Characteristics of optic disc morphology in glaucoma patients with parafoveal scotoma compared to peripheral scotoma

We investigated the amount and location of optic nerve head (ONH) abnormal points and the retinal nerve fiber layer (RNFL) thickness with paracentral scotoma compared to peripheral scotoma.

Totals of 35 normal tension glaucoma (NTG) patients with isolated parafoveal scotoma (PFS) within a 10° radius in one hemifield, and 35 patients with isolated peripheral nasal step (PNS) within the nasal periphery outside 10° of fixation in one hemifield were enrolled if their mean deviation was greater than -10 decibels (dB). Global and sector optic disc stereometric parameters obtained by Heidelberg retina tomography and analyzed by Moorfields regression analysis (MRA), and retinal RNFL thickness measured using Cirrus spectral domain-optical coherence tomography were compared between the two groups. The percentages of superior and inferior field defects were evaluated.

In PFS, superior field defects (82.9%) were found to be dominant, whereas PNS showed a predominance of inferior field defects (80.0%). The PFS group revealed smaller rim area, more glaucomatous cup shape than the PNS group (P = 0.036, 0.012, respectively). In MRA classification, the percentage outside of normal limits (ONL) was greater in the PFS group (P = 0.006). Compared to the PNS group, the PFS group exhibited more glaucomatous ONH morphology in the temporal and inferotemporal sectors in a sector analysis of optic disc parameters, and had thinner RNFLs in the inferior quadrant, and at 7 and 8 o'clock (P = 0.007, 0.003, 0.005, respectively).

In early NTG, paracentral scotoma may be more significant than peripheral scotoma because of narrower optic disc rim and larger cup, especially inferotemporally.