<prompt> What will be the prescription for spectacles in a patient having simple myopic with the rule astigmatism?-0.5D at 180 degrees0.5D at 180 degrees-3.0D at 90 degrees2.0D at 90 degrees  <response>: -0.5D at 180 degrees With the rule astigmatism - two principal meridian are at right angles with the veical meridian being more curved. Correction requires convex cylinder at 90 degrees or concave - cylinder at 180 degrees. Myopic astigmatism means the patient has to be given a concave cylindrical lens. Against the rule astigmatism corrected by convex C at 180 degrees or concave - C at 90 degrees Option 4 2.0D at 90 degrees is also with the rule astigmatism but this patient will have simple hyperopic with the rule astigmatism not simple myopic as expected from the question 