i saw somewhere on internet the statement that the electrolysis can damage the skin collagen…is it true? does someone noticed the changes in the skin texture after electrolysis? 
Repeated overtreatment by incompetent electrolysis technique or faulty equipment can cause damage to the underlying skin (collagen and elastin). The key is to analyze this early on and make adjustments.
After any routine electrolysis proceedure, there will be minor inflammation and swelling that should disappear anywhere from 30 minutes to a week depending on your special healing powers.
If it takes more than a week for the area to heal, I would tell the electrologist so she/he could make adjustments with their technique or equipment settings. If she/he is defensive, it’s time to say adios.
Also, skin damage can occur if hairs are treated too close together. I scatter my work every third or fourth hair, especially when doing work on the face.
Damage to the underlying structures of the skin does not and should not happen when special care and above all KNOWLEDGE is heeded by the electrologist and if the client follows recommended aftercare instructions. It’s good that you ask questions and understand these things if you are considering electrolysis.
I would suspect that more people damage their collagen and elastin structure by smoking and sun worshiping, than by having electrolysis.