Page 22 - 21st Century Perspective - Glaucoma Supplement

The Monocular Therapeutic Trial

The monocular trial has been both endorsed and maligned over the years, yet the consensus of
expert study and opinion solidly supports this management maneuver; we have found it to be highly

complementary to our care of patients with glaucoma over the decades.

Note that timolol exerts a slight crossover effect, such that the untreated eye will demonstrate about
20% of the effect seen in the treated eye. This behavior needs to be taken into consideration when
assessing efficacy. The other commonly used glaucoma medications do not demonstrate such a
crossover effect.

Our standard approach with monocular trials is to provide a sample of the intended drug to be used
in the eye with the highest baseline IOP or in some cases, in the eye with more advanced optic

nerve head damage.

Optometrists should thoroughly discuss with the patient that the sole purpose of the medication is to
reduce the pressure inside the eye, and that he or she will not feel any differently or see any better
while using any topical glaucoma drop. Explain to the patient that the only way to tell if the drug is of
benefit is to remeasure the eye pressure at an appropriate interval. If a meaningful reduction is
achieved, then ask the patient to continue using the drop indefinitely and almost always in both eyes.

By performing this monocular trial, optometrists can avoid being led astray by physiological diurnal
fluctuations ​(Figure 13)​.

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