Is it dangerous to rub closed eyes?
The answer is both yes and no, depending on how often and how hard one rubs his or her own eyes.

Occasional light rubbing is not a problem-- it stimulates tear production and relieves stress by lowering heart rate via the oculocardiac reflex. 

Frequent hard rubbing is a problem-- it can worsen eyesight in people who already have progressive myopia, and worst-case-scenario lead to retinal detachment. For those with glaucoma, can interrupt blood flow and even cause nerve damage. It can (but rarely) scratch, tear, or deform the cornea leading to pain and distorted vision. It can lead to damage of small delicate vessels, causing a subconjunctival hemorrhage, which is benign despite its worrisome appearance. 

It is generally recommended to just avoiding rubbing the eyes altogether! 

References:


www.abc.net.au/health/talkinghealth/factbuster/stories/2012/09/18/3592456.htm
http://www.visioneyeinstitute.com.au/dangers-rubbing-eyes/