Problems and pains always cause physical problems. Gradual and constant sorrow cause aging of the face and graying of the hair. As time passes and science advances, it becomes more evident that what problems sorrow and grief cause. It has been scientifically proven that the whiteness of people's eyes is caused by changes in the blood vessels of the eye for various reasons, including psychological and nervous disorders. Blood pressure increases due to sadness and grief, causing whiteness and blindness of the eyes. Most likely, you know Jacob, peace be upon him. His name is mentioned in the Torah, the Bible, and the Quran. But his name is mentioned in the Quran along with a scientific miracle and this medical matter is well explained:
Yūsuf
وَتَوَلَّىٰ عَنۡهُمۡ وَقَالَ يَٰٓأَسَفَىٰ عَلَىٰ يُوسُفَ وَٱبۡيَضَّتۡ عَيۡنَاهُ مِنَ ٱلۡحُزۡنِ فَهُوَ كَظِيمٞ (84)
He turned away from them and said, “O my sorrow for Joseph!” And his eyes turned white [*] because of suppressing his grief. 
[*] i.e., he lost his sight.​​​​​​​