وَالْبَصَرُ وَهِيَ قُوَّةٌ مُودَعَةٌ فِي الْعَصَبَتَيْنِ الْمُجَوَّفَتَيْنِ
Sight is described as a faculty associated with two hollow nerves.
The classical anatomical explanation speaks of nerves connected with the eyes and brain. It should be read as a historical physiological account, not assumed to be a complete modern description of visual anatomy.
The chief epistemic point is that sight apprehends visible qualities such as color, light and shape. The eye is its ordinary bodily instrument.
Seeing the written letters of a sentence and understanding its meaning are distinct processes. Visual presentation supplies information that may require additional interpretation.