Esotropia with a high accommodative convergence-toaccommodation (AC/A) ratio is a relatively common type of strabismus in children. Typically, it presents in early childhood as esotropia greater at near than distance fixation; however, not all of these cases are considered high AC/A. If the near deviation reduces significantly when the child looks through þ3.00-diopter (D) lenses, then the deviation is established as accommodative rather than the result of an excess of convergence driven by near proximity. The AC/A ratio can be measured using the gradient method or the heterophoria method. Using a þ3.00-D lens at near fixation, the AC/A ratio by the gradient method is simply the difference in prism diopters of esotropia with versus without the lens, divided by 3 D (lens power). An AC/A ratio of more than 5 is abnormally high. The traditional treatment of high AC/A esotropia has been bifocals, which reduce the accommodative demand at near fixation and reduce or eliminate the esotropia. However, other treatments have included single-vision lenses, pharmacologic therapy, and extraocular muscle surgery. Long-acting cholinesterase inhibitors such as echothiophate iodide act directly on the ciliary body to facilitate accommodation. Surgical approaches have included bilateral medial rectus recessions with or without posterior fixation sutures, and some investigators have reported outstanding surgical results. In one study, surgery eliminated the need for bifocals in 22 of 23 children with high AC/A esotropia. Compared with single-vision lenses, bifocals seem to have the advantage of allowing a child to spend more time with excellent near alignment. Many children with bifocals demonstrate excellent near alignment and stereopsis in the office setting. In fact, many children will lift their chins to maintain fixation through the bifocal on a near target, strongly suggesting that they are deriving visual benefit from wearing a bifocal. Proponents of bifocals point out that, if a child spends more time with excellent alignment, it is likely that he or she will develop better binocularity and stereopsis. Intuitively, this makes sense. However, there are many examples of treatments that intuitively seem beneficial, but did not show any advantage when tested versus another treatment or placebo in a properly conducted randomized clinical trial. Despite the theoretical advantages, there are many disadvantages to wearing bifocals for high AC/A esotropia. They are more expensive than single-vision lenses, and it can be difficult for some children to accept and wear bifocals. For school-aged children, there is the social stigma of not only wearing glasses, but also of wearing glasses that look very different. Although progressive lenses without a line are an option, it can be more difficult for young children