Eyelid cyst can be caused by several factors and they also have several types. It is not as serious as you imagine, but you still can't ignore this problem. Basically,the factors are chronic Blepharitis,out-of-date cosmetics, leaving make-up on overnight,staph bacteria,eye duct blockage,poor hygiene and dirty contacts.The best way for treating eyelid cyst is to improve personal hygiene.Tell your grandpa not to touch or rub his eyes at all.You have to know that bacteria can go into a person's eyes quite easily.Prepare your grandpa a personal towel and eye drops,don't let him share with anyone.However,if your grandpa feels too much pain in his eyes,you should send him to the doctor right away.May God bless you and your grandpa!