It's cruel to make fun of visually impaired people.

Literal

Eye [poss-の] not-free people [obj-を] make-fun-of [nom-の] [topic-は] cruel thing [copula-である].

目の不自由な人 ('people whose eyes are not free') is the polite Japanese way to say 'visually impaired.' ばかにする ('make a fool of') is a common colloquial verb. ~のは…ことである frames the nominalized action as the topic, then judges it.