Lateral Rectus Muscle and Anterior Segment Optical Coherence Tomography (AS-OCT) in Two Recession Surgeries

Study Overview
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Brief Summary
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Background and study aims : The investigators conducted this study to compare the movement of extraocular muscle after two types of recession surgery with non-invasive tool called AS-OCT. Who can participate? patients who will undergo two types (conventional method and hang-back method) of typical bilateral lateral rectus recession surgery for correcting intermittent exotropia What does the study involve? Volunteers will attend a clinic for four visits over three months. They will undergo AS-OCT at every visits during follow up period. AS-OCT is non-invasive test to evaluate operation site. The test only requires their cooperation when they undergo AS-OCT. What are the possible benefits and risks of participating? This is non-invasive test for your postoperative follow up. Therefore, there will be no risks about this test. Where is the study run from? Samsung Medical Center When is the study starting and how long is it expected to run for? From April 2015 to Dec 2015

Detailed Description
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This study is a following study of our prior study about AS-OCT in strabismus. The aim of this study is to compare the longitudinal changes of lateral rectus (LR) muscle insertion between two types of bilateral recession surgery. An AS-OCT scan of the LR muscle was performed every visits. Data on gender, age, degree of deviation (prism diopter), and spur-LR insertion distance using AS-OCT were collected at postoperative months 1,3 in each group.

Official Title
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Comparison of the Changes of Lateral Rectus Muscle Insertion Measured With AS-OCT in Two Recession Surgeries

Conditions
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Intermittent Exotropia

Intervention / Treatment
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* Procedure: lateral rectus recession (bilateral)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients who will undergo bilateral lateral rectus recession surgery for correcting intermittent exotropia Exclusion Criteria: previous ocular surgery other ocular diseases except intermittent exotropia amblyopia

Ages Eligible for Study
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Minimum Age: 5 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| conventional lateral rectus recession<br>This is the standard technique for recession with two single-armed sutures.Exposure of the rectus muscle insertion includes freeing the insertion and proximal muscle borders sufficiently to place the sutures. And the needle is passed through the tendon avoiding the anterior ciliary arteries. If the sutures are passed as shown a true knot is formed, and the muscle is detached. Then a caliper measures from the limbus or the original insertion. A passage of the needle through sclera. The recessed muscle is ideally parallel to the old insertion (or nearly so). Conjunctival incision was finally sutured. | Procedure: lateral rectus recession (bilateral)<br>* Two types of recession (conventional or hang-back method) are typical surgeries for correcting intermittent exotropia. It depends on surgeon's decision at the time of surgery.<br>|
| hang-back lateral rectus recession<br>The hang-back recession has been described as a simple, safe alternative to conventional recession. The procedure is said to be less likely to result in scleral perforation because needles are placed through relatively thicker sclera near the insertion site. It is the modified techique for recession with one double-armed sutures. | Procedure: lateral rectus recession (bilateral)<br>* Two types of recession (conventional or hang-back method) are typical surgeries for correcting intermittent exotropia. It depends on surgeon's decision at the time of surgery.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The change of limbus-muscle insertion distance measured with AS-OCT |  | baseline and 1.3 months |