Station six
(allowed 5 minutes)
Following bilateral cataract operation, a patient has a post-operative refraction as follow:
OD  -4.00DS     6/6    Add +2.50 DS     N5
OS   -0.50DS     6/6    Add +2.50 DS     N5
She does not appear to be troubled by aneisokonia. However, when reading through her new executive bifocal glasses, she complains of vertical diplopia.

a. Examination reveals that she reads 0.6 cm below the optical centre of the
    reading section. What is the induced prism in the reading positions?

b. Suggest ways of reducing this prismatic effects.




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