Ans. d. Functional vision loss (Ref Kanski 6/e p 477, 790, 792-793)The most likely diagnosis in this young lady who presents with sudden severe bilateral loss of vision, more so on the right side, with no perception of light and normal examination findings including pupillary reflexes, fundus and optokinetic nystagmus, who is able to touch tips of her finger with right eye closed but not with left eye closed, is functional vision loss.