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  • You must carry out relevant tests when examining a patient who is in an at-risk group for glaucoma.
  • Those with a greater than average risk include certain ethnic groups, patients with first degree relatives with glaucoma and those over 40.
  • In England, patients whose IOP is 24mmHg or greater should be treated.
  • You should follow local protocols if you are participating in community services.
This Guidance does not change what you must do under the law.
When examining a patient who is in an at-risk group for glaucoma, you must carry out relevant tests.99 Guidance varies across the UK.100, 101, 102 You should be familiar with the relevant guidance and the thresholds at which further tests should be undertaken. If local protocols apply you should comply with these.
Glaucoma can be difficult to detect in the early stages and you should stay up to date with current thinking on the pathophysiology, clinical signs and diagnostic techniques required to detect it. 
You will identify the majority of patients who are at risk from chronic open angle glaucoma during a routine eye examination. They are principally patients with one or more of the following: 
  1. optic disc features suggestive of glaucoma
  2. loss of peripheral vision
  3. high IOP.
Even in the absence of the signs or symptoms in the paragraph above, patients at greater than average risk of primary open angle glaucoma include those:103
  1. in certain ethnic groups, for example African-Caribbean people
  2. with first degree relatives with glaucoma
  3. over the age of 40. The risk increases with every decade of life thereafter
  4. with thinner corneas
  5. with myopia (myopia >6D is associated with an increased risk)
  6. with diabetes
  7. with systemic hypertension
  8. taking topical or systemic steroids, as they may develop steroid-induced glaucoma.
The signs of asymptomatic chronic angle closure glaucoma are almost identical to those of chronic open angle glaucoma with the exception that the anterior chamber angle is capable of intermittent closure or being obstructed.
The prevalence of angle closure glaucoma is greater than that of chronic open angle glaucoma (COAG) in people of South or East Asian descent. 
You should be familiar with signs and symptoms of primary open angle glaucoma, including that around 40% of patients with glaucoma have IOP below 21mmHg.104
Assessment of the central visual field may provide useful diagnostic information and complement the examination of the optic nerve head. Visual field findings should fit with optic disc findings. For example, if examination shows an inferior optic disc notch, you would expect to see a superior field defect. You should consider which visual field program is clinically indicated.
Visual field examination may sometimes produce anomalous results. However, you should not underestimate the usefulness of baseline measures and ongoing comparisons. Structural ocular imaging (such as an OCT) is not considered a robust substitute for a visual fields assessment. However, the complimentary use of functional (visual fields) and structural (OCT) assessments may help improve the sensitivity and specificity of detecting COAG. 
Patients with raised IOP are at increased risk of developing glaucoma. Where pressures are borderline, you should repeat the test, noting the time of day of each test. NICE recommends105 that patients whose IOP by contact applanation tonometry is 24mmHg or higher should be:
  1. formally diagnosed with ocular hypertension by a healthcare practitioner who has appropriate training or qualifications
  2. treated, as they are at greater risk of developing glaucoma
SIGN recommends that patients with IOP >25mmHg may be considered for referral to the HES.
You should be aware of the signs and symptoms of other forms of glaucoma, such as acute or sub-acute narrow angle glaucoma or secondary glaucoma, due, for example, to pseudoexfoliation syndrome or pigment dispersion syndrome.
You should select additional procedures to those in the routine eye examination, according to the patient’s clinical need. You should normally: 
  1. assess the optic nerve head. This would include assessing the size of the disc
  2. measure the IOP. See section on the use of non-contact tonometry.
If a patient refuses to consent to tonometry after you have explained the reason for this procedure, you should record the patient’s reason for refusal. You should use your professional judgement to decide how best to manage the patient.
The examination may also include an assessment of the central visual field using perimetry with threshold control. Where necessary, you should repeat visual field assessment to obtain a meaningful result.
If the patient is at risk from glaucoma, you should assess the anterior eye and angle, for example by slit lamp – Van Herick technique. You should also look for signs of pigment dispersion syndrome (PDS) and pseudoexfoliation (PEX).
Optic nerve head imaging, including photography and OCT, may be helpful for the assessment and detection of abnormal structural changes to the optic nerve head. You should stay up to date with the evidence and be cautious about management decisions based on imaging alone.
You should follow local protocols and referral filtering pathways for people presenting with ocular hypertension or evidence of glaucoma.
It is good practice to follow up equivocal results from non-contact tonometry with contact applanation tonometry. If you are using non-contact tonometry, before considering referral you should take four readings per eye. In England, Wales and Northern Ireland, in the absence of other signs of glaucoma, you should refer the patient for further assessment only when the mean of the IOP readings is 24mmHg or above. You should advise people with IOP below 24mmHg to continue with their routine eye examinations. In Scotland you should follow SIGN guidelines. 
In England, unless clinical circumstances indicate that urgent or emergency referral is indicated, patients should have referral filtering before they are referred to the HES. For these non-urgent patients, you should only refer without referral filtering if there are no such local arrangements. Referral filtering is where the patient has additional tests done. These may be repeat measures, referral refinement or enhanced case finding.106 In Scotland you should follow SIGN guidelines.
If you are participating in a community service you should follow local protocols where they differ from this guidance. 
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