Original article
A Comparison of Long-term Intraocular Pressure Fluctuation in Patients Treated With Bimatoprost or Latanoprost

https://doi.org/10.1016/j.ajo.2008.04.030Get rights and content

Purpose

To evaluate long-term intraocular pressure (IOP) fluctuation in patients with glaucoma or ocular hypertension treated with bimatoprost or latanoprost.

Design

Post hoc analysis of prospectively collected data from a previously reported multicenter, investigator-masked, randomized clinical trial of bimatoprost and latanoprost.

Methods

Patients were treated bilaterally with bimatoprost (n = 133) or latanoprost (n = 136) for six months. IOP measurements were taken at 8 am, 12 pm, and 4 pm at baseline, week 1, and months 1, 3, and 6. Long-term IOP fluctuation during treatment was determined as the standard deviation (SD) of all 12 follow-up measurements.

Results

There was no significant between-group difference in short-term daily IOP fluctuation at baseline. Long-term IOP fluctuation over six months of treatment [mean SD (range SD)] was 1.9 (0.5 to 6.3) mm Hg with latanoprost vs 1.7 (0.5 to 3.9) mm Hg with bimatoprost (P = .050). Latanoprost-treated eyes were more likely than bimatoprost-treated eyes to have long-term IOP fluctuation of ≥3 mm Hg (7.8% vs 2.5% of eyes; P = .009).

Conclusions

Bimatoprost-treated eyes demonstrated less long-term fluctuation in IOP compared with latanoprost-treated eyes in this six-month study. Additional studies are needed to confirm these findings and to determine their impact on glaucomatous progression.

Section snippets

Methods

The analysis was performed on data collected in a previously reported randomized, prospective, multicenter, investigator-masked clinical trial comparing bimatoprost and latanoprost.15 Inclusion criteria for the study were patients with either glaucoma or OHT and baseline IOP (8 am) following appropriate washout between 22 mm Hg and 34 mm Hg in each eye. There were no significant differences between treatment groups in patient age, gender, race, iris color, diagnosis, or need for washout.

Baseline Intraocular Pressure

Baseline analyses included 266 eyes in the bimatoprost group and 272 eyes in the latanoprost group. The untreated baseline mean IOP at each hour for eyes in the bimatoprost and latanoprost groups is shown in the Table. At 8 am and 4 pm, the two groups were comparable with respect to mean IOP. At 12 pm, mean IOP was higher in the bimatoprost group compared with the latanoprost group. Short-term daily fluctuation in IOP at untreated baseline was similar between the two groups (Table).

Intraocular Pressure Fluctuation During Treatment

The number

Discussion

Elevated IOP remains the predominant risk factor for glaucoma. While the EMGT analysis revealed only mean IOP as a factor leading to progression, a number of recent studies have suggested that fluctuation in IOP may also serve as an independent risk factor for glaucomatous VF progression.1, 2, 7, 10, 11 The recent study by Hong and associates7 demonstrates that in patients with relatively low and well-controlled IOP, IOP fluctuation may play a role in leading to progression. Within this

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      Konstas and associates have reported studies evaluating the 24-hour range of IOP during treatment with a variety of IOP-lowering medications.25–29 Analyses of data from previously reported studies have further compared the effectiveness of various prostaglandin analogs in controlling short-term or long-term IOP fluctuation.30,31 As IOP fluctuation may have an important effect on VF progression and patient outcomes, we recommend that analyses of data from additional comparative studies be performed to evaluate IOP fluctuation as well as mean IOP levels with available IOP-lowering medications.

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      The impact of such differences on progression awaits further research. The role of long-term IOP fluctuation in progression of glaucoma and ocular hypertension remains unclear, at least in part because of differences among studies in their designs, patient populations, and durations of follow-up.6–8,19,21–24 Long-term IOP fluctuation measured by the intervisit range has a biologically reasonable relationship to glaucomatous progression in that homeostatic mechanisms may be disrupted, creating intermittent unevenness on the optic nerve.12

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