Spherical equivalent is more than just the first number on your Prescription. You take half of the second number and add it to the first. For instance,
-8.00-2.00X180 The spherical equivalent of this prescription is -9.00. If you're just at around -9.50-1.00X180 that's -10.00. I've been working in Optometry and I haven't seen a prescription that high ever. Crazy.