A recent study published in the British Journal of Ophthalmology found that the location, size and volume of visual field (VF) defect clusters on an initial test can help predict which defects are likely to recur on future tests, aiding earlier and more reliable identification of glaucomatous damage.¹

Standard automated perimetry (SAP) is a key tool for diagnosing and monitoring glaucoma, but its subjective nature and inherent variability can make it challenging to distinguish true visual field (VF) loss from test fluctuations.^2,3  The aim of this study was to determine whether specific characteristics of cluster defects seen on an initial visual field (VF) test. such as their location, size, and depth, could predict repeatability on subsequent tests, particularly in patients with suspected or early glaucoma.

The researchers analysed data from 197 eyes using initial VF pattern deviation plots to identify clusters of abnormal test points. They assessed cluster characteristics including size (number of adjacent abnormal points), volume (sum of total deviation values within a cluster), and location (central versus peripheral rim). Among the 4,424 points initially flagged as abnormal at the p<5% level, only 26.9% were repeatable on two follow-up tests.

Clusters with greater size and volume were significantly more likely to represent true, repeatable glaucomatous defects. For example, clusters with more than six points at the p<5% level, more than four at p<2%, or more than two at p<0.5% had a high likelihood of being confirmed on subsequent testing. Volume, which accounts for both the number and severity of abnormal points, showed a particularly strong predictive value. Both cluster size and volume achieved an area under the curve (AUC) of 0.80 in predicting repeatable defects. Including information about the cluster’s location, specifically whether it lay in the central or peripheral rim of the VF, further improved predictive performance.

These findings may help clinicians identify which early VF defects are more likely to represent true glaucomatous loss. Recognising that larger and deeper clusters are more likely to be repeatable could lead to more focused monitoring, better prioritisation of follow-up testing, and more timely treatment decisions, ultimately improving the efficiency and accuracy of glaucoma care.

References:

1. Tan JCK, Phu J, Bell K, et al. Prediction of repeatable glaucomatous visual field defects based on cluster characteristics. Br J Ophthalmol. 2025; Published Online First: 03 July 2025.
2. Tan NYQ, Tham Y-C, Koh V, et al. The Effect of Testing Reliability on Visual Field Sensitivity in Normal Eyes: The Singapore Chinese Eye Study. Ophthalmology. 2018;125:15–21.
3. Boeglin RJ, Caprioli J, Zulauf M. Long-term fluctuation of the visual field in glaucoma. Am J Ophthalmol. 1992;113:396–400.

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Citation: New study identifies cluster characteristics that predict repeatable visual field defects in early glaucoma. touchOPHTHALMOLOGY.com. 15 July 2025.