Stability of near stereoacuity in childhood intermittent exotropia

Abstract

Purpose To investigate the course of near stereoacuity in a cohort of children with untreated intermittent exotropia. Methods A total of 95 children aged 2 to 16 years with untreated intermittent exotropia were identified who had measurements of near stereoacuity, using the Preschool Randot (PSR) test on at least two successive examinations, with no intervening treatment. Deterioration was defined as a drop of at least 3 octaves, based on test–retest data. Alternative secondary analyses were performed defining deterioration as a drop of at least 2 octaves or as a transition from normal to subnormal. The main outcome measure was the deterioration rate calculated at 1 and 2 years using a Kaplan-Meier survival analysis. Results For near stereoacuity, the rate of decreasing 3 or more octaves was 2% (95% CI, 0%-6%) at 1 year and 7% (95% CI, 0%-16%) at 2 years. The alternative secondary analyses revealed similar low deterioration rates. In most cases of apparent deterioration, near stereoacuity returned to baseline levels without treatment. Conclusions For children with untreated intermittent exotropia, deterioration in near stereoacuity at 1 and 2 years is infrequent. Therefore, performing surgery for intermittent exotropia to proactively prevent deterioration of near stereoacuity cannot be justified. Retesting stereoacuity is critical to determine whether any measured decrease in stereoacuity is real.

Improvement in Fusion and Stereopsis Following Surgery for Intermittent Exotropia

“…Pratt-Johnson et al 18 and Aborms et al 19 believed that early surgery should be performed to preserve stereoacuity. They suggested surgical invention at younger than 4 and 7 years, respectively, whereas Holmes et al 12 proposed that one advantage of delaying or avoiding surgery for intermittent exotropia in younger children is avoidance of prolonged consecutive esotropia, with possible risk of permanent loss of stereoacuity. Others proposed that the surgery should be postponed because not all intermittent exotropias deteriorate and some will even resolve spontaneously after several years.…”

“…[7][8][9][10] Previous studies have proposed that patients with intermittent exotropia have good near stereoacuity and deteriorated distance stereoacu-ity, 2,11 whereas others 7,8 deemed that near stereoacuity was significantly poor in intermittent exotropia compared to normal patients preoperatively and postoperatively. Holmes et al 12 believed that near stereoacuity is stable and surgery cannot be considered as an effective way to restore near stereoacuity in intermittent exotro-Purpose: To evaluate fusion stereopsis in patients with intermittent exotropia before and after strabismus surgery.…”

Hyperopic refractive errors as a prognostic factor in intermittent exotropia surgery

“…Distance stereoacuity has been commonly used to monitor deterioration of IXT, because it is known to correlate better with the course of IXT than near stereoacuity. [35][36][37] However, Holmes et al 38 reported that monitoring near stereoacuity is reasonable in children with IXT, because the functional importance of near stereoacuity in children, as well as distant stereoacuity, has been clearly established, and younger children are more interested in near works and functional works such as pegboard task, water task, and bead task, which are related to near stereoacuity. 39 In our study, most patients were relatively young children, therefore improvement in near stereopsis is an important result.…”

Is intermittent exotropia a curable condition?

“…There are currently few data on the natural history of intermittent XT, but in a previous study of the course of stereoacuity in children with untreated intermittent XT, we found a very low deterioration rate over a 2-year period. 28 Further data on stereoacuity in the context of the natural history of intermittent XT, as well as following surgery, will be available at the completion of ongoing randomized clinical trials currently being conducted by the Pediatric Eye Disease Investigator Group (clinical trial identifiers: NCT01032330 and NCT01032603). We also need better methods of categorizing children with intermittent XT as having either monofixation or bifixation, and the new Pediatric Vision Scanner may prove useful in this endeavor.…”