DEC 17, 2012
Comprehensive Ophthalmology, Pediatric Ophth/Strabismus
This study examined surgical outcomes in intermittent exotropia and found that while excellent motor/sensory outcomes were achieved in one-third of patients and satisfactory control in two-thirds, 37 percent had poor outcomes and 15 percent had persistent over-correction. The authors note that surgical dose was similar in those under- and over-corrected, suggesting that over-corrections cannot be avoided merely by getting the dosage right. Additionally, initial over-correction did not improve the chance of a good outcome. Therefore, they recommend a randomized controlled trial in order to gain more information on this issue.
This article stuck out to me because the results of surgery for intermittent exotropia seem rather poor. Only 35 percent of patients had an "excellent" outcome (0-8 PD [prism diopter] intermittent exotropia at distance) and 28 percent had a "fair" outcome (≤ 4 PD esotropia). Poor outcomes were considered 9-15 PD intermittent exotropia at distance. However, results do not always mirror patient satisfaction. I agree that randomized clinical trials are needed since the results seem less than stellar at this time.
The study included results for 72 children younger than age 11 who underwent surgery at 18 centers in the United Kingdom. Mean follow-up was 21 months.
The authors found that preoperative and surgical characteristics did not influence primary outcome. Intermittent exotropia remained or recurred in 20 percent of patients. There was no relationship between over-correction and preoperative characteristics or surgical type.
Median angle improved by 12 PD at near and 19 PD at distance (P < 0.001). Median Newcastle Control Score improved by 5 (P < 0.001). The risk of developing amblyopia, losing stereoacuity, or deteriorating to constant exotropia after surgery was slight. However, 40 percent of those initially over-corrected remained so by last postoperative assessment and even a small initial overcorrection did not predict success.
The authors were unable to identify any particular causes of long-term over-correction as they found no relationship between this and any characteristics including age, surgery type or dose. Their data suggest that initial over-correction is not necessarily beneficial to longer-term outcome.
They recommend that any future studies incorporate sensory and control outcomes alongside the more customary motor criteria as benchmarks for success, and encourage clinicians to take into account patient and parental opinion regarding what constitutes a desirable outcome.