Why are my eyes yellow?

The whites on my both my eyes (on the side closest to my nose) has been yellow for about 3 years now. I have tested negative to Jaundice and have perfectly normal liver and kindney function. I have been to two different eye specialists and they have no idea what it is. At one stage they thought I had pterygiums but this was also proven not the be the case. Can anyone please help me? this does affect me alot, as it looks unhealthy and people comment all the time.