A man who will wear a distance correction

R + 4.00D L + 4.00D needs 2 of base out prism each eye because of an esophoria. How much decentration and in which direction will required to supply this prism?

R + 4.00D L + 4.00D

How much decentration and in which direction will required to supply this prism?

Answer to question a The decentration is out by 5mm. Remember the formula P = dF P is the prism power = 2 d is decentration is cm = unknown F is the refracting power of the lens = 4 d is therefore 0.5 cm or 5 mm. Because the lens is plus and the patient is esophoric, the decentration is out