Interpretation of uniocular and binocular trials of glaucoma medications: an observational case series

<p>Abstract</p> <p>Background</p> <p>To predict the effectiveness of topical glaucoma medications based on initial uniocular and binocular treatment. To test a traditional hypothesis that effectiveness following a uniocular trial is associated with the change in IOP in the initially treated eye minus the change in the initially untreated eye. To determine whether uniocular or binocular treatment trials are superior.</p> <p>Methods</p> <p>Based on a review of medical records, we identified 168 instances in 154 patients with bilateral primary open angle glaucoma of initial uniocular use of a topical glaucoma medication with well-documented intraocular pressure (IOP) readings at baseline (IOP_A), during the trial (IOP_B), and at follow-up (IOP_C). Abstracted data included demographic data, IOP, and medication use. Predictors of the IOP following the trial (IOP_C) in each eye were identified by multivariable linear regression. In 70 cases, the predictive ability of initial uniocular and binocular treatment could be directly compared.</p> <p>Results</p> <p>In a multivariable analysis, the follow-up pressure in the initially treated eye (IOP_1C) was directly correlated with treated eye IOP during initial uniocular use (IOP_1B, p < 0.001). In a multivariable analysis, the follow-up pressure in the initially untreated eye (IOP_2C) was directly correlated with its baseline IOP_2A(p < 0.001), and also tended to be associated with treated IOP_1B(p = 0.07). The multivariable regression coefficient (b) for the IOP change in the initially untreated eye was generally not close to the value of -1 expected by the classic teaching (for eye 1, b = 0.04, p = 0.35; for eye 2, b = 0.07, p = 0.50). In 70 cases, the uniocular and binocular trials predicted a similar fraction of the variance in follow-up IOP_1C(r²= 0.56 and 0.57, respectively) and IOP_2C(r²= 0.39 and 0.38, respectively).</p> <p>Conclusion</p> <p>1) For uniocular trials, the IOP change in the untreated eye should not be subtracted from that in the treated eye. 2) Uniocular and binocular trials have similar predictive value when interpreted correctly. Either may be selected based on clinical circumstances.</p

The Utility of the Monocular Trial

OBJECTIVE: To determine whether adjusting the intraocular pressure (IOP) change of the trial eye for the IOP change of the fellow eye (i.e., the monocular trial) is a better assessment of medication response than testing each eye independently. DESIGN: Analysis of data from a prospective, randomized clinical trial. PARTICIPANTS: Two hundred and six participants with ocular hypertension randomized to the observation group and later started on a topical prostaglandin analogue (PGA). METHODS: Participants were instructed to instill a topical PGA in one eye once daily and returned in 4–6 weeks to determine medication response. IOP response of the trial eye was determined by the IOP change between baseline and 1 month in the trial eye alone (unadjusted method) and by adjusting for the IOP change in the fellow eye between the same visits (adjusted method). We defined our “gold standard” for medication response as the IOP change in the trial eye using up to 3 pre- and 3 post-treatment visits on the same medication. Pearson correlation was used to compare the unadjusted and adjusted methods to the gold standard. In addition, symmetry of IOP response between trial and fellow eyes to the same medication was determined by correlating the IOP change of the trial eye using up to 3 pre-and 3 post-treatment visits to the IOP change of the fellow eye between the same visits. MAIN OUTCOME MEASURES: Correlations of IOP change of the trial eye using the gold standard to the IOP change of the trial eye using the unadjusted and adjusted methods. RESULTS: The correlations of IOP change using the gold standard to the IOP change using the unadjusted and adjusted methods were r=0.40 and r=0.41, respectively. The correlation of IOP change of both eyes between the same pre-and post-treatment visits was r=0.81. CONCLUSIONS: The monocular trial (i.e., adjusted method) appears equivalent to testing each eye independently (i.e., unadjusted method) however neither method is adequate to determine medication response to topical PGAs. Both eyes have a similar IOP response to the same PGA. Further studies to understand IOP fluctuation are necessary to improve current methods of assessing medication response

Tight orbit syndrome: A previously unrecognized cause of open-angle glaucoma

Purpose: To describe a new syndrome of tight orbit and intractable glaucoma with a poor visual prognosis