terminology and guidelines for glaucoma ii - Kwaliteitskoepel

3.2 - TARGET IOP AND QUALITY OF LIFE
3.2.1 - THE TARGET INTRAOCULARPRESSURE (TARGETIOP)
Definition: an estimate of the mean IOP obtained with treatment that is expected to prevent further glaucomatous
damage. It is obviously difficult to assess accurately and in advance the IOP level at which further damage may occur
in each individual patient and individual eye (see Ch. Introduction II). There is no single IOP level that is safe for
every patient. However, it is generally assumed in glaucoma that aiming to achieve at least a 20% reduction from the
initial pressure at which damage occurred or in advanced glaucoma to lower the IOP to a level below 18 mmHg at all
visits is a useful way to achieve the initial target IOP 14 . In individuals with elevated IOP between 24 mm Hg and 32
mm Hg in one eye and between 21 mm Hg and 32 mm Hg in the other eye, topical ocular hypotensive medication
was effective in delaying or preventing the onset of POAG when the IOP was reduced by 20% or an IOP of 24 mm
Hg or less was reached 15 . This does not imply however that all patients with borderline or elevated IOP should receive
medication. A study comparing treatment vs no treatment in early glaucoma 16-17 showed that lowering the IOP by
25% from baseline determined a 45% decrease in the risk of progression. Patients with POAG with baseline pressures
below 30 mm Hg could have a management plan that allows initial observation before treatment to assess the rate of
change 16,17 (see Ch. Introduction II). Such an approach is different from the Target Pressure oriented initial approach
to POAG and presupposes a monitoring system that allows recognition of change.
The least amount of medication and side effects to achieve the therapeutic response should be a consistent goal
(see FC VI).
The target IOP varies according to:
• IOP level before treatment
• The overall risk of IOP-related optic nerve damage, which depends on
* average IOP
* maximum IOP
* fluctuations of IOP
In case of doubt, consider performing 24 hour or diurnal phasing to identify IOP spikes
• Stage of glaucoma
The greater the pre-existing glaucoma damage, the lower the target IOP should be.
In eyes with severe pre-existing damage, any further damage may be functionally important.
• Rate of Progression (RoP) of glaucomatous damage
Progressive damage is more likely with higher IOP, more severe pre-existing damage and more risk factors.
• Age of patient
• Life expectancy of patient
• Presence of other risk factors
A lower IOP may be needed if other risk factors are present
Target IOP may need adjustment during the course of the disease
Periodic re-evaluation of individual target IOP considering:
* Efficacy
* Cost vs benefits
If the visual field continues to worsen at a rate that is clinically significant, it may be necessary to aim for a lower target
IOP. With the re-evaluation it is important to exclude other risk factors, such as systemic hypotension, poor
compliance or IOP spikes 12-22 .
Although some benefit can be derived from lowering the IOP even if the target pressure is not reached, the efficacy
on the outcome must be assessed carefully in each individual.
Unfortunately one of the limitations of the target IOP approach is that we only know with hindsight whether the target
pressure selected initially was adequate or not. In other words a patient must get worse before we verify that the
target pressure was inadequate.
Ch. 3 - 5 EGS