The retina is a layer of the eye that contains cells that allow us to see. At the time of the revelation of the Qur’an, this layer that made sight possible was unknown and the term retina was not in use. Yet the letters that comprise the word “retina” appear side by side in only one place in the Qur’an, in verse 8 of Surah Fatir. This verse also refers to “seeing,” for which reason there is a strong possibility that it refers to the retina. (Allah knows the truth.)
And what of him the evil of whose actions seem fine to him so that he sees them as good? Allah misguides whoever He wills and guides whoever He wills. So do not let yourself waste away out of regret for them. Allah knows what they do… (Surah Fatir, 8)
This verse, which contains the word “retina” that makes sight possible, refers to the Arabic verb “raa,” meaning “to see.” Verse 19 contains the sentence "The blind and seeing are not the same." Damage to the retina can lead to permanent blindness. Verse 20 refers to "nor are darkness and light." That term is highly significant in terms of the formation of the retina’s light-sensitive calls. All these terms regarding sight are very rare in the Qur’an. The fact that the word “retina” appears only in these verses out of thousands, is another of Allah’s miracles in the Qur’an.
taken from: http://www.miraclesofthequran.com/mathematical_12.html