Changes in the interpupillary distance following general anesthesia in children with intermittent exotropia: a predictor of surgical outcomes

Change in the eye position under general anesthesia in children with intermittent exotropia

PURPOSE

To evaluate the eye position in subjects with intermittent exotropia and normal subjects under general anesthesia (GA) using the strabismus photo analyzer.

METHODS

This retrospective case-control study included 78 subjects with intermittent exotropia and 25 normal control subjects who underwent epiblepharon surgery. Eye position under GA was assessed using the strabismus photo analyzer, based on eye models generated from corneal lights and limbus in pre- and post-anesthesia images. Eye positions under GA in the control and intermittent exotropia groups were compared. Preoperative angle of deviation was also compared with amount of change in eye position under GA in the intermittent exotropia group.

RESULTS

Eye position under GA was more divergent in subjects with intermittent exotropia than in controls (P = 0.008). The amount of change in eye position under GA was correlated with the preoperative angle of deviation (r² = 0.47; P < 0.001). In small preoperative exodeviations, the change in eye position was primarily more divergent, whereas in large exodeviations, a convergent tendency-less exotropic compared with the preoperative angle of exodeviation-was observed.

CONCLUSIONS

In subjects with small preoperative exodeviations, there was a tendency for eye position to become more divergent after GA; in those with large exodeviations, there was less exotropia after GA.

Three Different Anesthesia Approaches in Blepharoptosis Surgery

Background

Despite the many methods of anesthesia for blepharoptosis, there is little documentation in the literature. When using the Müller aponeurosis composite flap advancement approach, one of the 3 anesthesia methods is chosen: general, local, and sedative anesthesia. On the other hand, the choice of anesthesia method is controversial.

Methods

A total of 101 patients (48 female and 53 male) admitted to hospital for treatment were selected: 38 (37.6%) patients (49 eyes) with local anesthesia, 34 (33.7%) patients (60 eyes) with general anesthesia, and 29 (28.7%) patients (42 eyes) with sedative anesthesia.

Results

The preoperative average marginal reflex distance (MRD1) in the local, general, and sedative anesthesia groups was 0.90, 0.35, and 0.47 mm, respectively. The corneal exposure area (CEA) in the local, general, and sedative approach groups was 63.2%, 57.8%, and 55.9%, respectively. The postoperative average distance for the MRD1 was significantly different among the 3 anesthesia approaches. The postoperative MRD1 in the local approach group was 3.28 mm and the CEA improved to 75.4%. In the general anesthesia approach group, the MRD1 was 3.01 mm and the CEA was 73.4%. In the sedative anesthesia approach group, the MRD1 and CEA were 3.62 mm and 74.0%, respectively. The MRD1 in the general, local, and sedative groups was 2.65 ± 1.48, 2.39 ± 1.65, and 3.17 ± 1.77, respectively; the difference was not significant (P > 0.05).

Conclusions

The general, local, and sedative anesthesia approaches are all effective in the correction of blepharoptosis; the results were similar regardless of the anesthesia approach. On the other hand, the patients felt more comfortable and surgeons could control the process more easily using the sedative approach.

Correlation between the Limbus-Insertion Distance of the Lateral Rectus Muscle and Lateral Rectus Recession Surgery in Intermittent Exotropia

The aim of this study was to investigate whether the limbus-insertion distance (LID) of the lateral rectus (LR) muscle can be a useful indicator for predicting the surgical effect of recession surgery in intermittent exotropia (IXT). Patients who underwent unilateral or bilateral LR recession for the basic type of IXT were included. The distance between the corneal limbus and the posterior edge of the insertion of LR muscle (limbus-insertion distance) was measured intraoperatively using surgical calipers (graded with 0.25 mm precision). We calculated the actual dose-response effect as the difference between the angle of preoperative deviation and the angle of postoperative deviation, and then divided the figure by the total amount of recession at postoperative months 1, 3, and 6. The correlation between the limbus-insertion distance (LID) of LR muscle and each dose-response effect was statistically analyzed. A total of 60 subjects were enrolled in this study. The mean LID of LR muscle was 5.8±0.7 mm. The dose-response effect was 3.2±1.0 prism diopters (PD)/mm at postoperative month 1, 3.4±1.0 PD/mm at postoperative month 3, and 3.4±1.1 PD/mm at postoperative month 6. The LID of the LR muscle was significantly correlated with dose-response effects in cases of unilateral and bilateral LR recession at postoperative months 3 and 6 (P = 0.01, <0.01, 0.04 and <0.01 respectively). As the LID of the LR muscle increased by 1 mm, the dose-response effect increased by 0.2PD/mm in unilateral LR recession, and by 0.4 PD/mm in bilateral LR recession at postoperative month 6. In conclusion, the LID of the LR muscle can be used as one predictor of the recession effect to assist in surgical planning for IXT. Moreover, undercorrection at the time of LR recession might be considered in patients with long LID of the LR muscle.

An external pilot study to test the feasibility of a randomised controlled trial comparing eye muscle surgery against active monitoring for childhood intermittent exotropia [X(T)]

INTRODUCTION

The evidence base for the treatment of strabismus (squint) is poor. Our main aim is to improve this evidence base for the treatment of a common type of childhood squint {intermittent exotropia, [X(T)]}. We conducted an external pilot study in order to inform the design and conduct of a future full randomised controlled trial (RCT).

METHODS

Children of between 6 months and 16 years with a recent diagnosis of X(T) were eligible for recruitment. Participants were recruited from secondary care at the ophthalmology departments at four UK NHS foundation trusts. Participants were randomised to either active monitoring or surgery. This report describes the findings of the Pilot Rehearsal Trial and Qualitative Study, and assesses the success against the objectives proposed.

RECRUITMENT AND RETENTION

The experience gained during the Pilot Rehearsal Trial demonstrates the ability to recruit and retain sites that are willing to randomise children to both trial arms, and for parents to agree to randomisation of their children to such a study. One child declined the group allocation. A total of 231 children were screened (expected 240), of whom 138 (60%) were eligible (expected 228: 95%) and 49 (35% of eligible) children were recruited (expected 144: 63% of eligible). Strategies that improved recruitment over the course of the trial are discussed, together with the reasons why fewer children were eligible for recruitment than initially anticipated. Attrition was low. Outcome data were obtained for 47 of 49 randomised children.

TRIAL PROCESSES AND DATA COLLECTION

The Trial Management processes proved effective. There were high levels of completion on all of the data collection forms. However, the feedback from the treatment orthoptists revealed that some modifications should be made to the length and frequency of the health service assessment and travel assessment questionnaires, thus reducing the burden on participants in the main trial. Modifications to the wording of the questions also need to be made.

MONITORING OF BIAS

Children who recruited to the trial were older and had more severe strabismus than those children eligible but declining participation. Strategies to account for this in a full trial are proposed.

REASONS FOR PARTICIPATION OR DECLINING STUDY

These were identified using qualitative interviews. The principal reasons for declining entry into the study were strong preferences for and against surgical treatment.

HARMS

There were no serious unexpected adverse events. Two children had overcorrection of their X(T) with reduction in binocular vision following surgery, which is in line with previous studies. No children in the active monitoring arm developed a constant strabismus although two showed some reduction in control.

CONCLUSIONS

The SamExo study has demonstrated that it is possible to recruit and retain participants to a randomised trial of surgery compared with active monitoring for X(T). For longer-term full RCTs, in order to maximise the generalisability of future studies, consideration needs to be given to planning more time and clinic appointments to assess eligibility and to allow consideration of participation; the greater use of research nurses for recruitment; and accommodating the strong preferences of some parents both for and against surgical intervention.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN44114892.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 39. See the NIHR Journals Library website for further project information.

Frontalis muscle flap advancement for correction of severe ptosis under general anesthesia: modified surgical design with 162 cases in China

BACKGROUND

Congenital blepharoptosis is a common pediatric disease. Frontalis muscle flap advancement is an effective surgical technique to treat patients with severe ptosis and poor levator function. However, since eye position changes under general anesthesia, it is necessary to adjust the position of the upper eyelid to achieve a better surgical outcome.

METHODS

A total of 162 children with severe congenital blepharoptosis underwent frontalis muscle flap advancement under general anesthesia. Patients were divided into two groups according to the different positions of eyelid suspension. The eyelid position of 82 children (96 eyes) in group A was adjusted to set at the superior limbus under general anesthesia, while the eyelid level of 80 children (94 eyes) in group B was adjusted according to the level labeled before anesthesia or the orthophoria level predicted using Krimsky's test. Lid level, ptosis recurrence, cosmetic appearance, and complications were evaluated 12 months after surgery.

RESULTS

Excellent functional and cosmetic results were achieved in 61 (63.5 %) children from group A and 85 (90.4 %) from group B. Fewer complications were observed in group B (36.5 vs. 9.6 %).

CONCLUSION

To achieve better surgical results after frontalis flap advancement for severe ptosis, it is necessary to adjust the eyelid level according to eye position changes that occur when the patient is under general anesthesia.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Determinants of ocular deviation in esotropic subjects under general anesthesia

PURPOSE

The authors attempted to identify the determinants of ocular deviation in a population of patients with esotropia under general anesthesia.

METHODS

Forty-one patients with esotropia were included. Horizontal ocular deviation was evaluated by the photographic Hirschberg test both in the awakened state and under general anesthesia before surgery. Changes in ocular deviation were measured and a multivariate analysis was used to assess its clinical determinants.

RESULTS

The mean age (± standard deviation [SD]) of study subjects was 13 ± 11 years and 51% were females. The mean spherical equivalent refraction of the right eye was 2.44 ± 2.50 diopters (D), with no significant difference between eyes (P = .26). The mean ocular deviation changed significantly, from 33.5 ± 12.5 prism diopters (PD) at preoperative examination to 8.8 ± 11.4 PD under general anesthesia (P = .0001). The changes in ocular deviation positively correlated with the pre-operative ocular deviation (correlation coefficient r = 0.59, P = .0001) and negatively correlated with patient age (correlation coefficient r = -0.53, P = .0001). These two determinants remained significant after multivariate adjustment of the following variables: preoperative ocular deviation; age; gender; spherical equivalent refraction; and number of previous strabismus surgeries (model r(2) = 0.49, P = .0001).

CONCLUSIONS

The ocular position under general anesthesia was reported as a key factor in the surgical treatment of subjects with esotropia; therefore, its clinical determinants were assessed. The authors observed that preoperative ocular deviation and patient age were the main factors that influenced the ocular position under general anesthesia.