Intervention for intermittent distance exotropia with overcorrecting minus lenses

Aim There are numerous treatment options for intermittent distance exotropia. The aim of this study is to evaluate the use of overcorrecting minus lenses as a primary treatment option for intermittent distance exotropia (IDEX) and determine ocular alignment status after 5 years from commencement of the study. Methods Prospective nonrandomised longitudinal cohort study in which 21 patients were recruited with a diagnosis of IDEX. Treatment was instigated with the minimum minus lens required to achieve control of the manifest deviation. The strength of lenses was reduced over time while monitoring the results of orthoptic measurements. The results were evaluated by nonparametric (Wilcoxon) and parametric (paired t-test) analysis. Results Thirteen female and eight male patients were recruited with a mean age of 5 years at the start of treatment. There was a significant reduction in angle of deviation after treatment. Overcorrecting lenses did not appear to induce myopia. Twenty-four per cent of the patients had a successful outcome, 28% had a good outcome, and 33% required surgery at a later date. Conclusions Fifty-two per cent of the patients achieved a successful or good outcome with overcorrecting minus lenses alone, and this was maintained for at least 1 year follow-up. Those requiring surgery had been unable to wean out of lenses but had a successful outcome after one procedure. We recommend overcorrecting minus lenses as a primary treatment option for IDEX with the knowledge that surgery, if subsequently required, is safely delayed to an older age without prior loss of binocular vision.