AIM: To study the correlation between retinal nerve fiber layer(RNFL)thickness changes and long-term visual function in Leber hereditary optic neuropathy(LHON)patients with 11778 mutations, and evaluate the role of early RNFL thickness in predicting long-term visual function.

METHODS: A retrospective analysis with 44 eyes from 23 LHON patients who were diagnosed with 11778 G>A/ND4 mutations by mt-DNA sequencing were included. The patients were divided into two groups based on whether BCVA is above LogMAR 0.5(equivalent to 0.3 decimal,WHO Low Vision standard)or not at 30mo follow up. Then, when the RNFL data of the two groups of patients at each predetermined time point(course of disease)were obtained, the candidate cutoffs of RNFL thickness were obtained by comparing the mean RNFL thicknesses of the two groups. Based on the obtained candidate cutoff values, the eyes with different RNFL values were divided into two groups for statistical analysis to determine whether the cutoff values can be used to predict prognosis of BCVA and visual field. Finally, the earliest cutoff value of RNFL thickness that can predict both BCVA and visual field is the target value.

RESULTS: According to the distribution of mean RNFL values in the eyes of patients with different BCVA groups, the candidate cut-off values of RNFL were determined as: 130μm after 2mo, 100μm after 4mo, 80μm after 8mo, and 65μm after 12mo from onset. Further analysis revealed that the RNFL value exceeds 80μm of 8mo after onset can be a better cutoff value to distinguishes the long-term vision, and which can predict both MD and MS of visual field with good distinction(all P<0.05). It was found that the long-term BCVA of 100% of the eyes with RNFL values less than 80μm after 8 months from onset was lower than LogMAR 0.5(equivalent to 0.3 decimal); while for eyes with RNFL thickness higher than 80μm after 8mo from onset, 31% of patients had vision greater than LogMAR 0.1(equivalent to 0.8 decimal), and only 34% of patients had long-term prognosis of low vision. In addition, the BCVA, MD and MS of visual field of the eyes with RNFL value exceeded 80μm were significantly better than those with eyes with RNFL less than 80μm.

CONCLUSION: In this study, whether the RNFL value exceeded 80μm after 8mo from onset can be used as the best predictive cut-off value for judging long-term BCVA and visual field.