The relationship between preoperative and postoperative near stereoacuities and surgical outcomes in intermittent exotropia

Aims To classify patients with intermittent exotropia (IXT) according to the level of near stereopsis, evaluate postoperative stereoacuity and assess the surgical outcomes among groups. Methods The records of 137 patients with IXT were reviewed. Patients were divided into three groups based on the degree of stereopsis: good (40–60 arcsec), moderate (80–200 arcsec) and poor (>200 arcsec). These groups were compared with each other with respect to preoperative and postoperative clinical features. Results Poor stereopsis was found in 19 (13.9%) patients, moderate in 62 (45.2%) and good in 56 (40.9%) patients. There were no statistically significant differences among groups in the mean preoperative and postoperative exodeviations or in the rate of successful surgery. The preoperative and postoperative stereoscopic statuses were similar in each group. Patients with better stereopsis tended to be older when the IXT was first detected and showed better best-corrected visual acuity than those with poorer stereopsis (p=0.027, 0.005, respectively). Conclusions Classification of IXT based on the degree of near stereopsis offers a useful tool for the assessment of initial sensory status as well as postoperative prognosis. Also, a lower age at first detection of IXT and a lower best-corrected visual acuity were associated with poor near stereoacuity.