Brown ring around cornea. Brownish ring?

I have high myopic prescription. - 9 on both eyes. Astigmatism with cylindrical power of 0.75 and 1.25. Been wearing Toric silicon hydrogel soft contact lenses for a week. It is mostly comfortable only, no irritations, redness or excessive tears. Sometimes I don't feel the lens at all in eyes. But Im noticing a slight brownish ring around cornea (around black area). I dunno whether it's because of contact lens or Im having this even before wearing contact lenses and now only started noticing as I'm seeing my eyes often. Little bit worried. Kindly suggest what it could be.. Contact lens if bigger than cornea, if touches the white part can cause this brownish ring? My cornea too small for std contact lens dia..?