V-pattern and accommodative convergence/accommodation ratio in consecutive esotropia after surgery for intermittent exotropia: A comparison of bilateral lateral rectus recession and unilateral recession

Abstract

Objective

To delineate a clinically actionable phenotype of consecutive esotropia with V-pattern following surgery for intermittent exotropia and to determine whether the initial surgical approach—bilateral lateral rectus recession versus unilateral recession–resection—is associated with differential patterns of V-pattern presentation and accommodative convergence/accommodation behavior among patients who develop consecutive esotropia. Clarifying these associations may inform postoperative surveillance and the selection of secondary surgical strategies in consecutive esotropia complicated by pattern deviation.

Methods

We retrospectively reviewed patients who developed consecutive esotropia after surgery for intermittent exotropia and were evaluated/managed at our center between 2016 and 2024. Thirty-four patients with consecutive esotropia had previously undergone bilateral lateral rectus recession (bilateral lateral rectus recession group), and twenty-six had previously undergone recession–resection (recession–resection group). Intermittent exotropia stage and consecutive esotropia clinical data were extracted, including ocular motility (with emphasis on abduction limitation), refractive status, presence and magnitude of V-pattern, and accommodative convergence/accommodation ratio measured using the gradient method. Comparisons were performed between groups at each stage and within individuals across the intermittent exotropia-to-consecutive esotropia transition.

Results

Baseline distance exodeviation was comparable between groups (bilateral lateral rectus recession: 38.92 ± 12.78^Δ at 6 m and 36.47 ± 13.47^Δ at 33 cm; recession–resection: 39.04 ± 12.91^Δ at 6 m and 40.60 ± 10.54^Δ at 33 cm), whereas near exodeviation was greater in the recession–resection group than in the bilateral lateral rectus recession group. No patient demonstrated a preoperative pattern deviation. Among consecutive esotropia cases, V-pattern was observed more frequently in the bilateral lateral rectus recession–derived consecutive esotropia cohort than in the recession–resection–derived cohort (15/34 vs. 3/26). During intermittent exotropia stage, accommodative convergence/accommodation ratios did not differ between groups; however, accommodative convergence/accommodation ratios increased after consecutive esotropia onset and were higher in the bilateral lateral rectus recession–derived consecutive esotropia cohort than in the recession–resection–derived cohort. These findings indicate that, once consecutive esotropia develops, the postoperative phenotype may vary according to initial procedure, with a stronger association between bilateral lateral rectus recession–derived consecutive esotropia and both V-pattern presentation and elevated accommodative convergence/accommodation.

Conclusions

Among patients who developed consecutive esotropia after intermittent exotropia surgery, bilateral lateral rectus recession–derived consecutive esotropia was more commonly accompanied by V-pattern and a higher accommodative convergence/accommodation ratio than recession–resection–derived consecutive esotropia. The increase in accommodative convergence/accommodation from the intermittent exotropia stage to the consecutive esotropia stage suggests that accommodative mechanisms may contribute to the consecutive esotropia-with-pattern phenotype and should be assessed when planning postoperative monitoring and secondary correction. Importantly, this study characterizes phenotypic differences among consecutive esotropia cases and does not estimate the incidence of consecutive esotropia or V-pattern consecutive esotropia after bilateral lateral rectus recession or recession–resection.

Keywords

Consecutive esotropia V-pattern accommodative convergence/accommodation bilateral lateral rectus recession unilateral recession combined with medial rectus resection

Introduction

Consecutive esotropia (CET) is an important postoperative complication following surgical correction of exotropia, with reported rates ranging from approximately 6%–20%.¹ Mild early overcorrection is often considered desirable to reduce recurrent exotropia; however, persistent esodeviation may lead to diplopia, sensory deterioration, amblyopia, and loss of stereoacuity.^2,3 Prior studies have reported potential clinical correlates of CET, including a high accommodative convergence/accommodation (AC/A) ratio, lateral incomitance, divergence-excess type, younger age at surgery, large immediate postoperative overcorrection, and type of surgical procedure.^4–7 Despite these observations, the phenotype of CET complicated by pattern deviation, particularly V-pattern, remains incompletely characterized.⁸ From a practical standpoint, V-pattern CET may pose additional challenges for postoperative assessment and secondary surgical planning. Therefore, in this retrospective study, we focused on patients who developed CET following surgery for intermittent exotropia (IXT) and compared the prevalence and clinical features of V-pattern and AC/A behavior between CET cases following bilateral lateral rectus recession (BLR) and those following unilateral recession–resection (R&R).

Materials and methods

Study settings and participants

The study was conducted in accordance with the Declaration of Helsinki of 1975, as revised in 2024, and was approved by the Ethics Review Committee of Tianjin Eye Hospital (Approval Number: 2022004). All patient details were deidentified before analysis. The reporting of this retrospective study conforms to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.⁹ Written informed consent, including permission to use relevant clinical data and images for research purposes, was obtained from the parents or legal guardians of all participants at the time of readmission for clinical re-evaluation. We retrospectively reviewed the medical records of patients who underwent surgery for IXT at Tianjin Eye Hospital between January 2016 and March 2024, including BLR and R&R (lateral rectus recession combined with medial rectus (MR) resection). During this period, approximately 20,280 IXT surgeries were performed at our center, providing the clinical context for the present cohort. Eligible CET cases were retrospectively identified from this surgical population based on predefined inclusion and exclusion criteria. The study population included patients who developed postoperative CET after BLR or R&R and who underwent further assessment at our center. CET was defined as an esodeviation of ≥5 prism diopters (Δ) in primary position persisting for at least 4 weeks following surgery. A clinical V-pattern was defined as a ≥15^Δ increase in the esodeviation angle in downgaze compared with that in upgaze. Patients were excluded if they had preoperative pattern deviation, oblique muscle dysfunction, fundus torsion on fundus photography, preoperative abnormal ocular motility, dissociated vertical deviation (DVD), or dissociated horizontal deviation (DHD). Abduction limitation emerging after the initial surgery was documented but was not used as an exclusion criterion.

Ocular examinations

A detailed medical history was obtained, including information related to IXT and prior strabismus surgery. All patients underwent comprehensive ophthalmologic and orthoptic assessment, including best-corrected visual acuity, cycloplegic refraction, slit-lamp examination of the anterior segment, dilated fundus examination, assessment of fixation preference/dominance, ocular motility evaluation (monocular and binocular versions), and stereoacuity testing using the Titmus test. Horizontal and vertical deviations were measured at distance (6 m) and near using the prism and alternate cover test. To assess pattern deviation, ocular alignment in upgaze and downgaze was measured while the patient fixated on a 6 m distant target, with the head positioned at approximately 25° upward (upgaze) and 25° downward (downgaze), respectively, under examiner guidance to ensure standardized head inclination during testing. The magnitude of pattern strabismus was calculated as the difference in horizontal deviation between downgaze and upgaze. Distance-stimulus AC/A ratios were assessed using the gradient method. The angle of deviation was first measured at 6 m using the alternate cover test and recorded in prism diopters (Δ). A −3.00 D lens was then placed before both eyes, and the measurement was repeated under identical conditions. The AC/A ratio was calculated as the change in deviation (Δ) divided by the lens power (D). Patients with refractive error were examined while wearing their full corrective spectacles. Each measurement was repeated three times and averaged. Fundus photography was performed in all patients to assess objective ocular torsion and to document any compensated head posture.

Statistical analysis

Statistical analyses were performed using Statistical Package for the Social Sciences (SPSS) version 25.0 (SPSS Inc.; Chicago, IL, USA). Continuous variables were presented as mean ± SD for approximately normally distributed data or as median (interquartile range (IQR)) for non-normally distributed data. Categorical variables were presented as numbers (percentages). Normality was assessed using the Shapiro–Wilk test. Between-group comparisons (BLR-derived CET vs. R&R-derived CET) were conducted using the independent-samples t test for normally distributed continuous variables and the Mann–Whitney U test for non-normally distributed variables. Categorical variables (including the presence of a V-pattern) were compared using the chi-square test or Fisher’s exact test, as appropriate. Within-participant comparisons between the pre-CET (IXT stage) and post-CET stages (e.g. AC/A ratio) were performed using the paired t test or the Wilcoxon signed-rank test, depending on data distribution. All tests were two-sided, and a p value <0.05 was considered statistically significant.

Results

Clinical characteristics of the two groups (BLR group and R&R group)

In the BLR group, 34 patients (16 males and 18 females) were included. The mean age at exotropia onset was 3.65 ± 2.69 years, and the mean age at the initial corrective surgery was 6.91 ± 3.24 years. The mean spherical equivalent (SE) was −0.53 ± 1.62 D in the dominant eye and −0.36 ± 1.40 D in the nondominant eye, with no significant interocular difference (p > 0.05). One patient had high myopia (−7.00 D in both eyes). The SE distribution was as follows: ≤−5.00 D (n = 1), −5.00 D < SE ≤−2.50 D (n = 5), −2.50 D < SE ≤ 0 D (n = 17), 0 D < SE ≤+2.50 D (n = 10), and > +2.50 D (n = 1). At the IXT stage, the mean distance exodeviation was 38.92 ± 12.78^Δ, and the mean near exodeviation was 36.47 ±13.47^Δ. Stereoacuity was ≤100 arcsec in 74% (25/34) of patients. On postoperative day 1, the mean distance esodeviation was 5.41 ±6.50^Δ, and the mean near esodeviation was 7.38 ± 6.32^Δ (Tables 1 and 2). All patients were readmitted for secondary surgery at a mean interval of 1.45 ± 1.05 years after the initial procedure, ranging from 0.5 to 5 years. At readmission, the mean consecutive esodeviation was 34.09 ± 13.77^Δ at 6 m and 32.09 ± 15.93^Δ at 33 cm. Compared with the IXT stage, stereoacuity was markedly reduced; 6 patients had stereoacuity ≤100 arcsec even when tested in a compensated head posture.

Table 1.

Baseline characteristics.

Factors	BLR group (n = 34)	R&R group (n = 26)	Test statistic	p value
Sex
Male	16	8	χ² = 1.629^a	0.202^a
Female	18	18
Age at IXT surgery
	6.91 ± 3.33	7.36 ± 5.71	U = 395^b	0.642^b
Age at onset
	3.65 ± 2.69	4.10 ± 3.51	U = 409^b	0.805^b
Duration from onset to surgery
	2.53 ± 2.49	3.33 ± 3.82	U = 350^b	0.238^b
SE
Dominant eye	−0.53 ± 1.62	−0.33 ± 2.20	U = 388.5^b	0.575^b
Nondominant eye	−0.36 ± 1.40	−0.05 ± 2.02	U = 379.5^b	0.484^b
Amblyopia
(−)	33	23	–	0.307^c
(+)	1	3
AC/A
	4.23 ± 1.55	3.94 ± 0.58	U = 368^b	0.364^b

Test statistic is reported as χ² for chi-square tests and U for Mann–Whitney U tests.

Chi-square test.

Mann–Whitney U test.

Fisher’s exact test.

AC/A: accommodative convergence/accommodation; BLR: bilateral lateral rectus recession; IXT: intermittent exotropia; R&R: unilateral recession combined with medial rectus resection; SE: spherical equivalent.

Table 2.

Intermittent exotropia.

Factors	BLR group (n = 34)	R&R group (n = 26)	Test statistic	p value
Pre-op exodeviation
33 cm	36.47 ± 13.47	40.60 ± 10.54	U = 246^b	0.039^b
6 m	38.92 ± 12.78	39.04 ± 12.91	U = 259^b	0.099^b
Deviation at distance
≤20 PD	2	3	–	0.109^c
20 PD < deviation ≤40 PD	28	15
>40 PD	4	8
Type of exotropia
Basic	20	13	χ² = 0.795^a	0.731^a
CI	6	7
DE	8	6
Titmus (s)
≤100	25	10	χ² = 7.778^a	0.005^a
>100	7	14
Not assessable	2	2
Deviation at post-op
33 cm	7.38 ± 6.32	7.08 ± 6.60	U = 360.5^b	0.320^b
6 m	5.41 ± 6.50	8.72 ± 6.09	U = 379^b	0.477^b

Stereoacuity was not assessable in some children due to limited cooperation. Test statistic is reported as χ² for chi-square tests and U for Mann–Whitney U tests.

Chi-square test.

Mann–Whitney U test.

Fisher’s exact test.

BLR: bilateral lateral rectus recession; CI: convergence insufficiency; DE: divergence excess; R&R: unilateral recession combined with medial rectus resection.

In the R&R group, 26 patients (8 males and 18 females) were included. The mean age at exotropia onset was 4.10 ± 3.51 years, and the mean age at the initial corrective surgery was 7.36 ± 5.71 years. The mean SE was −0.33 ± 2.20 D in the dominant eye and −0.05 ± 2.02 D in the nondominant eye, with no significant interocular difference (p > 0.05). The SE distribution was as follows: ≤−5.00 D (n = 1), −5.00 D < SE ≤−2.50 D (n = 2), −2.50 D< SE ≤ 0 D (n = 11), 0 D < SE ≤+2.50 D (n = 11), and > +2.50 D (n = 1). At the IXT stage, the mean distance exodeviation was 39.04 ± 12.91^Δ, and the mean near exodeviation was 40.60 ± 10.54^Δ, and 38% (10/26) had stereoacuity ≤100 arcsec. On postoperative day 1, the mean distance esodeviation was 8.72 ± 6.09^Δ, and the mean near esodeviation was 7.08 ± 6.60^Δ (Tables 1 and 2). Patients were readmitted at a mean of 1.43 ± 1.13 years after the initial surgery, ranging from 0.5 to 5 years. At readmission, the mean consecutive esodeviation was 30.36 ± 18.02^Δ at 6 m and 27.28 ± 18.16^Δ at 33 cm. A total of 10 patients had stereoacuity ≤100 arcsec, and 3 patients had a concomitant V-pattern with abnormal head posture.

Comparison of V-pattern between groups

During the preoperative IXT stage, no patient in either group demonstrated a V- or A-pattern deviation, oblique muscle overaction, or concomitant vertical deviation.

At readmission with CET, the BLR group (n = 34) demonstrated a mean horizontal esodeviation of 25.97 ± 17.40^Δ in upgaze (25°) and 36.35 ± 15.57^Δ in downgaze (25°) (Table 3). Ocular motility findings were predominantly characterized by abduction lag/limitation. Seven patients showed mild findings suggestive of inferior oblique overaction accompanied by a small vertical deviation (≤5^Δ); however, fundus photography did not demonstrate marked torsion. Diplopia was reported in some patients, and among patients with a V-pattern, 15 exhibited a mild compensatory chin-up head posture.

Table 3.

Consecutive esotropia.

Factors	BLR group (n = 34)	R&R group (n = 26)	Test statistic	p value
Duration from IXT to CET surgery
	1.45 ± 1.05	1.43 ± 1.13	U = 424^b	0.988^b
Pre-secondary surgery esodeviation
33 cm	32.09 ± 15.93	27.28 ± 18.16	U = 361.5^b	0.327^b
6 m	34.09 ± 13.77	30.36 ± 18.02	U = 332^b	0.150^b
Upgaze	25.97 ± 17.40	24.92 ± 19.52	U = 386.5^b	0.553^b
Downgaze	36.35 ± 15.57	29.52 ± 19.66	U = 298^b	0.050^b
V-pattern
(+)	15	3	–	<0.001^c
(−)	19	23
AC/A
	6.83 ± 1.58	5.17 ± 0.92	U = 205^b	0.001^b
Titmus (s)
≤100	6	14	χ² = 2.524^a	0.111^a
>100	28	10
Type of surgery
LRA	19	13	–	<0.001^c
MR recession	12	1
LRA + MR recession	3	12
Deviation post-op
33 cm	2.59 ± 4.16	−1.20 ± 5.30	U = 173^b	<0.001^b
6 m	1.44 ± 4.59	0.72 ± 4.64	U = 392^b	0.613^b

Test statistic is reported as U for Mann–Whitney U tests and χ² for chi-square tests.

Chi-square test.

Mann–Whitney U test.

Fisher’s exact test.

BLR: bilateral lateral rectus recession; LRA: lateral rectus advancement; R&R: unilateral recession combined with medial rectus resection; AC/A: accommodative convergence/accommodation; MR: medial rectus.

In the R&R group (n = 26), the mean horizontal esodeviation at readmission was 24.92 ± 19.52^Δ in upgaze (25°) and 29.52 ± 19.66^Δ in downgaze (25°) (Table 3). Three patients had a V-pattern accompanied by inferior oblique overaction, and ocular motility examination also revealed abduction lag, with upgaze–downgaze differences of 18^Δ, 20^Δ, and 22^Δ, respectively.

Overall, V-pattern was observed more frequently among CET cases in the BLR group than in the R&R group (15/34 vs. 3/26, p < 0.001). Among the BLR-derived CET cases with V-pattern, the preoperative IXT subtypes were basic type in 10 patients, divergence-excess type in 2 patients, and convergence-insufficiency type in 3 patients. All 3 V-pattern cases in the R&R-derived CET group had basic-type IXT before the initial surgery.

Comparison of AC/A ratio between groups

During the pre-CET IXT stage, the mean AC/A ratio (gradient method) was 4.23 ±1.55 in the BLR group and 3.94 ± 0.58 in the R&R group, with no significant between-group difference (p > 0.05). At readmission after the onset of CET, AC/A ratios increased and differed significantly between groups: 6.83 ± 1.58 in the BLR group (n = 34) versus 5.17 ± 0.92 in the R&R group (n = 26) (p < 0.001; Figure 1).

Figure 1.

The AC/A ratio was assessed using the gradient method in 34 patients in the BLR group (6.83 ± 1.58) and 26 patients in the R&R group (5.17 ± 0.92) at the time of readmission for consecutive esotropia, with a significant difference observed between the two groups. AC/A: accommodative convergence/accommodation; BLR: bilateral lateral rectus recession; R&R: unilateral recession combined with medial rectus resection.

Consecutive esotropia correction

All patients with consecutive esotropia in the BLR group (n = 34) and the R&R group (n = 26) underwent secondary corrective surgery under general anesthesia, performed by the same surgeon (WZ). The secondary procedure was individualized according to the magnitude of esodeviation, ocular motility (particularly abduction limitation), and intraoperative forced duction test findings.

In the BLR group, secondary surgical procedures included lateral rectus advancement (LRA) in 19 patients, MR recession in 12 patients, and combined LRA plus MR recession in 3 patients (Table 3). In the R&R group, 13 patients underwent LRA, 1 patient underwent MR recession, and 12 patients underwent combined LRA plus MR recession (Table 3). The distribution of secondary surgical types differed significantly between groups (p < 0.001).

Postoperatively, the near deviation at 33 cm was 2.59 ± 4.16^Δ in the BLR group and −1.20 ± 5.30^Δ in the R&R group (p < 0.001). The distance deviation at 6 m was 1.44 ± 4.59^Δ in the BLR group and 0.72 ± 4.64^Δ in the R&R group, with no significant between-group difference (p = 0.613) (Table 3).

Supplementary intraoperative/clinical observations

In patients with abduction lag/limitation, forced duction testing and intraoperative exploration were used to guide the surgical plan. In several cases, the lateral rectus was found to be located slightly posterior to that documented in the initial operative record, without obvious muscle slippage. In one case from the R&R group, intraoperative exploration revealed the lateral rectus insertion to be 16 mm from the limbus after the initial procedure (initial surgery: 4-mm lateral rectus recession combined with 4-mm MR resection). A small subset of patients required a third procedure because of persistent esotropia after secondary correction. In patients with V-pattern and/or mild findings suggestive of inferior oblique overaction accompanied by small-angle vertical deviation, vertical transposition during horizontal rectus surgery or MR recession was performed as needed. Compensatory head posture and pattern deviation improved postoperatively. Overall, ocular motility and primary-position alignment improved after secondary correction.

Discussion

Consecutive esotropia is an important postoperative complication that may impair binocular vision and lead to diplopia, suppression, amblyopia, and loss of stereoacuity. For small early postoperative esodeviations, conservative management, including refractive correction, alternate patching, and prism therapy, is generally recommended. Surgical intervention is often considered when esodeviation exceeds 10^Δ and persists for more than 6 months.¹⁰

Previous studies have linked CET to several clinical factors, including a high AC/A ratio, lateral incomitance, divergence-excess exotropia, younger age at surgery, marked early overcorrection, and surgical procedure type.^4–7 Kim et al.⁶ reported that CET occurred more frequently after BLR in divergence-excess exotropia and that a substantial proportion of these patients required secondary surgery. Xie et al.^11,12 compared BLR and R&R for large-angle exotropia and suggested that BLR may provide favorable long-term alignment with modest early overcorrection, although sensory consequences were also observed. In a cohort of 177 patients with BLR, postoperative monofixation syndrome and CET requiring correction were reported. Jang et al.¹³ suggested that a preoperative exotropia angle of 25^Δ–40^Δ might be associated with CET. In our series, most patients in both groups fell within this range. However, other studies have not reported a consistent relationship between preoperative exotropia angle and CET and have instead emphasized factors such as AC/A ratio, lateral incomitance, divergence-excess type, and early postoperative overcorrection.^4–6

In this retrospective study of patients who developed CET after IXT surgery, we compared BLR-derived and R&R-derived CET phenotypes, with particular attention to V-pattern and AC/A behavior. During the pre-CET exotropia stage, stereoacuity appeared better in the BLR group than in the R&R group; however, after CET onset, stereoacuity was similarly reduced in both groups. More importantly, V-pattern was observed more frequently in the BLR-derived cohort. AC/A ratios did not differ between groups during the pre-CET exotropia stage; however they were significantly higher in BLR-derived CET cases at readmission. Collectively, these findings suggest that once CET develops, its clinical phenotype may differ according to the initial procedure, with BLR-derived CET more often showing a profile of V-pattern and elevated AC/A. In addition, the greater downgaze deviation observed in the BLR-derived CET group showed only borderline statistical significance (p = 0.050), suggesting a possible trend toward more pronounced pattern-related deviation that should be interpreted cautiously given the limited sample size.

Several mechanisms may contribute to CET after BLR, including increased MR tension, altered innervation, and increased tonic convergence.^14–16 Prolonged near work has also been proposed as an aggravating factor. Prior studies have also examined pattern deviation after horizontal muscle surgery in relation to oblique muscle dysfunction.¹⁷ In one study of children who underwent surgery for comitant esotropia, new-onset vertical strabismus and oblique dysfunction were common, with superior oblique overaction more frequent than inferior oblique overaction, resulting in more A- than V-patterns. The authors suggested that subtle pre-existing oblique dysfunction may have been masked preoperatively or under-recognized because of limited cooperation. In our study, we excluded patients with preoperative pattern deviation, overt oblique muscle dysfunction, dissociated deviations, or objective fundus torsion to minimize confounding from pre-existing pattern mechanisms.^18,19 Nevertheless, at readmission, some patients showed mild findings suggestive of inferior oblique overaction with only small-angle vertical deviation (≤5^Δ), whereas fundus photography did not reveal marked torsion. These findings raise the possibility that, in some CET cases, pattern deviation may reflect postoperative orbital pulley changes or a subtle vertical/oblique imbalance that becomes apparent after horizontal alignment is altered.

Consistent with this concept, a previous study reported that some patients developed A- or V-pattern after BLR with a mean recession amount of 6.2 ± 0.9 mm.⁸ In our cohort, the mean BLR dose was 6.50 ± 3.24 mm. In patients with V-pattern and small vertical components, we applied vertical transposition of the horizontal rectus muscle (approximately half tendon width) during repositioning or MR recession, and both the pattern deviation and compensatory head posture improved postoperatively.²⁰ Orbital imaging studies have also shown that displacement of the lateral rectus pulley, along with smaller displacements of other pulleys, can produce pattern strabismus that mimics oblique muscle dysfunction.^21,22 Taken together, these findings support the possibility that postoperative pulley displacement contributes to CET with V-pattern in selected cases. High-resolution orbital magnetic resonance imaging (MRI) would help clarify this mechanism in future studies.²²

Our data also suggest dynamic changes in AC/A across disease stages. Compared with the pre-CET exotropia stage, AC/A ratios were higher after CET onset, and this increase was more pronounced in BLR-derived CET cases. Previous studies evaluating postoperative AC/A changes have reported mixed findings. Earlier hypotheses suggested that BLR reduces AC/A in esotropic patients and that a high preoperative AC/A decreases after surgery.²¹ Other reports have suggested that postoperative AC/A decreases after BLR or R&R when esotropia is corrected, whereas isolated cases have shown increased AC/A in postoperative esotropia.^23–25 Lee and Lim²⁶ reported a high AC/A ratio in some patients who developed CET after BLR, although AC/A was not assessed during the exotropia stage in that study. A case report also described cyclic esotropia with markedly elevated AC/A after BLR, with intraoperative findings suggesting anatomical changes affecting muscle insertion relationships.²⁷ In our series, the between-group difference in AC/A became evident only after CET onset. Because AC/A was assessed using the gradient method, a relatively high AC/A ratio could still be present despite similar deviations at 6 m and 33 cm. Unlike the heterophoria method, the gradient method measures lens-induced change in deviation at the same fixation distance and is therefore less dependent on the near–distance deviation difference. We speculate that, in BLR-derived CET, elevated AC/A is associated with changes in tonic convergence and MR tension after lateral rectus recession, thereby amplifying accommodative convergence-driven esodeviation. In addition, the lower AC/A ratio observed in the R&R-derived CET group may partly relate to the MR resection component of the initial procedure. Somer et al.²⁸ suggested that resection of the proximal segment of the MR may reduce postoperative AC/A, possibly through effects on proprioceptive feedback. This mechanism may have contributed to the between-group difference observed in our cohort. Whether postoperative AC/A elevation is also influenced by refractive development, such as emmetropization or myopic shift, requires further study.^29–31

An additional clinical consideration is the potential confounding between high AC/A and apparent V-pattern when gaze positions involve different accommodative demands. Using the gradient technique, patients with high AC/A may appear to have greater esodeviation in downgaze if downgaze testing inadvertently induces a nearer fixation distance or greater accommodative effort.¹² In our study, alignment in upgaze and downgaze was measured while patients fixated on a 6 m distant target with standardized head tilt. These measures were intended to minimize the likelihood of a false V-pattern driven purely by accommodative factors. Nevertheless, residual accommodative effects cannot be fully excluded in a retrospective study, and future prospective protocols with stricter control of fixation distance and accommodative state would strengthen interpretation.

From a practical standpoint, our findings support careful preoperative and postoperative evaluation of refractive status, ocular motility, lateral incomitance, pattern deviation, AC/A ratio, and fundus torsion. In patients who develop CET with V-pattern, secondary correction may be tailored according to ocular motility and intraoperative findings. When oblique dysfunction is not prominent and fundus torsion is absent, V-pattern may improve with horizontal rectus advancement or repositioning and/or MR recession combined with vertical transposition, as observed in our surgical experience.

Finally, this study should be interpreted in light of its limitations. It was a retrospective single-center analysis of patients who developed CET and underwent evaluation for secondary management. Therefore, it characterizes phenotypic differences among CET cases rather than estimating the incidence of CET or V-pattern CET after BLR compared with R&R. The limited sample size also restricts generalizability. In addition, some cases excluded due to oblique muscle hyperfunction may have represented postoperative changes rather than definite preoperative abnormalities. Inclusion of such cases in future studies may help clarify whether horizontal muscle surgery is associated with secondary orbital pulley alteration and subsequent pattern deviation. Furthermore, although abduction limitation was documented clinically, detailed subgroup data were not available for a formal retrospective analysis of its association with V-pattern occurrence. Prospective studies incorporating standardized motility grading and orbital imaging would help validate the proposed mechanisms and refine surgical decision making.

Footnotes

Acknowledgments

Not applicable.

Author contributions

Liping Chen, Rui Hao, and Wei Zhang conceived and designed the study. Liping Chen, Yuehe Xu, and Xia Sheng collected the clinical data and performed data curation. Liping Chen performed the data analysis and drafted the manuscript. Rui Hao and Wei Zhang supervised the study, critically revised the manuscript, and approved the final version for submission. All authors read and approved the final manuscript.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author.

Declaration of conflicting interests

The authors declare no competing interests.

Funding

This work was supported by the National Natural Science Foundation of China (No. 82571262), the Tianjin Municipal Metrology Science and Technology Program (Nos. 2025TJMT046 and 2024TJMT032), and the Open Fund of the Institute of Vision Science and Optometry, Nankai University (No. NKSGZ202302).

ORCID iD

Rui Hao

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V-pattern and accommodative convergence/accommodation ratio in consecutive esotropia after surgery for intermittent exotropia: A comparison of bilateral lateral rectus recession and unilateral recession–resection

Abstract

Objective

Methods

Results

Conclusions

Keywords

Introduction

Materials and methods

Study settings and participants

Ocular examinations

Statistical analysis

Results

Clinical characteristics of the two groups (BLR group and R&R group)

Comparison of V-pattern between groups

Comparison of AC/A ratio between groups

Consecutive esotropia correction

Supplementary intraoperative/clinical observations

Discussion

Footnotes

Acknowledgments

Author contributions

Data availability statement

Declaration of conflicting interests

Funding

ORCID iD

References