Hi,
For Rigid GP CL, correction of Corneal Astigmatism is not necessary because its curve automatically corrects the corneal astigmatism. In case of Soft CLs, correction of Astigmatism may be recommended (Toric CLs), if the cylindrical error is more than 1/4 of spherical error. So, in your case, astigmatic error may be safely ignored.
And as the CL prescription is slightly different from Spectacle prescription, in your case -7.0 D soft CL may be good and acceptable.
In case of any inconvenience, contact your optician or Ophthalmologist.
Next Steps
Ignore Astigmatism and get Soft CLs with power adjusted.
Health Tips
Take all precautions as advised for CL.