Physicians discuss validity of monocular treatment trial for glaucoma medication

Should physicians abandon the monocular treatment trial for assessing the efficacy of a glaucoma medication? That was the question debated in a point-counterpoint session during the glaucoma subspecialty day meeting.

M. Bruce Shields, MD, a proponent for the monocular treatment trial, explained that the monocular treatment "hinges in the historically accepted assumption that the pressures in the fellow eyes rise and fall in sync, so that the response of one eye can be predicted by that of the other."

However, he acknowledged that a number of studies seem to support the observation that asymmetric IOP fluctuation does occur, including a study by Tony D. Realini, MD, who disagreed that the monocular trial is useful and should be continued.

"Starting a medication simultaneously in both eyes would not eliminate the problem of asymmetric IOP fluctuation," Dr. Shields emphasized. "It would only reduce the chances of assessing how the drug is actually working."

He offered several advantages of the monocular trial, including better assessment of ocular adverse reactions when tried first in one eye, a safer approach with half as much given initially, and a better strategy in dealing with patients.

Dr. Realini countered with four assumptions that he showed to be false.

• Fellow eyes exhibit symmetrical spontaneous IOP fluctuations.

• There is no contralateral crossover effect from monocular treatment with a topical IOP-lowering agent.

• Fellow eyes respond symmetrically to a given medication.
  
• Patients take their medications as directed.

Dr. Realini believes in obtaining several IOP measurements before starting glaucoma medication to determine the baseline IOP; then he will proceed with the glaucoma therapy in both eyes.

Eve J. Higginbotham, MD, moderated the session.