Structure-Function Relationship in Glaucoma Patients With Parafoveal Versus Peripheral Nasal Scotoma

We evaluated whether the structure-function relationship in glaucoma patients with parafoveal scotoma or peripheral scotoma differs with the use of frequency doubling technology (FDT) or short-wavelength automated perimetry (SWAP) compared to standard automated perimetry (SAP).

Glaucoma patients with isolated parafoveal scotoma (PFS) within the central 10° of fixation in 1 hemifield and those with an isolated peripheral nasal step (PNS) within the nasal periphery outside 10° of fixation in one hemifield were studied. Peripapillary retinal nerve fiber layer (RNFL) thickness was measured using spectral-domain optical coherence tomography. The topographic relationships between structure and function were investigated.

In the PNS group, superotemporal (r(2) = 0.300, P = 0.001) and inferotemporal (r(2) = 0.302, P = 0.001) RNFL thickness showed significant correlations with the corresponding visual field (VF) sensitivity using linear regression model in SAP. In the PFS group, temporal RNFL thickness was not correlated with nasal mean sensitivity (MS) on SAP (r(2) = 0.103, P = 0.065). Using FDT, however, the temporal RNFL thickness was correlated with nasal MS in the PFS group (r(2) = 0.277, P = 0.001). Using SWAP, the temporal RNFL thickness was not significantly associated with regional VF sensitivity in the PFS group (r(2) = 0.052, P = 0.192).

In glaucoma with peripheral scotoma, the RNFL thickness was associated significantly with the corresponding VF loss in SAP, FDT, and SWAP. In eyes with PFS, however, the topographic structure-function relationships were not distinct with SAP or SWAP. Frequency doubling technology performed well in terms of structure-function correlation in glaucoma with PFS.