Is Kohl Beneficial To The Eyes?
Question

Did Prophet Muhammed (saw) apply surma (kohl) to his eyes? And are there any Hadiths that narrate this? In the USA kohl is banned as it causes lead poisoning (as they say). Can this be true? because I would like to apply it as well, as I suffer from poor vision.
Praise be to Allah.In a number of Hadiths it is narrated that the Prophet (peace and blessings of Allah be upon him) used kohl and commanded others to do so. For example it is narrated in the Musannaf of Ibn Abu Shaybah (may Allah have mercy on him), from the Hadith of Anas (may Allah be pleased with him), that the Prophet (peace and blessings of Allah be upon him) used to apply kohl to his right eye three times, and to his left eye twice. This Hadith was classed as authentic by Al-Albani in As-Silsilah As-Sahihah no. 633. And it was proven in Sunan An-Nasa’i (5113) and Sunan Abu Dawud (3837) and elsewhere, from the Hadith of Ibn `Abbas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: “The best of your kohl is ithmid (antimony), for it makes the vision clear and makes the hair  grow.” 
Ibn Al-Qayyim (may Allah have mercy on him) said: “Kohl protects the health of the eyes and gives strength and clarity of vision, and cleanses the eye of bad substances. In addition to that some types of kohl also serve as an adornment and if it is applied before going to bed this is even better, and ithmid is more efficacious than other types of kohl.” (Zad Al-Ma`ad, 4/281) 
It says in Al-Mughni: “It is recommended to use kohl an odd number of times.” (Al-Mughni, 1/106)
It says in Al-Majmu`: “With regard to using kohl an odd number of times, there is a difference of scholarly opinion. It was said that it should be applied an odd number of times to one eye and an even number of times to the other, so that the total number will be odd. The correct view of the scholars who examined this issue is that it should be applied an odd number of times to each eye. Based on this, the Sunnah is to apply it three times to each eye.” (Al-Majmu` 1/334) 
Shaykh Ibn `Uthyamin (may Allah have mercy on him) was asked: Some eye doctors say that kohl is harmful to the eyes and they advise not using it. What do you say to them? 
He replied: 
“Ithmid (antimony) is known to be very good for the eyes. I do not know anything about other types of kohl. Trustworthy doctors are the ones whom we should consult on this matter. 
It was said of Zarqa’ Al-Yamamah, who could see as far as three days, that when she was killed, they saw that all the veins of her eyes bore traces of this ithmid.” (Majmu` Al-Fatawa, vol. 17; Chapter on medical treatment and visiting the sick) 
From the above it is known that kohl is good and is not harmful to the eyes, rather it is beneficial. But there may be some kinds of modern, manufactured kohl that contain some chemical ingredients which may cause physical damage and remove some of the benefits of kohl. Hence people nowadays should look for pure kohl and not regard every kind of kohl available nowadays as beneficial.
For more details, please refer to the following answers: 67897 , 34552 , 103345 , 32556 , 118089 , 22922 , and 144957 .
And Allah knows best.