Successful Correction of Early Consecutive Exotropia with Over-Minus Spectacles

Consecutive exotropia develops in 4–27% of patients after surgical treatment of esotropia.[1] The deviation can manifest immediately after surgery due to surgical miscalculation or muscle slippage or months to years later due to stretched scars or fusion abnormalities resulting from various risk factors, including amblyopia. The standard treatment modality is surgical medial rectus advancement, but a repeat surgery is cumbersome. We report the utility of over-minus glasses in correcting early consecutive exotropia. An 18-month-old female child presented with a history of inward deviation of the left eye noted from six months. The child's fixation was central, steady, and maintained. Hirschberg's test revealed 15° left esotropia [Fig. 1a]. Alternating esotropia with cross fixation noted. Krimsky prism test showed 40 prism dioptres base out esotropia, and the rest ocular examination was normal. Cycloplegic refraction with 1% atropine eye ointment showed +2.00 DS/+0.5 DC ×90° in the right eye and +2.00 DS/+0.50 DC ×90° in the left eye. A diagnosis of essential infantile esotropia was made, and the child underwent surgical treatment with a bimedial rectus recession of 5.5 mm under general anesthesia after repeating the measurements on two separate occasions, one month apart. On postoperative day 1, the child developed 15° alternating consecutive exotropia [Fig. 1b]. No limitation of adduction or palpebral fissure widening on adduction, it was decided to give a trial of over-minus glasses with -2.00DS, and good compliance was ensured. On follow-up, over a few months, the child was orthotropic with the glasses. The spectacles were weaned, and the child continued to be orthotropic without glasses [Fig. 1c and d].Figure 1: (a) Clinical photograph of the child showing the presence of 15° left esotropia. (b) Clinical photograph depicting the presence of 15° exotropia following a bimedial recession. (c) Clinical photograph of the child being orthotropic with over-minus spectacles and (d) maintaining orthotropia after three months of weaning the over-minus spectaclesDiscussion Early-onset consecutive esotropia is due to muscle slippage intraoperatively or due to surgical overcorrections.[2] Surgical miscalculations can arise from variations in the anatomical insertions of the medial rectus or due to the difficulty in obtaining a precise measurement in a small child. It is essential to repeat the measurements on two occasions, at least prior to the surgery. Late exotropia is due to stretched scars or problems with binocular fusion.[3] The risk factors for developing consecutive exotropia are poor fusion or stereopsis, amblyopia, anisometropia, high hypermetropia with diminished accommodative convergence, large medial rectus recession, oblique muscle dysfunction, dissociate vertical dysfunction, and increased number of previous surgeries.[4] Management can be done in a combination of uni/bilateral medial rectus resections or medial rectus advancements, or uni/bilateral lateral rectus recessions. Furthermore, performing a repeat surgical correction is met with difficulties like repeat general anesthesia, anxiety in parents, lack of well-established surgical dose corrections, higher incidence of exodrifts weeks after surgery, and scarring from repeat surgeries. Over-minus spectacles are an effective nonsurgical alternative treatment for exodeviation. It induces accommodative convergence, which reduces the angle of exodeviation. The vergence response can be enough to permit the child to overcome exodeviation using large fusional convergence amplitudes, especially in the immediate postoperative period after a consecutive exotropia. So far, over-minus glasses have been reported in the management of intermittent exotropia as a conservative measure to postpone surgery.[5] Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.