Well, it seems that you are quite interested in this particular field. So, as far as I know, it is helpful for our health if we cry from time to time. There are a lot of benefits for our eyes, because by crying, we will better relieve our grief and stay happy, and we could keep our eyeballs moist and healthy. Also, we could discharge some toxic things by crying, as well as some dirty stuff. Anyway, it is a good way of staying healthy.
Yes, it is true that crying actually good for eyes. There are many reasons for this saying.
The tears could enable us to see. Tears are the lubricant in our eyes, which could lubricate our eyeball and eye lid. It can also help avoid dehydration of our mucous membranes. I can't imagine without this lubricant in our eyes. Moving or truing eyeball could be very uncomfortable. Secondly, tears could kill bacteria in eyes, which are so called the antibacteria and antivirul agent in our body. Whenever we got something into our eyes, tears can run out to wash our eyes. It contains lysozym, which could kill 90-95% of bacteria in our eyes.
Thirdly, tears could remove the toxins which are generated with your distress or grief. It can also cheer mood. After a good crying, you can feel much better, less stress, and relaxed. Anyway, crying is very good for your eyes and your health.
It is true that appropriate crying will be good for your eyes because it will improve your excretion in the eyes. If you never cry during this time, your excretion system will not work in high state. After you cry a little, the bacterium in your eyes may be out. In a word, crying in the appropriate amount will be good for your eyes.