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

Objective: 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.

Methods: 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.

Results: 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).

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