High AC/A ET: Bifocals? Surgery? Or Nothing at All?

Abstract

IntroductionBifocals have been the standard of care for pure high AC/A esotropia for over 100 years, though surgery for the near esotropia is being offered more and more frequently. There has been no long term study comparing the effects of bifocals and surgery with a control group prescribed single vision lenses for the distance hyperopia.PurposeThis study compares the effects of these three treatment strategies on magnitude and control of the near angle, distance-near disparity, gradient AC/A ratio, binocular vision, and refractive error over a minimum follow-up interval of five years.MethodsPatients with “pure” accommodative esotropia with a high AC/A were given the option of surgery, bifocals, or single vision hyperopic lenses. All were followed a minimum of five years with sensorimotor exams and cycloplegic refraction.ResultsPatients managed with bifocals or single vision lenses experienced a 5Δ reduction in the near esotropia, with no corresponding decrease in gradient AC/A. Patients in the Bifocal Group were less likely to undergo emmetropization, and tended to an increase in the gradient AC/A with time. Surgery resulted in a significant reduction of the near angle and collapse of the distance-near disparity. The surgical reduction of the AC/A ratio was not permanent. More patients lost stereoacuity in the Surgery Group than in the other two Groups combined. Approximately one-third of patients in each of the three treatment groups achieved long-term success, though success was achieved at a significantly earlier age in the Surgery Group.ConclusionAny of the three treatments can be effective if used under the right circumstances, though each has unique benefits and the potential for undesirable sequelae.