A team based out of the Schepens Eye Research Institute in Massachusetts recently demonstrated that strong pointwise and pattern-specific visual field (VF) symmetry exists between fellow eyes in patients with mild to moderate glaucoma. This means that VF defects in one eye strongly correlate with the same types of defects in the other eye, and VF patterns of the worse eye can be used as a reference to help interpret the VF loss in the better eye.

The study selected 24-2 VFs of both eyes of 63,604 multicenter patients tested on the same date with a mean deviation ≥-12dB. VFs were categorized as normal or by defect pattern (15 total). The inter-eye correlation of archetypal VF patterns was strongest for the same defect pattern between fellow eyes. A statistical measure for predicting defect patterns, called the area under the receiver operating characteristic curve (AUC), ranged from 0.69 (superior nasal step) to 0.92 (near total loss). The AUC for predicting superior paracentral loss was 0.89.

In descending order of statistical significance, superior paracentral loss in the better eye was positively correlated with coefficients of superior paracentral loss, central scotoma, superior altitudinal defect, nasal hemianopia and inferior paracentral loss in the worse eye. Likewise, loss in the better eye was negatively correlated with coefficients of the normal VF, superior peripheral defect, concentric peripheral defect and temporal wedge.

The researchers concluded that their findings provide valuable insight into the pathophysiology of glaucomatous optic nerve damage. “This implicates that systemic/inherited factors (e.g., gene and environment) have a greater impact on glaucoma than local, eye-specific factors (e.g., inter-eye variations of myopia severity and optic nerve head architecture),” they wrote in their paper. “Systemic factors would likely lead to bilateral or similar VF loss patterns in fellow eyes as opposed to local, eye-specific factors that would more likely produce unilateral or dissimilar VF loss patterns.”