A new dose-response curve for bilateral medial rectus recessions for infantile esotropia.

PURPOSE: In 1982, Mims et al generated the first rigorous dose-response curve for bilateral medial rectus recessions for infantile esotropia (ET). Curve fitting calculations were hampered by substantial variability of surgical effect for the larger angles of ET, and an exponential curve was chosen for angles below 30 ET and a straight line for angles above 30 ET. In a continuing effort to improve the surgical success rate, a new series of results of 113 bilateral medial rectus recessions performed from 1990 to 1998 for infantile ET has been analyzed to produce a new dose-response curve and to study other potentially useful variables. METHODS: The amount of medial rectus recession performed in this series was the original dose-response curve from 1982, with conjunctival recessions performed for angles above 35 ET. RESULTS: The best curve that could be fitted to the effect versus millimeters of bilateral medial rectus recession was a single exponential curve. Other parameters explored with multivariate analysis, including head circumference, developmental delay, and intraoperative angles under anesthesia were not helpful in predicting effect of surgery at 6 weeks postoperative. A total of 87% were aligned at 6 months after surgery. Surgical failure at 6 months was more prevalent with larger preoperative angles (P =.0007) and with developmental delay (age when child first sat alone; P =.0078). CONCLUSION: Between 1982 and 1990, decreased variability of results of bilateral medial rectus recessions for larger angles of infantile ET enabled the generation of a single exponential dose-response curve for the entire range of angles of infantile ET.     

The medial rectus muscle insertion site in infantile esotropia

The distance from the corneoscleral limbus to the insertion site of the medial rectus muscle was measured at several stages of medial rectus recession surgery in 20 patients (40 eyes) with infantile esotropia. Disinsertion of the medial rectus muscle resulted in a mean reduction in the distance from the muscle insertion site to the corneoscleral limbus of 0.903 mm (P less than .001), whereas the use of fixation forceps on the insertion to abduct the eye resulted in an additional mean reduction of 0.306 mm (P less than .01). The strabismus surgeon often uses the muscle insertion site as a reference point in determining the desired location for recessing a muscle. Our results suggest that this method of measurement is unreliable in infantile esotropia because the position of the medial rectus muscle insertion site varies considerably during surgery.     

Large bimedial rectus recessions in congenital esotropia.

The success rate of large (6 and 7 mm) bimedial rectus recessions in 45 congenital esotropes with deviations of 50 prism dioptres or greater was found to be 91%. Judgment of final alignment was made six weeks postoperatively, with an average follow-up of 13 months. Large bimedial rectus recessions are an effective surgical treatment for congenital esotropia. This procedure does not significantly alter adduction, and leaves other muscles available should further surgery be necessary. These findings show that initial surgery on three or more muscles is unnecessary in congenital esotropia.     

Long-term results after bimedial posterior fixation sutures for infantile esotropia

Between 1984 and 1989, 79 patients were reexamined an average of 8 years after bimedial rectus muscle posterior fixation sutures. Patients who had to be operated additionally for vertical or cyclovertical motility disorders were excluded from the study. Seventy-five percent of the patients showed a residual deviation in the alternating prism and cover test of up to 5°. With Bagolini striated glasses 60 patients were found to have simultaneous perception at near and distance. The effects on convergence and lateral gaze were examined. After completed surgical therapy consecutive exotropia was found in 5% of all cases. In every 5th patient a reoperation was required. The study shows that bilateral posterior fixation suture of the medial rectus muscles leads to good long-term results in correcting infantile esotropia. Compared to other surgical techniques, significant advantage results from the low number of consecutive exotropias.     

Unilateral lateral rectus advancement with medial rectus recession vs bilateral medial rectus recession for consecutive esotropia

Background

To compare unilateral lateral rectus (LR) advancement with medial rectus (MR) recession with bilateral MR recession for patients with consecutive esotropia (ET)

Methods

Twenty-nine patients who developed consecutive ET of 30–35 PD following bilateral LR recession for intermittent exotropia were retrospectively reviewed. LR advancement into the original insertion site with 4.5 mm (30 PD ET) and 5.0 mm (35 PD ET) MR recession in the chiefly deviating eye was performed in 14 patients (A&R group). For 15 patients (BMR group), 4.5 and 5.0 mm bilateral MR recession was performed for 30 and 35 PD esodeviation respectively. As the primary outcome measure, postoperative ocular alignment between 5 PD of esophoria and 10 PD exophoria was considered a success.

Results

At 12 months postoperatively, successful surgical outcome was noticed in 12 patients (85.7 %) in the A&R group and 11 patients (73.3 %) in the BMR group. There was no statistically significant difference of final success rate between the A&R group and BMR group (p?=?0.411). At 12 months after surgery for consecutive ET, seven (50 %) and eight patients (53.3 %) acquired binocular fine stereopsis ≤100 s of arc in the A&R and BMR groups respectively

Conclusions

Advancement of the previously recessed LR with recession of the MR in the chiefly deviating eye has a high success rate comparable to that of bilateral MR recession, with the advantage of preserving one MR muscle for potential future intervention.     

双侧内直肌后徙治疗先天性内斜视

目的 观察2条内直肌后徒矫正先天性内斜视的效果。方法 术中采用2眼内直肌从角膜缘测量进行后徒的方法，后徒量（mm)等于从肌附着点后徒的距离加肌附着点至角膜缘的距离。结果 只用2条肌肉后徒矫正了平均82^△的内科。结论 对≤100^△的内斜视的矫正宜首先选择2条内直肌后徒。     

Lateral rectus resection versus medial rectus re-recession for residual esotropia: early results of a randomized clinical trial

PURPOSE: To compare lateral rectus muscle resection with medial rectus muscle re-recession for patients with residual esotropia. METHODS: This randomized controlled clinical trial included 25 patients (mean age, 18.8 +/- 8.7 years) with residual esotropia who were candidates for reoperation. They were randomly assigned into two groups: re-recession group (n = 12), in which the medial rectus muscle was recessed again, and the resection group (n = 13), in which lateral rectus muscle resection was performed. Postoperative deviation < or =10 prism dioptres was considered to be treatment success. RESULTS: The success rate of the re-recession group and the resection group was 67% and 54%, respectively; this difference was not statistically significant. Each 1 mm of medial rectus re-recession and lateral rectus resection corrected 7.5 +/- 1.2 and 2.5 +/- 0.5 prism dioptres of residual esotropia, respectively. In 50% of the re-recession group, mild medial rectus muscle underaction occurred; however, only 16.5% developed an increase in the near point of convergence. Major intraoperative and postoperative complications, including overcorrection and slippage or a lost muscle, did not occur in any of the patients. CONCLUSIONS: Medial rectus muscle re-recession can be a substitute for lateral rectus muscle resection in patients with residual esotropia. The resultant underaction of the medial rectus muscle after re-recession is relatively mild and causes no major problems.     

Decision analysis with Markov processes supports early surgery for large-angle infantile esotropia

PURPOSE: To assess tradeoffs in time spent with aligned visual axes or stereopsis and risked reoperations between three strategies for the treatment of large-angle infantile esotropia: first surgery at 6, 24, or 48 months of age. DESIGN: Decision analysis. METHODS: We simulated three hypothetic cohorts of children with this condition until their eighth year. Potential achievement of stereopsis, the diagnosis of dissociated vertical divergence or inferior oblique overaction, and various complications were modeled. Probability estimates were obtained from a comprehensive literature review. Analyses aimed to determine the strategy that was associated with longer time spent with aligned eyes and/or stereopsis and fewer reoperations. RESULTS: Eight-year-old children are expected to spend 72.6 vs 58.0 vs 37.8 months with aligned eyes and 26.8 vs 9.0 vs 1.5 months with stereopsis and to receive on average 1.76 vs 1.67 vs 1.46 surgeries, if they first underwent operation at 6 vs 24 vs 48 months, respectively. Children at 8 years are expected to have stereopsis at the rate of 36.1% vs 17.2% vs 5.1%, respectively. Operation at 6 months instead of 48 months is expected to yield an additional 9% of total follow-up time in health states with eye alignment and 11% in health states with stereopsis, per 5% increase in risk for extra operations (5% and 7%, respectively, per 5% increase in risk for operation at 6 vs 24 months). Wide-range sensitivity analyses and long-term projections point to the same direction. CONCLUSION: Given the benefit/risk tradeoffs, it is probably warranted to attempt to correct large-angle infantile esotropia as early as possible.     

Long-term postoperative stability in infantile esotropia

The purpose of this paper is to present the ocular motility status of a group of patients with infantile esotropia who underwent surgery before 2 years of age and were followed for a minimum period of 4 years until discharge from Ophthalmology and Orthoptic review. This retrospective review included 40 children with a diagnosis of infantile esotropia. There were 22 females and 18 males. The children were identified from surgical records between 1987 and 1992. Each child had surgery before the age of 2 years at an average age of 17 months (7 months to 22 months). Many patients (60%) achieved a small-angle (less than 20 prism dioptres), cosmetically acceptable strabismus. Nine patients (22.5%) achieved binocular vision postoperatively, five with microtropia, one with intermittent exotropia and three with bifoveal exophoria. The bifoveal patients did not exhibit high grade stereopsis, which may relate to the time of onset of infantile esotropia when development of cortical stereopsis is critical. Persistent amblyopia postoperatively was significantly associated with a poorer outcome and lack of binocular function.     

Long-term postoperative stability in infantile esotropia

The purpose of this paper is to present the ocular motility status of a group of patients with infantile esotropia who underwent surgery before 2 years of age and were followed for a minimum period of 4 years until discharge from Ophthalmology and Orthoptic review. This retrospective review included 40 children with a diagnosis of infantile esotropia. There were 22 females and 18 males. The children were identified from surgical records between 1987 and 1992. Each child had surgery before the age of 2 years at an average age of 17 months (7 months to 22 months). Many patients (60%) achieved a small-angle (less than 20 prism dioptres), cosmetically acceptable strabismus. Nine patients (22.5%) achieved binocular vision postoperatively, five with microtropia, one with intermittent exotropia and three with bifoveal exophoria. The bifoveal patients did not exhibit high grade stereopsis, which may relate to the time of onset of infantile esotropia when development of cortical stereopsis is critical. Persistent amblyopia postoperatively was significantly associated with a poorer outcome and lack of binocular function.