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  • Achieving Target IOP Slows VF Decline

    By Lynda Seminara
    Selected by Stephen D. McLeod, MD
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    Journal Highlights

    Ophthalmology, January 2022

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    In a longitudinal study, Villasana et al. looked at the effect of achieving clinician-established IOP targets on visual field (VF) status. They found that failure to attain IOP goals coincides with VF worsening and that eyes with moderate glaucoma have the greatest rate of VF decline.

    This retrospective study included 1,688 patients (2,852 eyes) with sus­pected or confirmed glaucoma who were treated in a tertiary care practice. For all eyes, data were available for at least five reliable VF tests and five IOP measures. Each eye had a target IOP, established by the clinician in the pa­tient’s first or second visit for glaucoma care. In general, the clinicians followed published guidelines for target IOPs: values in the low teens for eyes with advanced disease, the mid-teens for moderate disease, and the high teens for mild disease.

    The primary dependent variable was the slope of mean deviation (MD) over time (dB/year), and the main independent variable was mean differ­ence between actual and target IOP values. Linear regression models and mixed-effects linear models were used to explore the relationship between MD slope and mean difference from target for each eye. The mixed models includ­ed an interaction term to account for disease severity (mild/suspect, mod­erate, advanced) and a spline term to account for difference between success and failure to attain the IOP goal. The main outcome measure was the rate of change in MD slope for each 1-mm Hg difference from the target IOP.

    In the overall analysis, a difference (increase) of 1 mm Hg from the goal IOP corresponded to a –.018 dB/year effect on MD slope (p < .05). In eyes with moderate glaucoma, each 1-mm Hg increase from the target value was associated with an MD slope of .119 dB/year (p < .05). The effect of missed IOP on VF decline was more profound than the effect of absolute IOP on VF decline, for which each 1-mm Hg increase in IOP had an effect of –.004 dB/year on the MD slope (p > .05). Achieving target IOP led to a lower likelihood of VF loss in comparison to achieving any arbitrarily defined target not set by the clinician, as long as the goal IOP was <21 mm Hg for mild or suspected glaucoma and <18 mm Hg for moderate glaucoma.

    In light of these findings, the differ­ence between actual and target IOP may be a predictor of VF decline, said the authors.

    The original article can be found here.