Let me first of all preface it with a poem by William Blake:-
“To see a World in a Grain of Sand
And a Heaven in a Wild Flower,
Hold Infinity in the palm of your hand
And Eternity in an hour.”
The poem posted by OB however is about "seeing" the "cosmos", meaning Life, human existence, through one's own or another person's eyes, i.e. the eyes are both the arbitrative interpreter and a private "window" to a person's "soul" or innermost thoughts or emotions.
So, we have,
我傻楞着 -- I was stunned,
不知说的是你 -- not to mention for you as well,
那么要读懂这宇宙 -- that in order to understand this cosmos / universe,
就只须读懂一个人的眼睛 -- you needed to understand the eyes of a person,
该是什么样的眼睛 -- or rather what sort of eyes those are.
The poem is therefore about an epiphany, (a moment of sudden understanding or revelation, he was stunned?), that the "kind" of eyes a person has, (meaning whether they are judgmental or not, condescending, bias, etc,), would impact, affect how a person sees the cosmos, (i.e. life, human existence, etc,)
That is, life is how we see it with the sort of eyes we possess.
As in William Blake's poem, you may see a grain of sand, but the poet sees a World; a Wild Flower, he sees Heaven.
On another level, in OB's poem, there is also the banal interpretation. That is, the physical Universe is also subject to a personal interpretation, depending on what sort of eyes one has.
For some eyes, there is only the vast, infinite expanse of stars, planets, galaxies, wondrous as they are; but to other eyes, they see the creative splendor of a Supreme Being.