Contact lenses prior to assessment
If you wear contact lenses, these can distort the shape of the cornea and produce inaccurate measurements of the eye. When you stop wearing your lenses the eye gradually returns to normal.
If you wear hard or gas-permeable contact lenses, you will need to leave them out for four weeks before I can take accurate measurements. For soft lenses you will need to leave them out for two weeks. You may find that your vision fluctuates initially after removing your lenses as the corneal shape returns to normal.