Surgery versus Active Monitoring in Intermittent Exotropia (SamExo): study protocol for a pilot randomised controlled trial

Abstract

BackgroundChildhood intermittent exotropia [X(T)] is a type of strabismus (squint) in which one eye deviates outward at times, usually when the child is tired. It may progress to a permanent squint, loss of stereovision and/or amblyopia (reduced vision). Treatment options for X(T) include eye patches, glasses, surgery and active monitoring. There is no consensus regarding how this condition should be managed, and even when surgery is the preferred option clinicians disagree as to the optimal timing. Reports on the natural history of X(T) are limited, and there is no randomised controlled trial (RCT) evidence on the effectiveness or efficiency of surgery compared with active monitoring. The SamExo (Surgery versus Active Monitoring in Intermittent Exotropia) pilot study has been designed to test the feasibility of such a trial in the UK.MethodsDesign: an external pilot patient randomised controlled trial.Setting: four UK secondary ophthalmology care facilities at Newcastle NHS Hospitals Foundation Trust, Sunderland Eye Infirmary, Moorfields Eye Hospital and York NHS Trust.Participants: children aged between 6 months and 16 years referred with suspected and subsequently diagnosed X(T). Recruitment target is a total of 144 children over a 9-month period, with 120 retained by 9-month outcome visit.Randomisation: permuted blocks stratified by collaborating centre, age and severity of X(T).Interventions: initial clinical assessment; randomisation (eye muscle surgery or active monitoring); 3-, 6- and 9-month (primary outcome) clinical assessments; participant/proxy completed questionnaire covering time and travel costs, health services use and quality of life (Intermittent Exotropia Questionnaire); qualitative interviews with parents to establish reasons for agreeing or declining participation in the pilot trial.Outcomes: recruitment and retention rates; nature and extent of participation bias; nature and extent of biases arising from crossover or loss to follow-up; reasons for agreeing/declining participation; variability of cure rates (to inform power calculations for a definitive RCT); completion rates of outcome measures.DiscussionThe SamExo pilot trial will provide important pointers regarding the feasibility of a full RCT of immediate surgery versus deferred surgery/active monitoring. The results of this pilot, including differences in cure rates, will inform the design of a definitive RCT.Trial registrationISRCTN44114892

Development of a core outcome set for amblyopia, strabismus and ocular motility disorders: a review to identify outcome measures

“…In 12 studies alignment was measured using “prism alternate cover test PACT” [4, 5, 54, 58, 59, 63, 67, 70, 71, 74, 77, 78] and /or with “simultaneous prism cover test SPCT” in eight studies [4, 53, 63, 66, 74, 75, 77, 79]. “Cover test” was reported in five studies [2, 42, 73, 74, 79], “Synoptophore” in four [2, 4, 42, 53] and “Hirschberg test” in three [54, 73, 79].…”

“…Other adverse events specified in included studies were “globe perforation” [65, 70, 78], and “induced ptosis” post botulinum toxin injection [2, 53, 54].…”

“…Long-term change following surgical procedures including “recurrence of deviation” [68], “overcorrection” [4, 78] and “re-operation rate/number of operations needed” [53, 55, 65, 78] were reported.…”

“…This was assessed using different questionnaires that could be generic (for example SF-36) [61, 62], or specific to age (for example EYE-Q) [77, 78], specific to vision (for example VFQ-25) [58] or specific to condition (for example the IXTQ) [5, 50, 51, 62, 72, 77].…”

Intermittierende Exotropie

“…Diese Studie wird wertvolle Informationen zu Vor-und Nachteilen beider Operationen liefern. Zum anderen wurde kürzlich die Pilotphase der britischen SamExo-Studie ("Surgery versus Active Monitoring in Intermittent Exotropia") beendet [73]. In dieser randomisierten multizentrischen Studie werden "aktive Beobachtung" und chirurgische Therapie der IXT bei Kindern untersucht.…”