Slanted bilateral lateral rectus recession for convergence insufficiency-type intermittent exotropia: a retrospective study

Association between crystalline lens thickness and intermittent exotropia in children: a cross-sectional observational clinical study

PURPOSE

To investigate the relationship between crystalline lens thickness (LT) and subtypes of intermittent exotropia (IXT) in children, focusing on ocular biometry and accommodation characteristics.

METHODS

This cross-sectional study included 501 children aged from 8 to 12 years: 122 with orthophoria (Group A) and 379 with IXT, which were further categorized into basic type (Group B, n = 254), convergence insufficiency (CI) type (Group C, n = 92), and divergence excess (DE) type (Group D, n = 33). Evaluation of strabismus was measured after diagnostic occlusion. Cycloplegic refraction and assessments of accommodation and convergence functions were performed. All children were examined with Lenstar LS-900 with fixation at non-accommodative target monocularly and ocular biometric parameters including axial length (AL), mean keratometry (Km), central corneal thickness (CCT), LT and aqueous depth (AD) were recorded. Regression analyses were performed to evaluate associations among groups.

RESULTS

The basic type was the most prevalent IXT subtype (67.0%), followed by CI (24.3%) and DE (8.7%). The CI group exhibited greater binocular LT (P = .002) and lower accommodative convergence-to-accommodation (AC/A) ratio compared to the basic type (P = 0.016). Compared to orthophoric controls, the basic IXT group showed greater accommodative amplitude (AMP) (P = 0.004), reduced accommodation lag (P = 0.006), and more distant near point of convergence (NPC) (P < 0.001). Both univariate and multivariate logistic regression analyses indicated that the CI IXT was associated with greater LT (P = 0.006) and lower AC/A ratio (P = 0.007) compared to basic IXT. Basic IXT was correlated with greater AMP (P < 0.001), reduced lag of accommodation (P = 0.002) and more distant NPC (P = 0.003) compared to controls.

CONCLUSIONS

Increased LT and lower AC/A ratio were significantly associated with the CI subtype of IXT in children. The basic type is characterized by greater AMP, reduced accommodation lag, and more distant NPC compared to orthophoric controls. These findings could serve as valuable clinical markers for managing IXT, and contribute to a deeper understanding of the pathophysiology of types of IXT.

Effectiveness of interventions for convergence insufficiency: an observational study evaluating clinical outcomes and health-related quality of life using AS20

BACKGROUND

Convergence insufficiency (CI) is a common condition that can impair visual performance and comfort during close visual work. This observational study evaluated the effectiveness of interventions on clinical outcomes and health-related quality-of-life using the Adult Strabismus-20 (AS20) questionnaire in patients with CI.

METHODS

Data was extracted from a database collected at first consultation from 2015 to 2022. Demographics, interventions and outcomes of 75 patients with CI (mean age 47.2 ± 24.7 years) were analysed.

RESULTS

Orthoptic exercises were prescribed to 58% of patients, 28% received prisms and 9% received no treatment. At the latest follow-up review, 24% were recommended to continue exercises, 24% had prisms, 1 underwent bimedial resection and 1 had treatment with Botulinum Toxin A (BTXA). The median follow-up was 5.0 (0-55) months, 100% were discharged with 25% following failure-to-attend and 11% died. At the latest follow-up, the attendance failure rate was higher for exercises (36%) than for prisms (10%). Both near-prism cover test and near-point of convergence improved from a median of 12 (95% CI 10-14) prism dioptres (PD) to 8.5 (95% CI 6-12) PD, and 17.5 (95%CI 15-20) cm to 10.0 (95%CI 8.3-12.0) cm respectively (p < 0.05). Near-prism fusion range also improved from 10(95%CI 8-14) PD to 16(95% CI 12-20) PD (p < 0.05). The median AS20 score at presentation were 100/100 (30-100) and 47.5/100 (0-100), and post-intervention were 100/100 (75-100) and 70/100 (12.5-97.5) for psychosocial and functional components, respectively.

CONCLUSION

This cohort offers valuable insights into the real-life clinical management of CI in a tertiary adult strabismus centre. However, the study also found that long-term compliance with treatment is intrinsically challenging, emphasising the importance of disease education.

Slanted and Standard Lateral Rectus Recession Procedures for Convergence Insufficiency-Type Intermittent Exotropia in Children: A Retrospective Cohort Study

Purpose

To evaluate the efficacy and safety of slanted bilateral lateral rectus recession (BLR-rec) for treating convergence insufficiency-type intermittent exotropia (CI-IXT) in children.

Methods

In this retrospective cohort study, 26 patients aged <16 years with CI-IXT who underwent BLR-rec between August 2016 and July 2021 with six months of follow-up data post-surgery were classified into slanted BLR-rec group (n = 14) and standard BLR-rec group (n = 12; equal-length recession of the upper and lower horns of the LR muscle). Surgical outcomes were compared between the groups.

Results

In the slanted and standard groups, the preoperative distance exodeviation was 27.9 ± 5.5 and 30.8 ± 10.0 prism diopter (PD) (p = 0.63), near exodeviation was 41.1 ± 5.6 and 42.9 ± 9.2 PD (p = 0.75), and difference between near and distance deviation (N-D deviation difference) was 13.2 ± 3.2 and 12.1 ± 3.3 PD (p = 0.30), respectively. The ratio of postoperative and preoperative N-D deviation difference was compared between the slanted BLR and standard BLR groups at six months postoperatively. The results revealed that the ratio for slanted-BLR was 0.44 ± 0.19, and for standard-BLR was 0.84 ± 0.24. In the standard group, stereoacuity remained unchanged post-surgery compared to that pre-surgery, while the slanted group showed significant improvement (p < 0.05, Wilcoxon signed-rank test).

Conclusion

Compared with the standard BLR-rec procedure, the slanted BLR-rec procedure reduced N-D deviation differences in CI-IXT, positively impacting gross stereopsis.

Effects of slanted bilateral lateral recession vs conventional bilateral lateral recession on convergence insufficiency intermittent exotropia: a prospective study

AIM

To observe the surgical effects of slanted bilateral lateral recession (S-BLR) versus conventional bilateral lateral recession (C-BLR) in convergence insufficiency intermittent exotropia (CI-IXT).

METHODS

Using a randomized, double-blind, prospective design, 22 patients with CI-IXT who were admitted to Renmin Hospital of Wuhan University from July 2019 to December 2020 were included. Patients were randomly divided into either S-BLR or C-BLR group for their subsequent strabismus surgery. All patients were followed up for 12mo. Near deviation, distant deviation, and near-distance difference (NDD) were measured in all patients.

RESULTS

Twelve months after surgery, NDD improvement was 10 (8, 13) prismatic degrees (PD) in S-BLR group and 3 (1, 6) PD in C-BLR group (P=0.011). The near deviation of S-BLR group was 0 (-2, 2) PD, while that of C-BLR group was -4 (-6, -3) PD (P=0.005). Before and after surgery, the difference in the distant deviation between the two groups was not statistically significant. There was no statistically significant difference in near stereopsis between the two groups (P=0.380) at 12mo. The success rate at 12mo after operation was 90.91% and 72.73% in the two groups (P=0.280).

CONCLUSION

CI-IXT patients treated with S-BLR have better surgical outcomes than those treated with C-BLR, which indicates S-BLR is a safe and effective operation pattern.

Intermittent exotropia with convergence insufficiency — diagnostics, methods of invasive treatment

The review analyzes most common injection and surgical methods of treatment of intermittent exotropia of convergence insufficiency: injections of botulinum toxin type A, injections of bupivacaine, bilateral recession of lateral rectus muscles with imposition of fixation sutures or without it (including hemi-hang-back, no-noose technique), recession of lateral rectus muscles according to Stellard, unilateral or bilateral resection of medial rectus muscle, a combination of resection with recession in one eye, the formation of a duplication of medial rectus muscle. The results before and after treatment are presented. The results of evaluating the effectiveness of invasive therapy in patients with exotropia with convergence insufficiency are summed up.

How to Better Treat Patients with Intermittent Exotropia: A Review of Surgical Treatment of Intermittent Exotropia

Intermittent exotropia (X(T)) is the most common form of strabismus, especially in Asians. Treatment of X(T) includes occlusion, overminus lens, and surgery, of which, surgery is the mainstay of treatment. Commonly performed surgical procedures for X(T) are bilateral lateral rectus muscle recession or unilateral lateral rectus recession with medial rectus resection; however, it is unclear which of the two surgeries is more effective. The purpose of this review is to provide an insight on the surgical treatment of X(T). Randomized controlled trials, comparative observational studies, and case series with a large number of patients as well as a long follow-up period of over a year were included.

Treatment of convergence insufficiency type intermittent exotropia with bupivacaine injection to the medial rectus combined with lateral rectus recession

PURPOSE

To evaluate the outcomes of combined bupivacaine HCL (BPX) injection in the medial rectus (MR) muscle with recession of the lateral rectus muscle in the treatment of convergence insufficiency-type intermittent exotropia (CI-IXT).

METHODS

The medical records of patients who underwent combined injection-recession treatment from January 2019 to January 2020 for CI-IXT were reviewed retrospectively along with a group of age-matched controls with IXT without CI who underwent only unilateral LR recession during the same period. The following data were extracted from the record: age at surgery, average follow-up period, angle of deviation at distance and near and the difference between them before and after surgical procedure, correction of near and distance deviations, and recession dosage. Successful outcome was defined as a distance deviation in primary gaze between ≤10^Δ of exophoria/tropia and ≤5^Δ of esophoria/tropia.

RESULTS

A total of 10 patients and 20 controls were included. Average follow-up was 13.9 ± 3.67 months in the BPX group and 15.9 ± 3.61 months in the control group (P = 0.17). Postoperative distance deviation measured 8.30^Δ ± 5.88^Δ in the BPX group and 14.67^Δ ± 9.83^Δ in the control group (P = 0.80). Distance-near differences were significantly reduced in the CI-IXT group receiving BPX, by a mean of 6.60^Δ, from a preoperative mean of 10.50^Δ ± 3.65^Δ to 3.90^Δ ± 3.26^Δ (P < 0.01).

CONCLUSIONS

BPX injection combined with unilateral lateral rectus recession yields outcomes comparable to bilateral lateral rectus recession for distance deviations, and results in reduction of the distance-near difference in the angle of exotropia.

Comparison between Down Transposition and Slanted Surgery for Bilateral Lateral Rectus Recession in Convergence Insufficiency-Type Exotropia

Purpose: We compared bilateral lateral rectus recession with down transposition and slanted bilateral lateral rectus recession as surgical methods for convergence insufficiency-type exotropia.Methods: We included patients who underwent bilateral lateral rectus recession with down transposition or slanted bilateral lateral rectus recession for convergence insufficiency-type exotropia from January 2012 to January 2021 and observed them for more than 1 year. We retrospectively analyzed sex, age, preoperative best-corrected visual acuity, spherical equivalent, axial length, amount of surgery, and deviation angle before surgery and after surgery (immediately, 1 week, 6 months, and 1 year). We also examined surgical success and stereopsis before surgery and after 6 months and 1 year.Results: The down transposition group included 45 patients and the slanted group included 40. The deviation angle of distance, deviation angle of near and the near-distance disparity (NDD) all decreased in the down transposition group and slanted group 1 year after surgery (1.96 ± 8.77 prism diopter [PD] and 4.60 ± 4.99 PD, respectively; 5.53 ± 9.09 PD and 9.03 ± 9.09 PD, respectively; and 3.58 ± 5.26 PD and 4.43 ± 5.32 PD, respectively). Surgical success after 1 year was 55.6% in the down transposition group and 52.5% in the slanted group, and there was no significant difference between the two groups.Conclusions: In convergence insufficiency-type exotropia, both bilateral lateral rectus recession with down transposition and slanted bilateral lateral rectus recession were effective to correct the deviation angle of near, distance, and NDD. Both are suitable primary surgical methods for convergence insufficiency-type exotropia.

Slanted recession on bilateral lateral rectus for the treatment of intermittent Exotropia with convergence insufficiency

Purpose

To evaluate the efficacy and safety of slanted bilateral lateral rectus recession (S-BLRc) for the treatment of convergence insufficiency-type intermittent exotropia (CI-IXT) in children and to probe the relationship of the slanted amount and surgical outcomes.

Methods

Retrospective study. Fifty-eight patients with CI-IXT, aged 4 to 10 years old, underwent S-BLRc procedures. According to the different slanted amount between the upper and lower poles of lateral rectus, all the patients were grouped: Group A (slanting 1 mm, n = 22), Group B (slanting 1.5 mm, n = 18) and Group C (slanting 2 mm, n = 18). The successful surgical outcome was defined as deviation in the primary position ranging from exotropia< 8^△ to esotropia< 5^△ both at near and at distant as well as the near-distance difference (NDD) < 5^△. We analyzed and compared the preoperative and postoperative data including deviations both at near and at distance, NDD, objective torsion, horizontal deviation at up and down gaze, lateral incomitance, binocular vision and surgical success rate among three groups.

Results

The average deviations were significantly decreased from − 37.1^△ ± 4.2^△ (−,exotropia) to − 1.4^△ ± 4.6^△ at near (P < 0.05) and from − 25.8^△ ± 3.7^△ to − 0.1 ± 4.1^△ at distance (P < 0.05). The postoperative NDD on average was significantly reduced from 10.0^△ to 1.8^△ in Group A (P < 0.05), from 11.2^△ to 0.8^△ in Group B (P < 0.05) and from 13.3^△ to 0.9^△ in Group C (P < 0.05). There was a significant difference in the mean corrections of NDD among the three groups (8.2^△ in group A, 10.3^△ in group B and 12.4^△ in group C respectively, P < 0,05). All the patients attained various improvement of stereopsis after surgery. None had torsional diplopia, A-V pattern and lateral incomitance after strabismic surgery. Totally, the surgical success rate was 89.7% in our series at the 6- to 8-month follow-up.

Conclusions

Slanted bilateral lateral rectus recession is an effective and safe procedure for the treatment of CI-IXT in children. S-BLRc can successfully collapse exotropia both at distance and at near, decrease NDD and benefit to gain binocular vision. The correction of NDD was associated with the slanted amount.