Purpose
To investigate the ability of Ganglion Cell Complex (GCC) analysis with Optical Coherence Tomography (OCT) to detect an early axonal damage masked by optic disc edema in nonarteritic anterior ischemic optic neuropathy (NAION) and to find the relationship with visual field defect and visual function parameters.
Methods
24 patients participated in this retrospective observational study. RNFL, GCC average and minimum values, best corrected visual acuity (BCVA), Ishihara test and Humphrey visual field (24-2 SITA fast) were recorded at first month and six months after NAION. Pearson coefficient was used to find relationships between GCC and visual field defects.
Results
Mean RNFL decreased from 151,13 μ to 66 μ and GCC average and minimum from 68,21 μ and 56,08 μ to 56,76,09 μ and 43,18 μ respectively. At acute stage, atrophy of the optic nerve appeared in 8,3% of patients in RNFL; while 58,3% and 79% of patients exhibited an early damage on the GCC average and minimum. Atrophy increased to 87% at 6 months in RNFL and GCC average and minimum to 88% and 100% respectively. Pearson coefficients for correlation between GCC average at acute stage and Visual Field Index (VFI) and Mean Deviation (MD) at acute stage were 0,47 (p=0,047) and -0,46 (p=0,031). Stronger correlation was found between GCC at acute stage and VFI and MD at chronic stage; 0,54 (p=0,013) and -0,56 (p=0,01) respectively. Significant correlation was also found between total deviation of superior and inferior hemifields and its respective hemifields on the ganglion cell complex map; -0,48 (p=0,024) and -0,57 (p=0,006) for correlation between superior GCC at acute stage and inferior hemifield at acute and chronic stages respectively and -0,61 (p=0,002) and -0,59 (p=0,003) for inferior GCC at onset and superior hemifield at acute and chronic stages
Conclusions
GCC analysis with OCT is capable of detecting an early axonal damage in NAION eyes at the acute stage that cannot be detected by RNFL. GCC defect at acute stage shows significant correlation with global visual field and location of the defect, with a stonger correlation with final visual field defect.
Keywords: 612 neuro-ophthalmology: diagnosis •
613 neuro-ophthalmology: optic nerve •
627 optic disc