Page 47 - CJO_F17_GLAUCOMA_SUPPLEMENT

MANAGING OPEN ANGLE GLAUCOMA

Clinical Recommendations for initiating treatment:
• Consider all risk factors and treatment options and review options with each individual.
• Consider risks versus benefits for all treatment options.
• Document all counselling diligently.

IOP LOWERING FOR GLAUCOMA
IOP lowering remains the only clinically established method to slow the progression of glaucoma. Recall that not all
of those with elevated IOP (ocular hypertension; OHT) develop glaucoma, and not all with glaucoma have elevated
IOP. Therefore, treatment for open angle glaucoma is not usually initiated until a threat to visual function has been
identified. This may be when confirmed structural damage to the optic nerve or functional loss of visual field is
noted, or when an individual with a high-risk profile for the development of glaucoma is identified. Ultimately, the
goals of treatment should include being cognizant of a person-centred model to balance the goals of the individual
and their life expectancy with their risk profile, always mindful of maintaining functional vision for daily activities
and maximizing health-related quality of life (HRQoL).
A variety of drug classes with multiple agents in each class are now available for the medical management of glau-
coma. Further, new molecules and novel delivery systems are being actively investigated and these are likely to alter
our current treatment algorithms in short order.

The effectiveness and limitations of IOP-lowering treatments have been well established in various randomized
clinical trials. 61,290 These factors will be considered separately in each class of medication.

TARGET PRESSURE
Before starting treatment, a clear management plan should be developed that includes deciding on a “target”
intraocular pressure. Target pressure represents the initial IOP anticipated to stabilize the progression of the
disease to a point that it will reduce the risk to visual function. Target IOP is unique to each individual patient,
and indeed, unique to each individual eye. Randomized control clinical trials inform our decision-making and
highlight the importance of setting a target IOP that best reflects the stage of the disease and the likelihood
of minimizing progression. 8,14,15 In truth, however, there is no way to be certain that maintaining the target
IOP will achieve that goal. Indeed, the target pressure is merely a mathematical construct using a ‘best guess’
scenario, and analysis of long-term, repeated measures of structure and function is the only way to truly de-
termine the rate of progression for an individual patient, which in turn determines whether the target IOP
was adequate. However, setting a target pressure remains a helpful starting point, establishing a reasonable
value from which critical re-evaluation can be assessed over time. Accordingly, it is important to bear in mind
that a target pressure is a dynamic value. If the measured IOP is not reaching target but minimal to no signs of
progression are detected, then it is not likely necessary to adjust treatment to reach that pre-determined value.
Similarly, whether the measured IOP is or is not at target is irrelevant if clinically significant disease progres-
sion is determined. In the case of progression, careful consideration to adherence to treatment should be
308
attended to before alterations to therapy are made. A simplified flow chart highlighting an appropriate way
38
to utilize target IOP can be seen in figure 15.
There are limitations to the use of the target pressure construct. As previously noted, many patients have a peak
IOP that is not measured within office hours. This consideration is not only important for the determination of the
38
target pressure, but larger fluctuations in IOP have been associated with disease progression and must always be
kept in mind when analyzing data. 38,149

CANADIAN JOURNAL of OPTOMETRY | REVUE CANADIENNE D’OPTOMÉTRIE VOL. 79 SUPPLEMENT 1, 2017 47