Use of dissimilar trifocals to equalize fields of view for asymmetric orbital positions secondary to progressive facial hemiatrophy.

A 58-year-old woman presented, complaining that the vertical field of view (henceforth referred to as "field") through the middle (intermediate distance) segment of her right trifocal lens was disturbingly narrower than the left. She had undergone facial surgery for Parry-Romberg syndrome, after which right enophthalmos and hypo-orbit persisted. The longer lens-to-eye distance in the enophthalmic right eye caused the 7-mm vertical dimension of the middle segment to subtend a smaller angle at the right eye than the left, producing unequal fields. Trifocals with a larger 10-mm right eye intermediate segment vertical dimension and unchanged 7-mm left eye dimension made the angular fields through the segments nearly equal. Trifocal segments of unequal vertical dimensions were an effective solution to unequal fields of view secondary to monocular enophthalmos.