Retinal segmented layers with strong aquaporin-4 expression suffered more injuries in neuromyelitis optica spectrum disorders compared with optic neuritis with aquaporin-4 antibody seronegativity detected by optical coherence tomography.

PURPOSE

To evaluate retinal segmented layer alterations in optic neuritis (ON) in an AQP4-Ab seropositive (AQP4-Ab+/ON) cohort and in neuromyelitis optica (NMO) with ON eyes (NMO-ON) compared with an AQP4-Ab seronegative ON (AQP4-Ab-/ON) cohort using optical coherence tomography (OCT).

METHODS

We recruited 109 patients with ON (161 eyes) and 47 healthy controls. All patients with ON were subdivided into three subcohorts: 37 patients (54 eyes) with AQP4-Ab+/ON, 45 patients (65 eyes) with AQP4-Ab-/ON and 27 patients (42 eyes) with NMO-ON. All subjects were evaluated for their peripapillary retinal nerve fibre layer (pRNFL) and inner macular segmented layer using OCT.

RESULTS

AQP4-Ab+/patients with ON had the same structural injury patterns as patients with NMO-ON, and the injury patterns were distinct from those of AQP4-Ab-/patients with ON. NMO-ON and AQP4-Ab+/ON preferentially damaged the pRNFL (all p=0.000), the macular retinal nerve fibre layer (mRNFL; p=0.000 and 0.032, respectively), and the inner plexiform layer (IPL; p=0.000 and 0.006, respectively) without differences in the retinal ganglion cell layer (p=0.106 and 0.374, respectively) compared with AQP4-Ab-/patients with ON. The thickness of the inner nuclear layer (INL) increased in NMO-ON (p=0.043) compared with that of AQP4-Ab-/ON without a significant difference in AQP4-Ab+/ON versus AQP4-Ab-/ON (p=0.353). When the thickness of the inferior nasal quadrant (NI) of the pRNFL was reduced to ≤46.5 μm (area under the curve 0.772, sensitivity 89.2% and specificity 57.5%) 6 months after ON onset, NMO was considered.

CONCLUSIONS

AQP4-Ab+/ON produced similar structural injury patterns as NMO-ON. The pRNFL, mRNFL and IPL in the two types of ON and the INL in NMO-ON suffered more damage than those in AQP4-Ab-/ON, which could be associated with strong aquaporin-4 expression. The thickness of the NI of the pRNFL could be a potential clue for predicting ON progression to definite NMO.