the appointment
  • Advise patients not to drive themselves to the appointment owing to the likelihood of pupil dilation and to take a carer/friend/family member with them if possible
  • Suggest that patients note down any questions and concerns they may wish to discuss at the meeting.

Secondary eye care services

  • Explain procedures to the patient using appropriate language and level of detail to ensure comprehension
  • Discuss the importance of monitoring progression of glaucoma risk factors and emphasise that although sight lost with glaucoma cannot be recovered, adherence to treatment can preserve remaining sight
  • Provide information on, or referral to, local sight support services where appropriate
  • Allow sufficient time for answering any questions patients and carers may have, for example:
    • what does glaucoma mean?
    • what type of glaucoma do I have?
    • will I go blind?
    • will I need to stay in hospital?
    • can I still drive?
  • Where appropriate, advise patients of their rights and responsibilities in line with current DVLA requirements
  • Where appropriate, explain the Certificate of Blindness or Defective Vision and its implications
  • Consolidate verbal information on glaucoma and medication use with written information
  • Consider describing how the medication works to prevent further damage to the optic nerve
  • Point out that glaucoma often runs in families and that close family members aged 40 and over should be encouraged to book an appointment at their local optometrist to receive an NHS-funded eye health check. Early detection and treatment of the condition can preserve useful sight and quality of life well into old age.

Discharge into community

  • Provide patients with a copy of their discharge letter and clear information on who to contact should they have any concerns
  • Provide patients with written information about their condition
  • Allow sufficient time to discuss the following:
    • cleansing eyes and general eye hygiene
    • how and when to take medication
    • tuition and practice in the most appropriate instillation technique for each patient including punctal occlusion and use of devices and eye-drop aids where necessary
    • side-effects from medication
    • storing medication
  • Advise self-carers of the local support available and how to access this
  • Provide patients with information on issues regarding driving with glaucoma.

DVLA requirements

  • Emphasise the importance of attending follow-up appointments
  • Provide patients with information on eye hygiene
  • Advise patients to make a note of any questions they have and take it with them to follow-up appointments.

Scottish Intercollegiate Guidelines Network. Glaucoma referral and safe discharge. SIGN 144. Edinburgh: SIGN, 2015. Available at: www.sign.ac.uk/guidelines/fulltext/144/index.html Reproduced with permission.

Guidance criteria for referral to HES of glaucoma suspect and OHT patients20

  • Irrespective of IOP, patients with one or more of the following clinical signs should be referred to HES:
    • optic disc signs consistent with glaucoma
    • a reproducible visual field defect consistent with glaucoma
    • risk of angle closure (using Van Herick technique if the peripheral anterior chamber width is ≤25% of corneal thickness, or using gonioscopy if ≥270 degrees of posterior pigmented trabecular meshwork is not visible).
  • OHT with IOP of >25 mmHg may be considered for referral to HES irrespective of CCT
  • OHT with IOP of <26 mmHg and CCT <555 micrometers should be referred to HES if the patient is aged ≤65 years
  • OHT with IOP of <26 mmHg and CCT ≥555 micrometers may be monitored in the community.

Guidance criteria for discharge from HES to primary care20

  • Untreated OHT with IOP of <26 mmHg, CCT ≥555 micrometers and otherwise normal examination
  • Untreated OHT with IOP of >25 mmHg, otherwise normal examination and low lifetime risk of visual disability
  • Treated OHT where re-referral criteria are documented
  • Post-prophylactic iridotomy for primary angle closure, if not on topical medication and there is no evidence of glaucoma.

Patients with treated glaucoma should be monitored in HES. Discharge to locally accredited glaucoma optometrists should only be considered at the discretion of the consultant ophthalmologist, when this is in the best interest of the patient and with mutual consent. Robust arrangements should be in place for follow up, with individualised frequency of monitoring and criteria for re-referral to HES.

For the above discharge criteria, discussion and consent with the patient is required, with detailed discharge letters and re-referral to HES criteria. An exemplar discharge summary is included in the guideline, outlining all the information required for safe discharge. Close liaison with the patient’s optometrist is required and qualitative studies suggest that patients value continuity of care with the same professional.24

Box 2: Sources of further information

IGA—International Glaucoma Association

NHS Inform

  • The organisation provides quality- assured health information for the public

Royal College of Ophthalmologists

  • The Royal College of Ophthalmologists produces a range of patient booklets that can be downloaded from:

Royal National Institute of Blind People (RNIB)


  • Sightline is an online directory of services and organisations that help blind and partially sighted people in the UK

Scottish Intercollegiate Guidelines Network. Glaucoma referral and safe discharge. SIGN 144. Edinburgh: SIGN, 2015. Available at: www.sign.ac.uk/guidelines/fulltext/144/index.html Reproduced with permission.

Monitoring patients at risk of glaucoma in the community

Finally, guidance is given on monitoring patients at risk of glaucoma, with methods and frequency of examination in patients with: OHT, post prophylactic iridotomy secondary to primary angle closure, pseudoexfoliation, pigment dispersion, and optic disc anomalies (including myopic, tilted and disc drusen).20

Figure 2: Optic disc images
Optic disc drusen

optic disc drusen, a normal physiological variant

Optic disc cupping and haemorrhage in glaucoma

advanced cupping and disc haemorrhage in the presence of glaucoma


Guideline implications

The SIGN guideline has set out a pathway for assessment of glaucoma suspect and glaucoma patients in the community. It also gives guidance on which group of patients should be referred to hospital and which group can be safely followed up in the community. The patient version of the guideline gives patient information on those at risk of the disease and guidance on frequency of eye examinations and tests required.25

It is anticipated that with implementation of the guideline, patients will be detected at very early stages of glaucoma, thus eventually reducing the rates of blindness. Certain groups of patients, such as those with low risk ocular hypertensive, will receive community care. Thus it behoves general practitioners, community optometrists, and allied health professionals involved in glaucoma care to be informed of the disease and treatment pathways.

At the community optometry face of care there are implications for more refined testing equipment. Additionally, NHS Education for Scotland has agreed to support optometrists with further training to assess optic discs and appropriately interpret isolated visual field defects towards consolidating glaucoma disease recognition.26 Figure 2 (above) shows two optic disc images. One shows optic disc drusen, a normal physiological variant, whereas the other shows advanced cupping and disc haemorrhage consistent with glaucoma. These images highlight that optic disc assessment requires a certain level of clinical skills and experience.

The patient clinical audit trail

The hospital and optometry services will need to work together more closely, and possibly consider glaucoma registers, to ensure that patients, once discharged from hospital to community, are followed up and have a robust recall system for non-attenders. Traditionally, these systems are established in hospital practice but this redesign of service delivery requires community optometry to invest in similar practices.

Future research implications

To ensure appropriate uptake and implementation of the guideline, areas of future research would be beneficial. These include: the assessment of the number of patients with complete referral information, the number of false-positive referrals, the number of patients presenting with advanced glaucoma, and the re-referral rate of patients discharged to community care.

Limitations of the guideline

While there are several global guidelines on the management of glaucoma,4,13,27 there is no systematic review evidence that studied the effectiveness of referral or discharge criteria between primary and secondary care providers. Thus, the patient pathways are following good clinical practice points based on the HTA on surveillance for ocular hypertension,28 NICE CG85 on glaucoma,4 joint guidance from the Royal College of Ophthalmologists and College of Optometry,22 and the expertise of the SIGN group.


This is the first guideline to specifically address the referral and discharge of glaucoma suspect, ocular hypertensive, and glaucoma patients between primary and secondary care. It is hoped that patients will receive a comprehensive testing service in the community to detect glaucoma at the earliest stage. However, this is still dependent on patients presenting independently or as a consequence of referral from health professionals to have an eye test. Refining the quality of clinical information of patients referred to, and out of, hospital reduces the false-positive rate, thus ensuring that all hospital resources are directed towards patients who require timely treatment. Identifying patients for safe community care makes full use of community care services, saves hospital resources under pressure, and is often practically more acceptable to the patient, providing the regulatory service infrastructure is in place for safe practice.29

Key points

  • Glaucoma is a leading cause of preventable blindness in the UK
  • Those above the age of 40 should have regular eye tests as community optometry is empowered to carry out investigations for case detection
  • Those with a family history and other systemic and ocular risk factors for glaucoma should have annual eye tests
  • All medical and allied health professionals should consider referring patients for an eye test where there is a suspicion of glaucoma
  • Elderly patients, particularly those with any degree of cognitive impairment, require other professionals to direct them towards an eye test
  • Patients can go blind within 3 years of untreated glaucoma
  • Patients should have all three glaucoma tests (IOP measurement, optic disc assessment, and visual field testing) before referral from community to hospital
  • Patients discharged from hospital to community care need regulated follow up with optometry
  • Patient consent and choice should be key to all of the above arrangements
  • Exemplar referral information and discharge letter information is included in the guidelines.

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GP commissioning messages

written by Dr David Jenner, NHS Alliance GMS contract/PBC Lead

  • Glaucoma is a very common condition accounting for a large proportion of specialist ophthalmology activity, especially long-term follow up in outpatients
  • Community optometry is currently commissioned by NHS England whereas secondary care activity is commissioned by CCGs
  • Responsibility for commissioning community optometry should be clearly defined when CCGs are taking on delegated or shared co-commissioning of primary care
  • CCGs and NHS England together with the local optometry committee and secondary care providers should agree a local care pathway for glaucoma care including specifications for screening and clear indications for hospital referral
  • CCGs should explore the potential for community optometry follow up of stable glaucoma, which could prove more convenient to patients, more cost effective with discounts against the PbR tariff, and relieve pressure on hospital out patients
  • CCGs could work with local optometrists and departments of public health to run glaucoma awareness campaigns to promote regular eyesight testing for those over 40 years of age or those with a family history of glaucoma
  • Tariff costs for ophthalmology outpatients: £104 (new), £59 (follow up).a

CCG=clinical commissioning groups; PbR=payment by results

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