››Lack of adherence and persistence with medication regimens may induce significant short and long term fluctuation.

13.8  How Aggressive Should I Be

in Eliminating Long-Term IOP

Fluctuation Given the Potential

Complications of Medications

and Surgery?

13.7  What is the Impact of Surgery on Short-Term and Long-Term IOP Fluctuation?

It has been demonstrated that argon laser trabeculoplasty decreases mean short-term IOP fluctuation by 30% when compared to pretrabeculoplasty IOP [31]. Other studies have confirmed this finding [32, 33]. However, such a reduction, while important in absolute numbers of mmHg, may not reflect a significant change in percent reduction relative to IOP peak or trough since these values are reduced by the treatment as well.

Several studies have addressed the question of whether IOP fluctuations are best controlled by medical therapy or incisional surgery. They have found that shortterm IOP fluctuation is best controlled with surgical therapy [34–36]. Intraocular peak pressure and shortterm IOP fluctuation measured following water-­ provocative testing were significantly greater in 30 patients with POAG using ocular hypotensive medication and no history of glaucoma-related surgery as compared to 30 such patients who had undergone one or more trabeculectomies (p < 0.05 for both comparisons) [35]. Similarly, a prospective observational study in 60 patients found that a well-functioning trabeculectomy provided a statistically lower mean, peak, and range of IOP over the 24 h day than the maximally-tolerated medical therapy in patients with advanced glaucoma ( p £ 0.0001 for each comparison) [34].

In terms of long-term IOP fluctuation, filtration surgery has been shown to enhance the effect of reducing IOP changes as compared to ocular hypotensive medications [37].

Given conflicting study results, an international expert panel was convened to determine the degree of consensus among glaucoma specialists concerning the measurement, characterization, and potential implications of IOP and the impact of shortand long-term fluctuation [38]. Through a modified Delphi process to assess both the presence and strength of consensus, the panel agreed that adequate means of IOP measurement exist, although the frequency at which IOP should be measured is poorly defined. The need to additionally investigate the role of IOP changes in glaucoma management was highlighted by the indeterminate and nonconsensus ratings among experts about the impact of long-term and short-term IOP fluctuation.

Furthermore, while the current weight of evidence may support long-term fluctuation as an important factor to consider, it is important to remember that long-term IOP fluctuation may also be a marker for treatment success or failure. For example, in patients on medications, IOP fluctuation may indirectly show how adherent and persistent patients are to medications. In those patients that have undergone glaucoma surgery where there is increasing IOP fluctuation, the fluctuation may actually indicate that the surgery is failing.

As such, the central consideration when recommending treatment is to take into account a patient’s life stage, needs, and expectations. By involving the patient in decision-making and surveying their preferences, ophthalmologists can best meet their obligations to “first do no harm.”

Summary for the Clinician

››Several studies have addressed the question of whether IOP fluctuations are best controlled by medical therapy or incisional surgery and have found that short-term IOP fluctuation is best controlled with surgical therapy.

Summary for the Clinician

››Through a modified Delphi process, a panel of experts could not come to a consensus regarding the importance of IOP fluctuation in glaucoma.

››Long-term IOP fluctuation may be a marker for how adherent and persistent patients are to medications and the success of surgery.