John 9 1-22
typhlon τυφλὸν blind Adj-AMS
1537 [e] ek ἐκ from Prep
1079 [e] genetēs γενετῆς. birth.
6When he had thus spoken, he spat on the ground, and made clay of the spittle, and anointed his eyes with the clay, 7and said unto him, Go, wash in the pool of Siloam (which is by interpretation, Sent). He went away therefore, and washed, and came seeing.
(below is the Greek)
This passage in John 9:1 is unique, in that it is apparently the only place 'blind from birth' appears in the NT., according to Meyer's Commentary. (Bible Hub)
The Greek rendering of the text did not seem to reveal any clues that might fit with what you were asking, clues to the nature of the man's blindness.
However, there is something available in the Greek and English text, that might be otherwise overlooked, if not highlighted, in order to have another look.
What Jesus did to the blind man, by spitting on the earth, and with his spittle, creating clay, with which he touched the eyes of the man, - this is reminiscent of the original creation of man, by God.
In Genesis we have God 'creating Adam from the dust of the earth', and forming him from it.
From this visual picture that Jesus gave us, we could assume that this healing of congenital blindness might fall into the category of 'creative miracle', imitating God's own handiwork on Adam, and from this we might assume then, that the man born blind was born without actual eyes, because it appears from the text that Jesus may have built him a pair, by what he did with his Divine saliva, mixing it with clay. (like in the beginning, 'Adam was made from the earth')
In this case, the man's eyeballs may have begun to be created, right there in the Divine spittle and dust. Jesus 'sent' him to the pool called 'sent', to wash, which would have to be an act of faith on the blind man's part, him setting out all muddy, eager to fulfill Jesus' request.
The act of washing in water suggests baptism, repentance from sin, coming up out of the water, cleansed, and in this man's case, physically seeing. Later in the story, Jesus revisits him in such a way as to give him spiritual sight as well, because the man says that he believes on Jesus.