Diplopia can occur after strabismus surgery, occasionally in older children but more often in adults. Surgery can move the fixated image out of a suppression scotoma. In the several months following surgery, various responses are possible:
Fusion of the 2 images may occur.
A new suppression scotoma may form, corresponding to the new angle of alignment. If the initial strabismus was acquired before age 10 years, the ability to suppress is generally well developed.
Diplopia may persist.
Prolonged postoperative diplopia is uncommon. However, if strabismus was first acquired in adulthood, diplopia that was symptomatic before surgery is likely to persist unless comitant alignment and fusion are regained. Prisms that compensate for the deviation may be helpful during the preoperative evaluation to assess the fusion potential and the risk of bothersome postoperative diplopia.
A patient with unequal vision can often ignore the dimmer, more blurred image. Further treatment is indicated for patients whose symptomatic diplopia persists after surgery, especially if it is severe and present in the primary position. If vision in the eyes is equal or nearly so, temporary or permanent prisms should be tried to address any residual diplopia. If this approach fails, additional surgery or botulinum toxin injection may be considered. In some cases, intractable diplopia can be controlled only by occluding or blurring the less-preferred eye with a MIN lens (Fresnel, Bloomington, MN), Bangerter foil (Ryser, St Gallen, Switzerland), or Scotch Magic Tape (3M, St Paul, MN).
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.