Well, in my opinion, you should not use this kind of eye drops. Of course, by using it, it will help to whiten the white part in your eyes and clear the blood spots in eyes. But on the other hand, if you instill the drops again and again, it can just lead to some side effects. For example, it will just make your eye become more sensitive and in some degree, some eye diseases can occurs. In common, you will feel dry in your eyes. And your eyes will become redder then before. Also, blurred vision, and double vision can be possible too. So just stop using it.
You could use the whitening eye drops to whiten your eyes. However, it is not appropriate for everyone because of the different constitution of the body. Some people's eyes are so sensitive at the skin around the eyes. If you want to whiten your eyes, you'd better eat more vegetables, drink more water and sleep well to make the eyes be in the healthy state.
Yes, eye whitening is safe. Though it is safe for you to use, you should use it very sparingly. Collyre Bleu which is marketed in France and US is the most popular sclera-whitening drops. Moreover, you should not use the drops while wearing contact lenses or suffering from any eye problems and use 2 drops in each eye for 2 to 3 a day at most. Whitening drops are just constrict your blood vessels and they are not the solution of fixing the redness. If you use in a wrong way, it will cause redness, b/c and your vessels will become engorged and actually more red than them use to be.