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Editors Selection IGR 8-1

Medical Treatment: IOP lowering does not affect VF status in the short term, study finds

Comment by Boel Bengtsson & Anders Heijl on:

The idea that visual field status can improve after IOP reduction has often been raised, and several publications have supported this view, as recently summarized in a review paper.¹ It has even been suggested that the lack of such an improvement may indicate that the IOP reduction might be non-optimal.² It is, however, important to realize that visual field status can improve over time in untreated eyes, so-called perimetric learning,³ and studies claiming improvement in visual field status as a result of IOP reduction, therefore, need to be controlled, for instance by including a group that has not been subjected to IOP lowering therapy during the study period.

The United Kingdom Glaucoma Treatment Study (UKGTS) was controlled in this way, and its authors have analyzed data from that study to address the question of whether visual field status really can improve after introducing pressure-lowering therapy. In the UKGTS, untreated patients with newly detected glaucoma were randomized to treatment with latanoprost or placebo. The authors compared the baseline visual fields of the two groups to follow-up visual fields obtained an average of 3 months later. Changes in Mean Deviation were almost the same in the two groups. Further, there was no difference in the proportions of patients with MD improvements of 1 dB or more, and there was no association between MD change and IOP reduction. Stratifying data by IOP, level of VF loss or age also did not reveal any differences, nor did pointwise analyses.

Medical IOP reduction in early glaucoma did not result in an improvement of visual field status

The authors’ conclusions are well supported by data in this carefully designed study, and their results convincingly show that medical IOP reduction in early glaucoma did not result in an improvement of visual field status. This is in accordance with previously published results from the Early Manifest Glaucoma Trial.⁴

As the authors point out, strong evidence requires agreement in results from two independent well-designed studies. We agree with the authors’ opinion that there is now strong evidence that VF sensitivity, as measured by SAP, does not improve as a result of medical IOP lowering, and this issue can be put to rest.

The UKGTS and EMGT results do not, however, provide evidence that no improvement can be seen after more dramatic, for instance, surgical reductions of IOP in glaucoma patients with very high intraocular pressures.

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