Methanol toxicity is relatively rare and comparatively little is known about its etiology. I found a correspondence published in the journal Nature in 2004, it seems to a good review of the literature, given that I could not find a recent review on the topic. Please take a look, especially at the sources that the following paragraph cites:
Methanol is particularly toxic to the optic nerve, leading to acute
blindness. Based on a histopathological study, the retrolaminar optic
nerve myelin sheath seems to be selectively vulnerable to methanol
poisoning due to its anatomical structure. In the acute phase, the
hyperaemia and swelling of the optic disc has a papilloedema-like
appearance. The axoplasmic flow stasis at the nerve head and
alteration of the myelin sheath in the retrolaminar nerve segment were
demonstrated in experiments using rhesus monkeys. The pathogenesis is
presumed to be histotoxic anoxia in a vascular watershed area, which
is the result of direct inhibition of cytochrome oxidase by formic
acid. Additionally, the increasing pressure following oedema in the
visual pathway might further aggravate the deterioration due to
ischaemic changes. Therefore, effective methods to treat the oedema
might be important, such as the use of intravenous steroids and
diuretics. The mechanism of subsequent optic atrophy in patients with
methanol poisoning is still unknown, it was suggested to be due to
progressive demyelination. The distinct glaucomatous-like cupping of
the optic disc suggests extensive loss of retina ganglion cells, which
has been thought to result from retrograde degeneration of optic nerve
axons.
It seems that in our best understanding, the optic-specificity of the action of methanol seems to be due to the nature of the myelin sheath that insulates the optic nerve.