It has been narrated from Prophet Muhammad (S.A.W) that "Eat and give each other quinces, because this fruit shines your eyes and makes friendship grow at your hearts." And his holiness has also expressed that "Eating quince eliminates the mist (darkness) of the eye". And it was stated by his Holiness somewhere else that "three things strengthen the eyesight: dragging Surmah (eyeliner), looking at green scenery and also looking at a beautiful face". His holiness also has stated that "Washing hands before eating food wipes poverty and after eating washes away sorrow and pain and brightens the eyes".
Moreover it has been narrated from Imam Kazim (A.S.) that, “If hair gets long, eyesight weakens and its light fades away. But hair cut will polish eyesight and lighten up the eye”. The holy imam has also stated elsewhere that,
"Three things will shine the eye: looking at grass, looking at water, and looking at a beautiful face".
In this respect, in some other sources Prophet Muhammad (S.A.W) has mentioned another thing that improves eyesight:"He who has read Quran while looking at it, will be benefitted by a good eyesight (his eyesight will improve) and Imam Ali (A.S.) has also stated that, "If some of you has an eye problem, they should read Ayat al-Korsi and asks for healing in their heart, because he will be cured by God’s will".
Imam Sadiq (A.S) has also addressed Mofazzal ibn al-Omar and said,
"Ponder upon the color of sky and the truth behind it. This color is the most compatible color with the eye and improves the eyesight".
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Hindi, Kanz al-Ammal, Vol. 10:51
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Sheikh Sadooq, Khasal, 92
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Muhammad Rey Shari, Encyclopedia of Medical Hadiths, Vol. 1:297