By Sarah Guy, MedWire Reporter
One-third of pediatric patients treated surgically for intermittent exotropia (eyes that turn outwards) have excellent post-treatment alignment, and two-thirds have satisfactory control of the condition after the procedure, show UK study results.
However, persistent overcorrection of the condition - defined as the presence of any manifest esotropia (eyes turning inwards) at the 1, 3, or 6 month follow up - was observed in 15% of the study cohort, and together with the 36% rate of poor post-treatment alignment are "of concern" say the researchers.
"A problem for practitioners is the lack of consensus regarding how and when to treat exotropia, and what constitutes a good outcome," write Deborah Buck (Newcastle University, Newcastle Upon Tyne) and colleagues in the British Journal of Ophthalmology.
The unknown natural course of childhood exotropia means "surgery will continue to be offered by clinicians and requested by parents, and although the chances of a good result are reasonable, the causes or causes of over-correction remain unclear," they add.
Of 72 previously untreated exotropia patients aged under 12 years who underwent surgery, 36%, 28%, and 36% had excellent, fair, and poor postoperative motor outcomes, defined according to a lack of or presence of esotropia, and stability of stereoacuity.
There was no significant difference in these results when sensory in addition to motor criteria were used, report the researchers.
Control of exotropia was measured using the Newcastle Control Score (NCS), and while 65% of patients achieved satisfactory control after surgery - defined as a total NCS of 2 or less or an improvement of at least 3 score points at final outcome - exotropia remained or recurred in 20% of the cohort.
The remainder (15%) was overcorrected, note Buck et al, and 40% remained so at the final postoperative assessment (maximum 12 months). Indeed, two participants may have developed amblyopia (lazy eye) as a result of overcorrection, and 16% of the overall cohort underwent subsequent botulinum toxin injections or a second operation for over- or under-correction.
"We believe any future studies should incorporate sensory and control outcomes alongside the more customary motor criteria as benchmarks for success, and we encourage clinicians to take into account patient/parental opinion regarding what constitutes a desirable outcome," the researchers conclude.
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