The eye:

The cornea in the eye is completely transparent, but why?

The cornea is nourished by a fluid:

The cornea of the eye, which is an extremely transparent layer, has special properties that distinguish it from all other human cells concerning the way it is nourished. Had it been nourished as other cells, through the vessels, we would have seen things in a net. 

In fact, the cells allow nourishing fluid from inside the eye (aqueous humor) to leak into the cornea. After the corneal cells have been nourished, the cells pump the fluid out of the cornea.  Due to this way of nourishing, we are able to see things crystal clear.

Dear brothers, Allah the Almighty has provided the eye with an anti-freezing substance.  

The retina and the light photoreceptors: 

The human retina has an area of 1.094 square mm.

Unlike the most advanced digital camera which contains in each square mm 10.000 light photoreceptors, the retina contains one million light photoreceptors in each square mm, making us see clearly.

Moreover, the human eye can distinguish between 8 million colors. Better yet, the healthy eye can distinguish between the 800.000 shades of each color if they are displayed before it. Allah the Almighty says: 

(The Work of Allah, Who perfected all things)

[An-Naml: 88]

In another Surah, Allah the Almighty says:

(Were they created by nothing, or were they themselves the creators?)

[At-Tur: 35]