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  • IOP Variations and RNFL Thinning in OAG

    By Jean Shaw
    Selected and reviewed by Neil M. Bressler, MD, and Deputy Editors
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    Journal Highlights

    JAMA Ophthalmology, December 2022

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    Nishida et al. set out to investigate the association of mean IOP and IOP variability with the rate of retinal nerve fiber layer (RNFL) thinning over time in patients with open-angle glaucoma (OAG). They found that IOP variabil­ity was independently associated with structural change in these patients, even after adjustment for mean IOP.

    For this retrospective analysis, the researchers evaluated 508 patients (815 eyes) who had participated in two longitudinal studies and had at least four visits and two years of follow-up with OCT and IOP measurements. The patients’ mean age was 65.5 years (SD, 11 years), and the majority were female (55.1%) and White (55.3%). Of the 815 eyes, 564 had perimetric and 251 had preperimetric glaucoma. A linear mixed-effect model was used to inves­tigate the association of IOP parame­ters with the rates of RNFL thinning. Dominance analysis was performed to determine the relative importance of the IOP parameters. Eyes were catego­rized into groups (fast, medium, and slow progressor) according to their rate of RNFL thinning.

    During follow-up (mean, 6.3 years), mean IOP was 14.8 mm Hg, peak IOP was 18.8 mm Hg, IOP fluctuation was 2.4 mm Hg, and IOP range was 7.4 mm Hg. All IOP measurements were highest for the fast progressor group. With regard to RNFL change, the mean rate was –.67 per year (95% CI, –.73 to –.60)—and in multivariable models adjusted for mean IOP and other con­founding factors, a faster annual rate of RNFL thinning was associated with a higher SD of IOP. Among the portion of change that could be attributed to IOP measurements, IOP fluctuation had a greater impact than did mean IOP.

    In their discussion, the authors note several limitations of this analy­sis—for instance, they did not exclude patients who showed signs of disease progression and may have received glaucoma-lowering drugs. Nonetheless, they suggest that the addition of IOP variations to mean IOP measurements may have clinical utility. (Also see related commentary by Paul F. Palmberg, MD, PhD, in the same issue.)

    The original article can be found here.