Why are males with compressive optic neuropathy predisposed to developing cranial nerve palsy and binocular vision problems?

Background: The aim of this study was to investigate the prevalence and characteristics of diplopia and cranial nerve palsies in a group of consecutive patients presenting with suspected compressive optic neuropathy. Methods: Fifty patients aged 17 to 93 years diagnosed with a brain tumour and possible compressive optic neuropathy were referred to an outpatient orthoptic clinic. The orthoptic investigation included an ocular motility assessment to determine the characteristics of the problems reported. All patients presented with a diagnosed brain tumour and possible compressive optic neuropathy. Results: Thirteen patients (26%) presented with complaints of diplopia pre-operatively and a cranial nerve palsy was found in 8 of these patients (61.5%) and all were male. This result was statistically significant (χ² =<0.001). Conclusion: The prevalence of cranial nerve palsy found in this cohort of participants was consistent with some of the literature. Interestingly only males with compressive optic neuropathy were affected with cranial nerve palsy. It was not possible, however, to identify a causal factor in this study.