Purpose: To determine the relationship between the sighting eye choice and functional and structural asymmetries in open-angle glaucoma (OAG).
Methods: Two hundred patients with bilateral OAG underwent dominant eye testing using a hole-in-a-card test. The paired eyes were divided into worse and better eyes according to the mean deviation (MD) of visual field (VF) results. Based on the results, patients whose sighting eyes corresponded to eyes with a better VF were designated as group 1, and those whose sighting eyes corresponded to eyes with a worse VF as group 2.
Results: The sighting eye corresponded predominantly to eyes with better VFs (P < 0.001). The MD of the worse eye was significantly lower (P = 0.008), and the intereye difference in MD was significantly larger in group 1 than in group 2 (P < 0.001). In a comparison of regional VF threshold values and corresponding retinal nerve fiber layer thickness (RNFLT), the superior and inferior VF threshold values were consistently more deteriorated in the nonsighting worse eyes in group 1 (P = 0.009 and 0.003), compared with the sighting worse eyes in group 2, whereas the corresponding RNFLT was not significantly different between the groups. Multiple linear regression analysis showed that the sighting eye choice (P = 0.047), higher vertical cup-to disc ratio (P = 0.042), older age (P = 0.044), thinner average RNFLT (P = 0.007), and average ganglion cell-inner plexiform layer thickness of worse eyes (P < 0.001) were significantly associated with the MD of the worse eyes.
Conclusions: The sighting eye choice was associated with functional asymmetry between eyes with glaucoma. The functional deterioration was evident in nonsighting eyes with worse VFs.