NHMRC Glaucoma Guidelines - ANZGIG

NHMRC GUIDELINES FOR THE SCREENING, PROGNOSIS, DIAGNOSIS, MANAGEMENT AND PREVENTION OF GLAUCOMA
Chapter 8 – Monitoring: long-term care
Intraocular pressure
A specific target IOP should be established for each patient at diagnosis. A primary purpose of any
review is to assess whether this target has been achieved, and whether there is evidence of glaucoma
progression. This provides a basis for continuing or changing the glaucoma management plan.
IOP is generally measured in the sitting position, although occasionally a supine measure is useful.
IOP can vary during the day and night and therefore diurnal curves for IOP are valuable. Recording
the time of IOP measurement at each contact with a health care provider allows practical clinical
assessment of daytime diurnal variation. Useful information regarding glaucoma progression at
apparently low IOP levels may be gained from one to two hourly IOP measurements over a
12 to 24 hour period. Attention needs to be given to glaucoma treatments that are effective over
24 hours (AOA 2002).
Recent independent evidence shows better field preservation with smaller diurnal fluctuations in
IOP (European Glaucoma Society [EGS] 2003, citing the Advanced Glaucoma Intervention Study
[AGIS] Investigators).
In clinical practice, a patient’s target pressure is that which is judged by the health care provider to
have the best probability of limiting disease progression. The goal is to achieve it, or to approach it
with minimal treatment-induced adverse effects on quality of life. Thus exact margins for failure to
achieve target IOP cannot be precisely defined, and the IOP measurement error is approximately
1–2 mmHg. The target IOP is often recorded as an acceptable range of IOPs rather than a single
IOP value. Target IOP serves as a guide, which may be changed according to clinical need.
When target IOP is achieved, but there has been progression in damage to optic nerve or retinal
nerve fibre layer structure and function, a further 20% reduction in IOP should be planned
(Canadian Glaucoma Study Group 2006), provided non-adherence to treatment regimens between
visits has been excluded as a cause. Further factors that should be considered when reviewing
the target IOP include the patient’s quality of life within the current management regimen, new
systemic or ocular conditions and the risk:benefit ratio of the medication management required
to achieve the target IOP.
Evidence Statements
• Evidence strongly supports assessing target intraocular pressure at each ocular review, within the context
of glaucomatous progression and quality of life.
• Evidence strongly supports a further 20% reduction in target intraocular pressure when glaucomatous
progression is identified.
Point of note
Evidence supports the use of information on diurnal intraocular pressure curves. These are valuable
in identifying fluctuations in intraocular pressure, and could contribute to a clearer picture of risk for
patients with normal tension glaucoma.
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