eye injection

I have received injections in my left eye for 2 years with just feeling pressure. Just received first injection in right eye. Betadine swab burned in right eye but never in left eye. Felt like the needle had a hard time entering eye and the pain was horrific but not so in left eye. Right eye stayed sore for 2 weeks where as left eye is sore for only a couple of days. Can anyone tell me why this happens?