Risk Factors of Residual Exotropia After Surgery in Patients with Intermittent and Sensory Exotropia: A Systematic Review and Meta-Analysis

Yara S Alhenaki; Mohammed A Alanazi; Amirah A Alanazi; Munira M Albeshr; Faeeqah Almhmoudi; Mohammed A Salawi; Hanan T Aljadani; Eyad M Albarrati; Nawaf I Almaiman

doi:10.2147/OPTH.S598091

. 2026 Sep 18;20:598091. doi: 10.2147/OPTH.S598091

Risk Factors of Residual Exotropia After Surgery in Patients with Intermittent and Sensory Exotropia: A Systematic Review and Meta-Analysis

Yara S Alhenaki ^1,^✉, Mohammed A Alanazi ², Amirah A Alanazi ², Munira M Albeshr ¹, Faeeqah Almhmoudi ³, Mohammed A Salawi ⁴, Hanan T Aljadani ⁵, Eyad M Albarrati ⁶, Nawaf I Almaiman ⁷

PMCID: PMC13599720 PMID: 42781510

Abstract

Background

Residual exotropia remains a common challenge following surgical correction of intermittent exotropia (IXT) and sensory exotropia (SX). Identifying prognostic factors associated with postoperative misalignment is essential to improve surgical planning and long-term outcomes.

Objective

To systematically review and evaluate patient- and surgery-related risk factors for residual exotropia after surgical correction, and to compare these factors between intermittent and sensory exotropia.

Methods

A systematic review was conducted in accordance with PRISMA guidelines. PubMed, Scopus, the Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar were searched from January 2010 to 2025. Eligible studies included patients undergoing surgery for intermittent or sensory exotropia with reported postoperative alignment outcomes. Data extraction and risk-of-bias assessment were performed independently by multiple reviewers, using the MINORS tool for non-randomised studies and the Cochrane RoB 2 tool for randomised trials. The primary synthesis was narrative; where studies were sufficiently comparable, random-effects meta-analyses were additionally performed (single-arm success proportions were pooled with a random-intercept logistic model using maximum-likelihood estimation, and the between-technique odds ratio was pooled by the inverse-variance method with the DerSimonian-Laird estimator).

Results

A total of 53 studies (approximately 7470 patients) were included. Reported surgical success ranged widely, from approximately 38% to 91.6%, depending on the success criterion and follow-up duration. Residual exotropia and postoperative exodrift were consistently reported across studies. Larger preoperative deviation, poor preoperative control, amblyopia, reduced stereoacuity, and sensory exotropia were associated with higher rates of residual deviation and recurrence. Early postoperative alignment emerged as one of the strongest predictors of long-term success, with early overcorrection associated with improved stability. Patients with intermittent exotropia demonstrated better sensory recovery than those with sensory exotropia. The predictive value of risk factors differed by subtype: poor preoperative visual acuity and the chronicity of visual loss dominated in sensory exotropia, whereas fusional control, stereoacuity, and the early postoperative target angle dominated in intermittent exotropia. No statistically significant difference between surgical techniques was detected. On meta-analysis, the pooled surgical success rate was 68.7% (95% CI 63.8–73.2; I² = 89%) and was similar in intermittent (68.3%) and sensory (67.6%) exotropia (test for subgroup differences, P = 0.42), and bilateral lateral rectus recession and recession-resection did not differ in success (pooled odds ratio 0.88, 95% CI 0.51–1.52).

Conclusion

Residual exotropia after surgery is influenced by multiple patient- and surgery-related factors, particularly preoperative sensory status and early postoperative alignment, with a modest early overcorrection (a small postoperative esodeviation) associated with greater long-term stability. Intermittent and sensory exotropia differ in functional outcomes, underscoring the importance of individualized surgical planning and long-term follow-up. Standardized outcome definitions and prospective studies are needed to improve comparability and long-term outcome prediction.

Keywords: intermittent exotropia, sensory exotropia, residual exotropia, strabismus surgery, surgical outcome

Introduction

Exotropia is the outward deviation of one eye. It can be constant or intermittent. The deviating eye may always be the same eye, or it may alternate.¹ It is either congenital or acquired. These can be concomitant or incomitant. Concomitant exotropia refers to a divergent deviation that remains the same in all positions of gaze. On the other hand, incomitant exotropia refers to divergent deviation of the visual axis that differs with the position of gaze.² Comitant exotropia is further divided into primary (infantile or intermittent) and secondary (sensory or consecutive) exotropia.³ Intermittent exotropia is the most common form of strabismus. It is characterized by occasional outward deviation of the eyes. In contrast, sensory exotropia occurs when one eye deviates outward as a result of longstanding poor vision or loss of vision in that eye.⁴ Global Prevalence of exotropia as reported by Hashemi et al Their systematic review had pooled the prevalence of 1.23%.⁵ In Saudi Arabia, exotropia represents around 16.9–26.9% of paediatric strabismus cases.⁶^,⁷ Management of exotropia depends on the type and associated ocular findings. Treatment options can be divided into non-surgical and surgical methods. Non-surgical options for intermittent exotropia include refractive error correction, over-minus therapy, prism therapy, and orthoptics. When the exodeviation occurs more than 50% of waking hours with a gradual loss of fusional control, surgical management might be needed. Surgical options include bilateral lateral rectus recession, unilateral medial rectus resection with lateral rectus recession, augmented bilateral lateral rectus recession, and super maximal unilateral recession resection procedure.² Surgery success rates range from 38–91.6%, depending on follow-up and the criteria used to determine success. There are no clearly identified risk factors for poor surgical outcomes.^8–12 Improving surgical outcomes in exotropia requires a clear understanding of the factors that may increase the likelihood of poor postoperative alignment. Previous studies have examined several commonly discussed predictors, including age at the time of surgery, the magnitude of preoperative deviation, sensory status, amblyopia, and the type of surgical procedure performed, yet their findings remain inconsistent, and no single risk factor has been universally confirmed.^8–12 This variability across the literature underscores the need for a more unified evaluation of the determinants of residual misalignment.

Residual exotropia is one of the most frequently encountered postoperative complications following surgical correction of both intermittent and sensory exotropia. It can significantly affect functional visual outcomes and cosmetic satisfaction.^8–12 Persistent or recurrent exotropia may require prolonged follow-up and, in some cases, additional surgical intervention. This underscores the importance of identifying risk factors to help clinicians anticipate surgical success and tailor management plans accordingly. Although multiple studies have examined postoperative outcomes in exotropia, a notable gap in the literature persists. Specifically, very few studies have directly compared intermittent exotropia (IXT) and sensory exotropia (SX) regarding the likelihood of developing residual exotropia and the factors associated with it. This gap is particularly important given the distinct nature of the two conditions: intermittent exotropia is the most common form of pediatric strabismus,⁴ while sensory exotropia results from unilateral visual impairment that disrupts binocular fusion.⁴ Understanding how these differences influence postoperative alignment may provide meaningful insight into why surgical outcomes vary between the two groups. Moreover, prognostic factors for residual exotropia remain inconsistently reported, outcome definitions vary widely across studies, and no recent synthesis has integrated both patient-related and surgery-related predictors across intermittent and sensory exotropia. Clarifying these determinants has direct clinical value for preoperative surgical counseling, procedure selection, realistic expectation-setting regarding postoperative exodrift and recurrence, and the identification of patients at higher risk of reoperation. For these reasons, the aim of this systematic review is to identify and evaluate the risk factors associated with residual exotropia after surgical correction, and to compare these factors between patients with intermittent exotropia and those with sensory exotropia. By synthesizing available evidence, this study seeks to improve the ability to predict postoperative outcomes and support more informed, individualized clinical decision-making.

Methods

Protocol and Registration

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.¹³ The protocol was developed a priori to outline the objectives, eligibility criteria, search strategy, and methods for study selection and data extraction.

Study Design and Settings

This study is a systematic review with narrative synthesis, aimed at identifying preoperative and intraoperative factors associated with residual exotropia following surgical correction of intermittent or sensory exotropia. Owing to substantial methodological and outcome heterogeneity across the included studies, the primary synthesis was narrative and was structured as follows: extracted findings were grouped into patient-related and surgery-related determinants, and for each determinant the direction and consistency of its association with residual exotropia, recurrence, or reduced surgical success were summarised across studies (a vote-counting approach). Reported success, recurrence, overcorrection, and undercorrection proportions were tabulated by surgical technique and by exotropia subtype, and where studies provided adjusted effect estimates (odds or hazard ratios with confidence intervals or p-values) these were extracted. Findings were interpreted separately for intermittent and sensory exotropia to address the comparative objective. In addition, where a sufficient number of studies reported a common comparison (bilateral lateral rectus recession vs recession-resection) or a common outcome (surgical success), random-effects meta-analyses were performed in R (meta package). The single-arm pooled proportion of surgical success was estimated with a random-intercept logistic regression (generalised linear mixed) model, using maximum-likelihood estimation of the between-study variance and a logit transformation, whereas the between-technique odds ratio (bilateral lateral rectus recession vs recession-resection) was pooled by the inverse-variance method with the DerSimonian-Laird estimator, with 95% confidence intervals, heterogeneity quantified by I-squared, subgroup analysis by exotropia subtype, leave-one-out sensitivity analysis, and small-study effects assessed by funnel plot and Egger test. The review included published studies conducted in hospital, clinical, and surgical settings across different populations and age groups. Only peer-reviewed original articles were considered.

Search Strategy and Screening Process

A comprehensive literature search was conducted using four sources: PubMed, Scopus, the Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar. The search was performed using a combination of relevant keywords and Medical Subject Headings (MeSH) related to exotropia, surgical correction, and postoperative residual deviation. Google Scholar search results were screened manually to identify the most relevant articles. Additionally, the reference lists of all included studies were reviewed to ensure that no eligible publications were missed. The search covered studies published from January 2010 to 2025, with no geographic restriction; the reference lists of all included studies were additionally hand-searched to capture landmark studies. The full search strings for each database are provided in Supplementary Material S1.1 (PubMed, S1.2 (Scopus, S1.3 (CENTRAL, and S1.4 (Google Scholar. The screening process was carried out by two independent pairs of reviewers, working in duplicate at each stage. The screening method is described in full in Supplementary Material S1.6.

Title and abstract screening: Each article was reviewed independently by both reviewers within the pair. Studies that appeared relevant or potentially relevant were moved to full-text assessment.

Full-text screening: The same reviewer pairs independently evaluated the full texts against the predefined inclusion and exclusion criteria.

A study was included only when both reviewers in the pair agreed that it met all eligibility criteria. Disagreements at any stage were resolved through discussion within the reviewer pair. If consensus could not be reached, a third senior reviewer was consulted to make the final decision.

Inclusion and Exclusion Criteria

Inclusion Criteria

Population: Patients of any age diagnosed with intermittent or sensory exotropia undergoing surgical correction.

Exposure: Preoperative or intraoperative characteristics associated with residual exotropia (eg, age at surgery, preoperative angle, amblyopia, refractive error, surgical technique).

Outcome: Postoperative residual exotropia.

Study Design: Observational studies and randomized controlled trials.

Language: English-language publications.

Exclusion Criteria

Non-original articles (reviews, editorials, conference abstracts without data).

Case reports or case series with fewer than 10 patients.

Studies lacking clear outcome definitions or without extractable data regarding risk factors.

Data Extraction

Data extraction for the included studies was conducted using a Google Sheet specifically designed for this systematic review.

The sheet included multiple structured columns detailing the essential characteristics of each study, such as the article ID, authors’ names, year and country of publication, study design, and sample size.

Patient-related information—including the type of exotropia, age, and associated comorbidities such as amblyopia or anisometropia—was also recorded.

Additionally, data regarding the surgical technique (eg, bilateral lateral rectus recession, unilateral recess–resect), surgery setting, type of surgery (primary or revision), follow-up duration, and number of reoperations were extracted.

The main outcome measures included the presence or absence of residual exotropia, the degree of postoperative deviation (in prism diopters), and the rate of surgical success.

Reported complications such as overcorrection, undercorrection, diplopia, or consecutive esotropia were also documented, along with the measurement tools used in each study (eg, prism cover test, Worth 4-dot, Bagolini lenses).

All data were independently extracted by two reviewers using the same standardized extraction sheet to ensure methodological consistency and accuracy.

Quality Assessment/Risk of Bias

A thorough methodological quality assessment was conducted for all included studies.

The majority of included studies were non-randomized comparative studies; these were appraised using the Methodological Index for Non-Randomized Studies (MINORS) tool to evaluate their internal validity and risk of bias.¹⁴ For the small number of randomized controlled trials, methodological quality was instead assessed using the Cochrane Risk-of-Bias tool for randomized trials (RoB 2). The completed RoB 2 assessments are presented in Supplementary Material S2.1 and the completed MINORS assessments in Supplementary Material S2.2.

This validated instrument consists of 12 items: 8 core items applicable to all non-randomized studies and 4 additional items specific to comparative designs.

Each item was scored as 0 (not reported), 1 (reported but inadequate), or 2 (reported and adequate), resulting in a maximum total score of 24 for comparative studies.

Each study was assessed independently by two reviewers, and any disagreements were resolved by a third (arbitrating) reviewer. Inter-reviewer agreement prior to arbitration is reported in Supplementary Material S2.5.

This comprehensive evaluation ensured that only studies with sufficient methodological rigor contributed to the final synthesis of evidence in this systematic review.

Ethical Approval

This research project obtained ethical approval from the Research Ethics Committee (REC) of King Fahd Armed Forces Hospitals - Jeddah, under the approval number REC 846 (NCBE-KACST Registration No: H-02-J047). The project, titled “Risk Factors of Residual Exotropia After Surgery in Patients with Intermittent and Sensory Exotropia: A Systematic Review and Meta-Analysis”, was reviewed and approved on September 21, 2025, in accordance with the ethical policies and procedures established by the committee. The study adheres to all institutional and national ethical guidelines. Since the review was based entirely on previously published studies, no new data were collected from human participants.

Results: Study Selection

A total of 1117 records were identified from PubMed and Google Scholar (n = 626), Scopus (n = 317), and the Cochrane Central Register of Controlled Trials (n = 174). After removal of 119 duplicates, 998 records were screened and 935 were excluded at title and abstract. Sixty-three reports were sought for retrieval, of which 2 could not be retrieved. Of the 61 reports assessed for eligibility, 8 were excluded (5 lacked a control group, one off-scope study with a nutritional focus, one conference abstract without an internal control group, and one out-of-scope technology intervention), yielding 53 studies included in the review (Figure 1).¹⁵ The derivation and reconciliation of the record counts across the four sources are provided in Supplementary Material S1.5.

Study selection flowchart: identification, screening, inclusion steps via databases and registers. The flowchart illustrates the process of study selection via databases and registers. It begins with the identification phase, where 1117 records are identified from databases including PubMed and Google Scholar (626), Scopus (317) and Cochrane CENTRAL (174). No records are identified from registers. In the next step, 119 duplicate records are removed, leaving 998 records for screening. During the screening phase, 935 records are excluded, resulting in 63 reports sought for retrieval. Two reports are not retrieved, leaving 61 reports assessed for eligibility. In the eligibility assessment, 8 reports are excluded for reasons such as no control group (5), off-scope nutritional focus (1), conference abstract without an internal control group (1) and out-of-scope technology intervention (1). Finally, 53 studies are included in the review, with 53 reports of included studies. — PRISMA 2020 flow diagram of the study selection process.

Study Characteristics

The 53 included studies, published between 2010 and 2025, were conducted across multiple countries, including the United States (n=6), China (n=9), South Korea (n=12), Egypt (n=9), India (n=4), Iran (n=2), Thailand (n=1), Japan (n=1), Lebanon (n=1), Qatar (n=1), Tunisia (n=1), Malaysia (n=1), Ukraine (n=1), Canada (n=1), Turkey (n=1), and Taiwan (n=1). One study was multicentre (USA and Canada). Study designs consisted predominantly of retrospective cohort studies and retrospective chart review, with a smaller number of prospective clinical studies and randomized controlled trials.

The total sample size ranged widely across studies, approximately 7470 patients were included in this review. Most studies were conducted in tertiary ophthalmology centres or specialized strabismus clinics. The study populations included both children and adults undergoing surgical correction for IXT or SX.

The surgical techniques reported across studies included bilateral lateral rectus recession (BLR), unilateral lateral rectus recession combined with medial rectus resection (recession-resection, R&R), and other modified or augmented procedures depending on the magnitude and type of deviation. Some studies also incorporated adjustable sutures, asymmetric recession techniques, or multi-muscle procedures, as summarized in Table 1.

Table 1.

Characteristics of Included Studies Evaluating Surgical Outcomes and Risk Factors of Residual Exotropia

Study ID	Study Design	Country of Origin	Surgery Setting	Total Number of Patients	Age (Mean ± SD)	Sex, Male (N)	Sex, Female (N)	Type of Surgery Used	Type of Surgery (Primary or Revision Surgery)	Type of Exotropia
Tibrewal 2017¹⁶	Retrospective chart review	India	Dr. Shroff’s Charity Eye Hospital, New Delhi, India and Chittagong Eye Infirmary, Bangladesh	157	14 ± 8.36 years	83	74	Bilateral LR recession/unilateral recess–resect	Primary	IXT
Yang 2016¹⁷	Retrospective cohort study	China	Zhongshan Ophthalmic Center, Sun Yat-sen University, China	40	18.0 ± 8.1 years	17	23	• Two-muscle RR procedure • Three-muscle procedure	Primary	IXT
Pineles 2011¹⁸	Retrospective cohort study	USA	Jules Stein Eye Institute, UCLA	63	Mean age at surgery, by outcome subgroup: orthotropia 12.5 ± 17.4 y; recurrent exotropia 7.1 ± 12.5 y; monofixation (small-angle consecutive esotropia, a favourable functional outcome) 12.8 ± 19.9 y	NR	NR	• Bilateral LR recession. • Recession–resection. • MR resection	Primary	IXT
Yang 2016¹⁹	Retrospective observational study	China	Eye Hospital, Zhongshan Ophthalmic Center, China	1228	13.7 ± 8.8 years	619	609	• RR (unilateral lateral rectus recession + medial rectus resection): 679 (55.7%) • BLR (bilateral lateral rectus recession): 288 (23.6%) • Three horizontal muscles: 119 (9.8%) • Single horizontal rectus: 105 (8.6%) • Binocular medial rectus resection: 29 (2.4%)	primary	IXT
Pineles 2010⁸	Retrospective cohort with prospective re-evaluation (≥10 years follow-up)	United States	surgical center at UCLA	50	28.6 ± 17.6 years	23	27	• Lateral rectus recession (most common) • Medial rectus resection (for convergence insufficiency) • Recession–resection (for basic exotropia) • Adjustable sutures used in some patients	Primary	IXT
Issaho 2017²⁰	Retrospective cohort study	USA	Children’s Medical Center Dallas	118	6.8 ± 2.6 years	48	70	Bilateral lateral rectus (BLR) recession	Primary	IXT
Kim 2014²¹	Retrospective cohort study	South Korea	Yeungnam University Hospital	429	Primary group: 8.27 ± 4.73 years • Resurgery group:5.08 ± 1.68 years	Primary: 166 Resurgery: 34	Primary: 186 Resurgery: 43	Recession–resection (R&R) procedure (unilateral at first, contralateral at second surgery)	Primary surgery: unilateral lateral rectus recession + medial rectus resection • Revision: contralateral R&R (thus both eyes ultimately operated)	IXT
Chalifoux 2016²²	Retrospective, observational, interventional cohort study	Canada	Multicenter (3 hospitals in Montreal, Canada)	102	• CXT: 43 years (16–74) • IXT: 45 years (16–75) • SXT: 43 years (16–72)	NR	Not reported	Medial rectus resection/advancement + lateral rectus recession; adjustable sutures in both groups but applied differently (all muscles vs recessed muscle only)	Both	XT (mixed)
Kim 2023²³	Retrospective cohort	South Korea	South Korea	521	With controllability: Surgery 9.9 ± 8.3 years; onset 7.7 ± 2.8 years • Without controllability: Surgery 8.3 ± 2.4 years; onset 5.6 ± 3.0 years	With controllability: 58 Without controllability: 213	With controllability: 72 • Without controllability:178	• Bilateral lateral rectus (LR) recession • Unilateral LR recession + medial rectus (MR) resection (R&R)	Primary	IXT
Repka 2020²⁴	Secondary analysis of pooled data from a randomized controlled trial (RCT)	United States	Multicenter	197	6.2 ± 2.0	75	122	BLR vs R&R	Primary	IXT
Awadein 2014²⁵	Retrospective cohort (311 pts) + prospective pilot (171 pts)	Egypt	Cairo University	• Retrospective: 311 • Prospective: 171	Standard tables group: 15.9 ± 8.4 years • Modified numbers group: 15.7 ± 8.3 years	Standard group: 156 Modified group: 83	Standard group: 155 • Modified group:88	Bilateral lateral rectus (BLR) recession	Primary	IXT
Kim 2016²⁶	Retrospective cohort study	South Korea	South Korea	212	• Success group: 70.13 ± 43.10 months • Recurrence group: 70.08 ± 53.04 months	122	90	BLR, RR, and ULR depending on deviation type.	Primary	IXT
Jung 2018²⁷	Retrospective cohort study	South Korea	Tertiary referral hospital (Seoul National University Hospital)	64	34.5 ± 14.5 years	35	29	• Unilateral recession–resection (lateral rectus recession + medial rectus resection) of amblyopic eye • Unilateral LR recession only if <25 PD • Adjustable sutures used in 72%	Primary	SX
Lee 2018²⁸	Retrospective interventional study	Taiwan	Chang Gung Memorial Hospital, Taiwan)	101	15.19 ± 12.43 years	52	49	Unilateral recession–resection (RR), Bilateral lateral rectus recession (BLR), other combinations (3–4 muscle surgery, oblique myectomy in some cases)	Primary	IXT
Lee 2020²⁹	Retrospective cohort study	Republic of Korea	Single tertiary care center (Kangbuk Samsung Hospital, Seoul).	248	5.8 ± 1.94 years	137	111	Bilateral lateral rectus (BLR) recession, standardized by Park’s table	Primary	IXT
Kim 2017³⁰	Retrospective cohort study	South Korea	-	121	• Original RR: 6.0 ± 2.3 years • Augmented RR: 5.9 ± 1.9 years	62	59	Unilateral lateral rectus recession + medial rectus resection	Primary	IXT
Hamasaki 2018³¹	Retrospective cohort study	Japan	(Okayama University Hospital & affiliates)	110	23 ± 21 years	51	59	Recess-resect (RR) procedure = lateral rectus recession + medial rectus resection (mean 6.5 ± 1.3 mm each; range 4–9 mm)	Primary	IXT
Song 2020³²	Retrospective cohort study	China	Children’s Hospital of Nanjing Medical University	86	• BLR group: 7.1 ± 2.4 years • R&R group: 6.5 ± 2.7 years	50	36	BLR = symmetric bilateral lateral rectus recession • R&R = unilateral lateral rectus recession combined with medial rectus resection	Primary	IXT
Boichuk 2023³³	Observational cohort study	Ukraine	Routine hospital-based surgical setting at Filatov Institute, Odesa.	59	NR	NR	NR	• Unilateral lateral rectus recession + unilateral medial rectus resection (12 pts, 20%) • Bilateral lateral rectus recession (23 pts, 40%) • Bilateral lateral rectus recession + unilateral medial rectus resection (7 pts, 12%) • Four-muscle surgery (2-stage lateral rectus recession + medial rectus resection) (17 pts, 28%)	Primary	XT (mixed)
El Fekih 2021³⁴	Retrospective cohort study	Tunisia	-	132	6.8 ± 8 years	77	55	• Bilateral lateral rectus recession (most common) • Unilateral recession–resection (LR recession + MR plication) • Three-muscle surgery for >40 PD deviation • Vertical rectus surgery if vertical deviation present • Inferior oblique surgery for oblique overaction	primary	XT (mixed)
Al-Haddad 2020³⁵	Retrospective chart review	Lebanon	Ophthalmology Department, American University of Beirut Medical Center	41	9.2 ± 12.3 years	30	11	Bilateral lateral rectus recession (mean 6.5 ± 1.0 mm)	Primary only, performed by one surgeon	IXT
Yang 2023³⁶	Retrospective study	South Korea	Hospital, under general anesthesia	125	Mean age at diagnosis: 5.7 ± 3.5 years Mean age at surgery: 7.5 ± 3.0 years	55	70	Bilateral LR recession (majority) Slanted BLR for CI-type exotropia	Primary	IXT
Kim 2018³⁷	Retrospective review	South Korea	Seoul National University Bundang Hospital, under general anesthesia	129	6.0 ± 2.3 years (RR group), 6.7 ± 2.4 years (RR-FDT group)	31 (RR group), 31 (RR-FDT group)	33 (RR group), 34 (RR-FDT group)	Unilateral lateral rectus recession and medial rectus resection (RR)	Primary	IXT
PEDIG 2023³⁸	Randomized controlled trial (8-year extension)	Multicenter, United States and Canada	Multicenter academic and community ophthalmology centers in the US/Canada	123	6.5 years	NR	NR	Bilateral lateral rectus recessions (BLRc) vs unilateral lateral rectus recession combined with medial rectus resection (R&R)	Primary	IXT
Kaur 2023³⁹	Retrospective case series	India	Advanced Eye Centre, PGIMER, Chandigarh, India	56	22.9 ± 4.93 y	41	15	Monocular recession–resection procedure in the eye with low vision	Primary	SX
Liu 2019⁴⁰	Prospective cross-sectional clinical study	China	Tianjin Eye Hospital, China	132	10 years	74	58	Unilateral lateral rectus recession (ULR), bilateral lateral rectus recession (BLR), or unilateral lateral rectus recession with medial rectus resection (R&R) depending on deviation angle	Primary surgeries only	IXT
Lee 2018⁴¹	Retrospective review	South Korea	Seoul National University Hospital, South Korea	99	NR	NR	NR	Bilateral lateral rectus recession (6 mm for all patients)	Primary	IXT
Gouda 2022⁴²	Prospective observational controlled study	Egypt	Cairo University, Egypt	136	Early group 3.45 ± 1.04 years; Late group 11.46 ± 5.29 years	50	86	Bilateral lateral rectus muscle recession (average 6.2 ± 1.0 mm; reduced by 0.5 mm in early group)	Primary	IXT
Lai 2019⁴³	Retrospective descriptive clinical study	Malaysia	Sarawak Heart Centre, Malaysia	15	Primary group 6.9 ± 3.13; Secondary group 8.6 ± 1.95	3 (primary), 2 (secondary)	4 (primary), 6 (secondary)	BLR recession (primary); BLR or unilateral LR recession + MR resection (secondary)	Primary only; no reoperations performed	XT (mixed)
Huda 2016⁴⁴	Retrospective clinical study	Qatar	Hamad Medical Corporation, tertiary hospital in Qatar	74	9.1 ± 3.8 years at surgery, onset age 3.6 ± 3.0 years	30	44	Lateral rectus recession, medial rectus resection, or combined recession–resection (unilateral or bilateral)	Primary; secondary procedures in 3 patients (4.1%)	XT (mixed)
Lee 2019⁴⁵	Retrospective cohort study	South Korea	Hospital-based surgical units in South Korea	144	NR	NR	NR	Bilateral lateral rectus recession (BLR) or unilateral lateral rectus recession with medial rectus plication (RP)	Primary	IXT
Fernandez-Ruiz 2018⁴⁶	Retrospective chart review	USA	Pediatric ophthalmology clinics in Michigan (Children’s Hospital, Wayne State University, multi-surgeon study)	95	6.71 ± 3.66 years	48	47	Bilateral lateral rectus recession	Primary	IXT
Li 2025⁴⁷	Retrospective study	China	Joint Shantou International Eye Center, China	101	11.3 ± 4.5 years (non-HM group), 15.1 ± 5.2 years (HM group)	33 (non-HM), 22 (HM)	30 (non-HM), 16 (HM)	Unilateral lateral rectus recession combined with medial rectus resection (R&R), with some cases including IO weakening	Primary	SX (high myopia)
Chun 2020⁴⁸	Prospective clinical study	South Korea	Kyungpook National University Hospital, South Korea	55	9.2 ± 6.2 years	26	29	Slanted bilateral lateral rectus recession (lower fibers recessed more than upper fibers, 1–2 mm difference)	Primary only (exclusion of prior ocular/strabismus surgery)	IXT
Cho 2017⁴⁹	Retrospective study	South Korea	Keimyung University Dongsan Medical Center, South Korea	36	A	NR	NR	Contralateral LR recession and MR resection; modified group reduced surgical dosage by 5 PD from Wright’s surgical table	Secondary surgery for recurrent IXT	IXT
Rajavi 2017⁵⁰	Retrospective cohort study	Iran	Imam Hossein Medical Center, Tehran, Iran	82	NR	27	55	Bilateral LR recession or unilateral LR recession + MR resection (RR)	Primary surgery, with reoperation if deviation ≥20 PD	Infantile XT
Eshaghi 2021⁵¹	Retrospective study	Iran	Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran	194	14.8 ± 8.4 years	62	132	Strabismus surgery tailored to deviation type (horizontal ± vertical; recession/resection combinations; IO weakening in some)	Primary surgeries only	XT (mixed)
Abdelmonem 2022⁵²	Prospective randomized controlled trial	Egypt	University hospitals in Minia and Cairo, Egypt	45	25.6 ± 9.5 years	21	24	Adjustable suture strabismus surgery (sliding noose technique with 6–0 Vicryl)	Primary	XT (mixed)
Kemp 2017⁵³	Retrospective review of sensorimotor outcomes	USA	Boston Children’s Hospital and affiliated centers	274 at distance, 319 at near	NR	NR	NR	Exotropia correction by BLR recession and/or MR resection	Primary surgeries reviewed	IXT
Almabrouk 2019⁵⁴	Prospective clinical study	Egypt	Al-Zahra University Hospital, Egypt	30	15.3 ± 9.98 years	15	15	Unilateral or bilateral lateral rectus recession, with tendon width measured intraoperatively (8–10 mm)	Primary surgeries only	IXT
Ghali 2017⁵⁵	Retrospective clinical study	Egypt	Zagazig University Ophthalmology Department, Egypt	76	13.39 ± 8.37 years	34	42	Bilateral lateral rectus recession (BLR) tailored to deviation angle, LID measured intraoperatively with calipers	Primary	IXT
Erkan Turan 2015⁵⁶	Retrospective review	Turkey	Hacettepe University Faculty of Medicine, Ankara	24	21 ± 13.6 years	14	10	Unilateral recession–resection procedure (eye with poor vision only)	Primary	SX
Han 2023⁵⁷	Retrospective comparative	China	Tertiary strabismus centre	66	NR	NR	NR	BLR vs unilateral recess–resect	Primary	IXT (divergence excess)
Swelam 2025⁵⁸	Randomized controlled trial	Egypt	University hospital	58	4–13 years	NR	NR	Slanted-BLR/improved R&R/augmented-BLR	Primary	IXT (convergence insufficiency)
Patlidanon 2014⁵⁹	Retrospective cohort	Thailand	University hospital	59	mean 7 years	NR	NR	Bilateral LR recession	Primary	IXT
Chaurasia 2021⁶⁰	Retrospective	India	Medical college hospital	30	NR	NR	NR	Unilateral recess–resect	Primary	IXT
Abdelaziz 2021⁶¹	Prospective, nonrandomized	Egypt	University hospital	86	mean 7 years	NR	NR	Recession-based surgery	Primary	Basic IXT
Xie 2019⁶²	Retrospective comparative	China	Tertiary eye hospital	330	~5 years	NR	NR	BLR vs unilateral recess–resect	Primary	IXT (moderate-angle)
Hegazy 2024⁶³	Prospective comparative	Egypt	University hospital	27	10–45 years	NR	NR	Recession–resection vs recession–plication	Primary	Basic IXT
Elgazzar 2025⁶⁴	Prospective randomized	Egypt	University hospital	~40	>4 years	NR	NR	BLR vs unilateral recess–resect	Primary	Basic IXT
Li 2023⁶⁵	Prospective randomized (double-blind)	China	University hospital	34	NR	NR	NR	Slanted vs conventional BLR	Primary	IXT (convergence insufficiency)
Wang 2014⁶⁶	Prospective comparative	China	Provincial hospital	45	children	NR	NR	Three procedures (incl. recess–resect)	Primary	IXT (convergence insufficiency)
Mohan 2013⁶⁷	Retrospective comparative	India	Tertiary eye centre	42	NR	NR	NR	Hang-back vs conventional BLR	Primary	IXT (divergence excess)

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Note: Entries marked “(mixed)” indicate cohorts that included both intermittent and sensory exotropia.

Abbreviations: IXT, intermittent exotropia; SX, sensory exotropia; XT, exotropia; LR, lateral rectus; MR, medial rectus; BLR, bilateral lateral rectus recession; R&R/recess–resect, recession–resection; SD, standard deviation; N, number; NR, not reported; PD, prism diopters.

Quality Assessment of Included Studies

Across the 53 included studies on intermittent and sensory exotropia surgery, overall methodological quality was moderate. The majority were retrospective chart reviews or retrospective cohort studies, with an increasing number of prospective studies and randomized controlled trials among the more recent reports. The non-randomized studies were appraised with the MINORS tool and the randomized controlled trials with the Cochrane RoB 2 tool. Domain-level judgements are summarised in the traffic-light figure in Supplementary Material S2.3, and the overall quality summary is given in Supplementary Material S2.4. This distribution of designs increases the risk of selection bias and information bias. Most studies were single-centre with variable sample sizes. Outcome definitions showed substantial heterogeneity. Success was generally defined as postoperative deviation within ±8–10 prism dioptres (PD) of orthotropia, whereas residual exotropia was defined as >8–10 PD at various postoperative time points. Sensory outcomes such as stereoacuity were inconsistently reported. Follow-up durations ranged from a few months to over 10 years, with some risk of underestimating long-term recurrence due to loss to follow-up. Common methodological limitations included non-consecutive sampling, inconsistent reporting of confounders, and variation in surgical techniques. Given this heterogeneity, the primary synthesis was narrative and, where a sufficient number of studies reported a common outcome, was complemented by random-effects meta-analysis.

Narrative Synthesis

Definitions of Success and Residual Exotropia

Success was most commonly defined as motor alignment within ±8–10 PD of orthotropia at distance. Residual exotropia (>8–10 PD) was reported at different postoperative intervals across studies. Some studies included sensory outcomes, such as deterioration in stereoacuity or the presence of constant esotropia, as part of composite “suboptimal outcome” definitions. Overcorrection was typically defined as esodeviation >5–10 PD.

Motor Alignment and Recurrence

Short-term alignment outcomes were generally favourable, but postoperative exodrift was consistently observed. Recurrence rates increased with time, and Kaplan–Meier analyses demonstrated progressive decline in recurrence-free survival. Early postoperative alignment strongly predicted long-term results: early esotropia was associated with improved stability, whereas early residual exotropia predicted later failure.

Sensory Outcomes

Stereo-acuity and fusion tended to improve in intermittent exotropia after successful alignment, but gains were limited in sensory exotropia. Better preoperative stereoacuity, good near control, and absence of amblyopia were strong predictors of favourable outcomes. A subset of studies included sensory deterioration (eg, ≥2-octave stereo loss) as a failure criterion.

Patient-Related Prognostic Factors

Several patient characteristics influenced outcomes. Large preoperative angles, poor preoperative control, amblyopia, anisometropia, and reduced visual acuity were associated with a higher recurrence rate. The influence of age at surgery varied across studies, with some suggesting higher recurrence rates in very young children, while others found that older age was predictive of worse long-term stability.

Surgical-Related Prognostic Factors

Different surgical approaches showed variable dose–response characteristics. Bilateral lateral rectus recession, unilateral recession–resection, augmented procedures, and asymmetrical techniques all produced good early alignment, but long-term drift differed. Adjustable sutures allowed postoperative refinement and showed benefits in select cohorts. Anatomical factors, such as lateral rectus tendon width and limbus insertion distance, influenced the surgical dose–response. Smaller tendon width and shorter limbus–insertion distance were associated with larger corrective effects per millimetre. Early postoperative alignment (“target angle”) was consistently one of the strongest prognostic factors across studies. Reoperation was more common in patients with large preoperative deviations, early undercorrection, amblyopia, and sensory exotropia. This narrative synthesis highlights consistent predictors of residual exotropia, including a large preoperative angle, poor sensory status, inadequate early overcorrection, and anatomical variations that affect surgical response. Long-term follow-up is essential due to universal exodrift. The expanded comparative evidence reinforced these patterns: reported surgical success ranged from approximately 43% to 91%,⁵⁷^,⁵⁸^,⁶¹^,⁶⁵ with recurrence and undercorrection the principal modes of failure. A large preoperative angle was again a significant risk factor for undercorrection,⁶¹ larger preoperative deviation predicted worse long-term alignment,⁵⁹ and the immediate postoperative (target) angle predicted both recurrence and consecutive esotropia,⁶² reinforcing a modest early overcorrection as a modifiable determinant of success. Direct comparisons of bilateral lateral rectus recession and recession–resection showed no consistent superiority,⁵⁷^,⁶³^,⁶⁷ although one randomized trial favoured recession–resection at one year.⁶⁴ All eleven studies added by the updated search concerned intermittent exotropia, so the evidence base for sensory exotropia remained limited.

Comparison Between Intermittent and Sensory Exotropia

Direct head-to-head comparison between intermittent and sensory exotropia was constrained by the small number of studies focusing specifically on sensory exotropia.²⁷^,³⁹^,⁵⁶ Nevertheless, several patterns distinguished the two subtypes across the available evidence. In intermittent exotropia, the strongest predictors of residual deviation were preoperative fusional control, stereoacuity, the magnitude of the preoperative angle, and the early postoperative alignment or target angle, and successful motor alignment was frequently accompanied by measurable sensory improvement. In sensory exotropia, by contrast, the deviation arises from longstanding monocular visual loss, so preoperative visual acuity and the chronicity of the deviation were the dominant determinants of both motor stability and postoperative drift, whereas sensory recovery remained minimal irrespective of motor success. Amblyopia and reduced stereoacuity were adverse prognostic factors in both groups but carried greater predictive weight in sensory exotropia, in which binocular potential is inherently limited. These observations indicate that although the risk factors overlap, their relative predictive value differs between subtypes. Specifically, in the sensory exotropia studies poorer preoperative visual acuity predicted worse motor outcome and greater exodrift,⁵⁶ and larger, longer-standing deviations were associated with undercorrection and recurrence;²⁷^,³⁹ in intermittent exotropia the corresponding predictors were poor fusional control, reduced stereoacuity, a large distance-near disparity, and failure to achieve a modest early overcorrection (target angle). In direct terms, residual deviation in sensory exotropia appears to be driven mainly by sensory, visual-acuity-driven factors, whereas in intermittent exotropia it appears to be driven mainly by motor and fusional, control- and alignment-driven factors. This comparison remains preliminary, as only three included studies addressed sensory exotropia directly; adequately powered, sensory-exotropia-specific prospective studies are required to confirm subtype-specific predictors.

Meta-Analysis

In the comparison of bilateral lateral rectus recession with unilateral recession-resection (five studies), the two techniques did not differ significantly in surgical success (pooled odds ratio 0.88, 95% CI 0.51–1.52; I-squared = 55%; Figure 2).

A forest plot comparing surgical success odds ratios across studies, with a pooled estimate near 1. BLR vs recession-resection: surgical success. Forest plot with a study table at left and odds ratio plot at right. The x-axis is labeled, Odds Ratio, IV, random, with tick labels 0.2, 0.5, 1, 2, 5. The y-axis lists studies: Song 2020, Han 2023, Xie 2019, Donahue (PEDIG) 2023, Elgazzar 2025, plus Overall (random effects) and Prediction interval. A vertical reference line is at 1. Study odds ratios with 95 percent confidence interval are: Song 2020, 2.68 with 1.02 to 7.05; Han 2023, 1.00 with 0.26 to 3.84; Xie 2019, 0.89 with 0.57 to 1.38; Donahue (PEDIG) 2023, 0.53 with 0.29 to 0.94; Elgazzar 2025, 0.46 with 0.11 to 1.94. Weights percent are 17.8, 11.6, 32.1, 27.8, 10.7, totaling 100.0. The pooled Overall (random effects) estimate is 0.88 with 0.51 to 1.52, shown as a diamond. The Prediction interval is 0.21 to 3.69, shown as a horizontal line. — Forest plot (random-effects) of surgical success: bilateral lateral rectus recession (BLR) vs unilateral recession-resection (R&R). An odds ratio <1 favours R&R; the pooled estimate (OR 0.88, 95% CI 0.51–1.52) indicates no significant difference.

Across 29 cohorts, the pooled surgical success rate was 68.7% (95% CI 63.8–73.2%), with substantial heterogeneity (I-squared = 89%); pooled success was similar in intermittent (68.3%, 95% CI 62.6–73.5%), sensory (67.6%, 95% CI 58.1–75.9%), and mixed (73.1%, 95% CI 67.0–78.4%) exotropia, with no significant difference between subtypes (test for subgroup differences, χ² = 1.72, df = 2, P = 0.42; Figure 3).

A forest plot of surgical success by exotropia subtype, with similar pooled success across subgroups. The forest plot features a table and a confidence interval chart. The table includes columns for Study, Success percent (95% CI), Ev and n, with subgroups: IXT, Mixed and SX. The chart shows events per 100 observations using a generalized linear mixed model. The x-axis ranges from 30 to 90, while the y-axis lists study names. Each study has a point estimate with a 95% confidence interval; pooled results are diamonds. IXT pooled success is 68.3% (95% CI: 62.6-73.5, n=3314). Mixed pooled success is 73.1% (95% CI: 67.0-78.4, n=234). SX pooled success is 67.6% (95% CI: 58.1-75.9, n=126). Overall pooled success is 68.7% (95% CI: 63.8-73.2, n=3674). A vertical dotted line is near 70 on the x-axis. The prediction interval is 41.6-87.1%. — Forest plot of the pooled proportion of surgical success, subgrouped by exotropia subtype (intermittent, sensory, mixed). Pooled success 68.7% (95% CI 63.8–73.2%); subtypes did not differ significantly (test for subgroup differences, P = 0.42).

Leave-one-out analysis confirmed the comparative estimate was robust (pooled odds ratio range 0.73–1.08), and Egger test showed no significant small-study effect for the pooled success proportion (Egger test, p = 0.81; Figure 4).

A scatter plot showing standard error against logit of success proportion from negative 0.5 to 2.0. — Funnel plot assessing small-study effects for the pooled success proportion (Egger test p = 0.81, no significant asymmetry).

Discussion

This systematic review aims to identify and evaluate the risk factors associated with residual exotropia following surgical correction in patients with intermittent exotropia (IXT) and sensory exotropia (SX). Additionally, the review compares postoperative outcomes between these two groups and explores which surgical techniques or timings are more likely to result in residual deviation. Our findings demonstrate that residual exotropia continues to be a common postoperative challenge, largely influenced by variations in preoperative characteristics, intraoperative decisions, and early postoperative alignment. The included studies consistently highlighted the phenomenon of postoperative exodrift, indicating that even procedures with initially favorable alignment may show gradual divergence over time. Across the included studies, success was commonly defined as alignment within ±8–10 prism diopters, while residual exotropia was defined as >8–10 PD at various postoperative time points. These differing definitions contributed to substantial heterogeneity, affecting comparisons across studies. Variability in follow-up duration, the use of sensory criteria, and inconsistent reporting of outcomes further impacted the ability to standardize findings. Such heterogeneity reflects the need for unified diagnostic and postoperative assessment criteria to improve comparability and accuracy in future research. Short-term motor alignment was generally promising; however, nearly all studies documented progressive exodrift with extended follow-up. Kaplan–Meier curves in some papers demonstrated a gradual decline in recurrence-free survival over time. A consistent trend across the literature is that early postoperative alignment is one of the strongest predictors of long-term success. Early overcorrection was associated with improved stability, whereas early residual exotropia strongly predicted future recurrence or undercorrection. These findings emphasize the clinical importance of achieving an appropriate early “target angle” to enhance long-term alignment outcomes. Patients with intermittent exotropia frequently showed improvement in stereoacuity and fusion following successful alignment, whereas patients with sensory exotropia demonstrated limited sensory recovery due to underlying visual deficits. Better preoperative sensory function, absence of amblyopia, and good near control were favourable prognostic indicators. These findings underscore the need to incorporate sensory assessments into the preoperative evaluation, as sensory status significantly influences postoperative stability.

Comparison with Previously Published Literature

The findings of the present systematic review are consistent with the existing international literature on intermittent and sensory exotropia. Across the included studies, postoperative exodrift was a frequently observed phenomenon following surgical correction, with a gradual decline in motor alignment over time.^16–18 Long-term follow-up studies have demonstrated that even patients who achieve satisfactory early postoperative alignment may experience progressive exodrift, emphasizing the difficulty of maintaining long-term orthotropia despite initial surgical success.⁸^,¹⁸ This observation highlights the dynamic nature of ocular alignment following exotropia surgery. Early postoperative alignment emerged as one of the most important prognostic factors in this review, a finding that is strongly supported by prior studies. Several authors have reported that early postoperative overcorrection is associated with improved long-term stability, whereas early residual exotropia is a strong predictor of recurrence.¹⁸^,²¹^,²⁴ This relationship was consistently observed across multiple cohorts and surgical techniques and mirrors the results of the studies included in the present review, reinforcing the clinical importance of achieving an appropriate early target angle in exotropia surgery.⁸^,¹⁹

Patient-related prognostic factors identified in this review are also well supported by the literature. Larger preoperative deviation angles, poor preoperative control, amblyopia, and reduced stereoacuity were consistently associated with higher rates of residual exotropia or recurrence.¹⁶^,²⁵^,²⁶ Similar associations have been reported across studies from Asia, North America, and the Middle East, suggesting that impaired sensory status and suboptimal binocular function negatively influence long-term motor outcomes.²⁷^,⁴⁶^,⁵¹ The effect of age at surgery remained variable across studies, reflecting previously reported conflicting results: some studies suggested worse outcomes in younger children, while others reported increased recurrence in older patients.⁸^,²⁵ With respect to surgical factors, this review’s findings align with previous evidence indicating that no single surgical technique consistently outperforms others across all patient groups. Bilateral lateral rectus recession, unilateral recession–resection and augmented or asymmetrical procedures were all associated with acceptable early outcomes, while long-term stability appeared to depend more on patient characteristics, anatomical factors, and early postoperative alignment than on the surgical approach alone.¹⁷^,¹⁹^,²² Anatomical variables such as lateral rectus tendon width and limbus insertion distance have been shown to influence surgical dose–response and were similarly identified as contributors to outcome variability in the included studies.⁵⁴^,⁵⁵ Reoperation was more frequently required in patients with large preoperative deviations, amblyopia, and early postoperative undercorrection, consistent with previously published reports.²⁴^,⁵⁰

Finally, the differences in sensory outcomes between intermittent and sensory exotropia observed in this review are consistent with prior literature. Patients with intermittent exotropia often demonstrated improvement in stereoacuity and fusion following successful motor alignment, whereas patients with sensory exotropia showed limited sensory recovery due to long-standing visual impairment.⁴⁶^,⁵⁶ These findings further support the importance of preoperative sensory status in predicting postoperative stability and functional outcomes. Importantly, the predictive weight of individual risk factors appears to differ between the two subtypes: in intermittent exotropia, fusional control, stereoacuity, and the early target angle are the principal determinants of long-term alignment, whereas in sensory exotropia the depth and chronicity of monocular visual loss dominate, and sensory recovery remains limited irrespective of motor success. Recognising these subtype-specific differences underscores the need to incorporate sensory evaluation into preoperative counseling and individualized surgical planning. In this regard, the degree of control of the deviation (whether it is manifest or well-controlled/latent) and the preoperative sensory status appear more informative than the absolute angle of deviation alone; accordingly, the surgical target angle is best defined after a preoperative assessment that may include prolonged monocular (Marlow-type) occlusion or prism adaptation to disclose the maximal angle of deviation before dosing.²⁹^,⁴⁸

Strengths, Limitations and Future Directions

This systematic review has several limitations that should be acknowledged. Most included studies were retrospective, which inherently increases the risk of selection and information bias. Substantial heterogeneity in the definitions of surgical success and residual exotropia, as well as variations in follow-up duration, limited the certainty and interpretability of the pooled estimates and of direct comparisons across studies. The included studies were drawn predominantly from Asian, North American, and Middle Eastern centres, with no eligible Western or Central European cohorts captured despite the absence of any geographic restriction; this likely reflects the initial reliance on two databases and represents a potential source of selection bias, which the expanded search across additional databases was intended to mitigate. Conversely, the review did incorporate long-term data, including cohorts with follow-up of ten years or more, which is important given the well-recognised tendency of exotropia to drift with age. Despite these limitations, this review demonstrates several important strengths. It is, to our knowledge, among the first systematic reviews to specifically compare prognostic factors between intermittent and sensory exotropia, an area that has received limited attention in prior literature. The consistent identification of large preoperative deviation, impaired sensory status, and early postoperative undercorrection as risk factors for suboptimal surgical outcomes highlights the robustness of the findings. The comprehensive literature search, rigorous study selection process, and structured synthesis enhance the validity of the conclusions and provide clinically meaningful insights to support surgical decision-making and patient counseling. Future directions should include well-designed prospective randomized controlled trials incorporating standardized outcome definitions and extended follow-up to better assess long-term alignment stability. Additionally, further investigation into early postoperative alignment as a modifiable prognostic indicator may facilitate the development of more individualized and adaptive postoperative management strategies. The updated multi-database search added eleven predominantly intermittent-exotropia comparative studies whose findings were concordant with the pre-existing evidence, strengthening confidence in the identified determinants while underscoring that high-certainty data specific to sensory exotropia remain scarce. In particular, the comparative objective of this review was constrained by the scarcity of sensory-exotropia studies, so the subtype comparison rests largely on the intermittent-exotropia literature contrasted against a small sensory-exotropia evidence base; this asymmetry is a key limitation, and adequately powered, sensory-exotropia-specific prospective studies are a priority for future research.

Conclusion

This systematic review and meta-analysis identifies residual exotropia as a multifactorial complication whose outcome was most consistently associated with a large preoperative deviation, poor fusional control, amblyopia, reduced stereoacuity, and inadequate early postoperative alignment. Pooled surgical success was similar in intermittent and sensory exotropia (approximately 68%), and no statistically significant difference between surgical techniques was detected; the subtypes differed chiefly in the predictive weight of risk factors - visual acuity and the chronicity of visual loss in sensory exotropia vs fusional control, stereoacuity, and the early target angle in intermittent exotropia - and in the potential for sensory recovery. A modest early overcorrection was associated with more stable long-term alignment, although this must be weighed against the risk of consecutive esotropia, and sustained long-term follow-up remains a practical priority; higher-risk patients should be counseled accordingly. Standardized outcome definitions and dedicated prospective studies, particularly in sensory exotropia, are needed to confirm these findings.

Disclosure

The authors report no conflicts of interest in this work.

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PERMALINK

Risk Factors of Residual Exotropia After Surgery in Patients with Intermittent and Sensory Exotropia: A Systematic Review and Meta-Analysis

Yara S Alhenaki

Mohammed A Alanazi

Amirah A Alanazi

Munira M Albeshr

Faeeqah Almhmoudi

Mohammed A Salawi

Hanan T Aljadani

Eyad M Albarrati

Nawaf I Almaiman

Abstract

Background

Objective

Methods

Results

Conclusion

Introduction

Methods

Protocol and Registration

Study Design and Settings

Search Strategy and Screening Process

Inclusion and Exclusion Criteria

Inclusion Criteria

Exclusion Criteria

Data Extraction

Quality Assessment/Risk of Bias

Ethical Approval

Results: Study Selection

Figure 1.

Study Characteristics

Table 1.

Quality Assessment of Included Studies

Narrative Synthesis

Definitions of Success and Residual Exotropia

Motor Alignment and Recurrence

Sensory Outcomes

Patient-Related Prognostic Factors

Surgical-Related Prognostic Factors

Comparison Between Intermittent and Sensory Exotropia

Meta-Analysis

Figure 2.

Figure 3.

Figure 4.

Discussion

Comparison with Previously Published Literature

Strengths, Limitations and Future Directions

Conclusion

Disclosure

References

ACTIONS

PERMALINK

RESOURCES

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