Delta Journal of Ophthalmology

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 21  |  Issue : 1  |  Page : 69--73

Comparative study of bilateral rectus hang-back recession versus unilateral recession-resection for management of large-angle basic intermittent exotropia in Egyptian children


Nermeen M Badawi 
 Depatement of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt

Correspondence Address:
Nermeen M Badawi
Compound Lake View, 90th Street, Villa 3/1, New Cairo, Cairo 11835
Egypt

Abstract

Purpose The aim of this study was to compare the efficacy of lateral rectus recession-medial rectus resection (R-R) and bilateral rectus recession (BLR) for the management of large-angle basic intermittent exotropia (IXT) in Egyptian children. Patients and methods One-hundred patients with basic IXT were included in the study. They were divided into two groups: group A underwent R-R, and group B underwent BLR. All patients were subjected to a complete ophthalmological examination, including measuring the angles of deviation at distant and near. They were followed up at 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively. Results At the end of the follow-up period, the R-R group showed a success rate of 62%, whereas the BLR group showed a success rate of 64%. The effect of both techniques was similar on the distant angle of deviation, which was 6.4±4.3 for group A and 4.0±6.9 for group B postoperatively. In addition, the postoperative near angle of deviation was 5.4±2.3 for group A and 3.0±8.2 for group B, with no statistically significant difference between the two groups (P>0.05). Conclusion The two surgical procedures were comparable in the management of large-angle basic IXT.



How to cite this article:
Badawi NM. Comparative study of bilateral rectus hang-back recession versus unilateral recession-resection for management of large-angle basic intermittent exotropia in Egyptian children.Delta J Ophthalmol 2020;21:69-73


How to cite this URL:
Badawi NM. Comparative study of bilateral rectus hang-back recession versus unilateral recession-resection for management of large-angle basic intermittent exotropia in Egyptian children. Delta J Ophthalmol [serial online] 2020 [cited 2020 Oct 30 ];21:69-73
Available from: http://www.djo.eg.net/text.asp?2020/21/1/69/279725


Full Text



 Introduction



Intermittent exotropia (IXT) accounts for 40–90% of exotropias [1]. Most of the studies have focused on adults, and few have focused on certain types of exodeviations (intermittent, consecutive, sensory, etc.). In addition, they included a wide range of exodeviations [2],[3],[4],[5],[6], with the surgical table for large-angle XT being not yet established [7].

Performing a two-muscle surgery to correct large-angle IXT might save other recti for future procedures, which is a privilege in children [3]. It has a success rate ranging between 33 and 83% [8],[9],[10],[11],[12],[13].

In this study, bilateral rectus recession (BLR) and unilateral lateral rectus recession-medial rectus resection (R-R) were compared for management of large-angle basic IXT.

 Patients and methods



The procedures followed were conducted in accordance with the tenets of the declaration of Helsinki and were approved by the Ethical Committee of the Faculty of Medicine, Menoufia University. Before surgeries, all legal guardians of the patients were informed about the expected complications of surgery. All of them signed a written informed consent matching the Helsinki Declaration to participate in the study and for publication of data before enrollment in the study.

One-hundred consecutive patients with large-angle intermittent basic exotropia (IXT) more than or equal to 40 prism diopters (PD), fitting the inclusion criteria, were included in this prospective study. They were divided into two groups: group A (BLR) and group B (unilateral recession of lateral rectus and resection of medial rectus).

All patients were subjected to complete ophthalmic examination and a full cycloplegic refraction. Anisometropia was defined when there was a between-eyes spherical or cylindrical difference more than 1.5 D. Stereoacuity evaluation was performed using Titmus stereoacuity test (Stereo Optical Co. Inc., Chicago, Illinois, USA) at 33 cm and was defined as good stereopsis with a record less than or equal to 100 of seconds of arc. All values were converted from stereoacuity seconds of arc to logarithm of second of arc (log arc sec) to facilitate statistical analysis. Visual acuity (VA) and best-corrected VA were examined using the illiterate E VA chart.

Amblyopia was diagnosed when there was a between-eyes difference of more than two lines of VA or when the best-corrected VA was less than 20/30. In this case, part-time alternate occlusion with spectacles was prescribed for at least a month.

An alternate prism cover test with accommodative target was used to measure deviations in the nine positions of gaze, for distance at 6 m (D) and near at 33 cm (N) without (S) and with (C) best optical correction. Deviation was classified as basic intermittent XT when the difference between the distance and near angle was within 10 PD.

The control of exodeviation was examined by cover test at distance. It was classified as good (patient regain fusion without blinking or re-fusion), fair (patient needs to blink or re-fixate), and poor (does not spontaneously regain alignment despite blinking or re-fixation).

Duction and version movements were examined. Lateral gaze incomitance was defined with more than 10 PD change from the primary position. Ocular movement limitations were scaled on a five-unit scale from 0 to 4, where 0 represents full or 100% abduction or adduction and four represents a failure to abduct or adduct beyond the midline.

Ocular dominance was tested using the 10 prism base-down test.

Exclusion criteria were other forms of exotropia (restrictive, paralytic, etc.), previous surgeries, abnormal head posture (AHP), oblique muscle dysfunction, patterns (A,V, etc.), nystagmus, ocular structural abnormalities, neurological abnormalities, and developmental delays.

All operations were performed under general anesthesia by using the operating microscope. Patients with a dominant eye underwent unilateral medial rectus resection-lateral rectus recession of the nondominant eye according to the surgical dose in [Table 1]. Patients without eye dominance underwent BLR according to the surgical dose in [Table 2].{Table 1}{Table 2}

Follow-up visits were conducted at 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively. VA was determined by the illiterate E chart. AHP and angle of deviation (for distance and near) were measured. Satisfaction was defined as less than or equal to 10 PD of exotropia (XT) or esotropia (ET). In addition, ocular motility was assessed during the follow-up examinations. Rates of reoperation for residual XT or consecutive ET were recorded. Reoperation was performed when the angle of deviation was more than 20 PD after 1 month of trials of non-surgical treatments like alternate patching and over-minus lenses.

Statistical analysis

It was done by the correlation t test, Mann–Whitney U test, Friedman test, and Fisher’s exact test. P values less than 0.05 were considered statistically significant.

 Results



The age of patients in group A ranged between 4.5 and 12.2 years (mean, 7.3±4.8 years), whereas in group B it ranged between 3.8 and 10.5 years (mean, 6.7±3.6 years), with a statistically insignificant difference (P>0.05 by Mann–Whitney test).

The preoperative angle of deviation at distance ranged between 40 and 55 PD (mean, 48.5±7.3 PD) in group A and between 40 and 50 PD (mean, 45.6±4.3 PD) in group B, with no statistically significant difference (P>0.05). For near, it ranged between 45 and 50 PD (mean, 49.3±5.8 PD) in group A and between 45 and 50 PD (mean, 47.3±5.2 PD) in group B, with also no statistically significant difference (P>0.05).

The mean time for the surgical procedure was 17.45±6.33 min in group A and 18.36±4.96 min in group B, with no statistically significant difference between the two groups.

The average values of the angle of deviation at distance at 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively are shown in [Table 3]. There was a statistically significant decrease of the angle in every postoperative visit in comparison with the preoperative one (Friedman test, P<0.001), whereas there were no statistically significant differences between both groups in each postoperative visit by the Mann–Whitney test.{Table 3}

Similar results were found regarding the average values of the angle of deviation at near at 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively ([Table 4]). There was a statistically significant decrease in the angle in every postoperative visit in comparison with the preoperative one (Friedman test, P<0.001), whereas there were no statistically significant differences between both groups in each postoperative visit by the Mann–Whitney test.{Table 4}

[Table 5] illustrates the postoperative outcome in the two groups.{Table 5}

The amounts of exo-drifting at the first day, 1 week, 1 month, 3 months, and 6 months postoperatively were 1.2±0.8, 1.8±0.9, 2.5±0.7, 3.4±2.2, and 3.5±3.9, respectively, in group A and 3.9±2.8, 2.1±2.5, 1.1±2.1, 0.9±2.8 and 1.1±3.1, respectively, in group B, with a statistically significant difference between the two groups at the first day and first week (P<0.05), with more exo-drifting in group B. There was no statistically significant difference between the two groups at 1 and 3 months postoperatively. However, after 6 months, group A showed more statistically significant exo-drifting than group B.

The lateral gaze incomitance was found in 12 (24%) patients in group A and in seven (14%) patients in group B at the first postoperative visit, with a statistically significant difference (P<0.05). These results decreased to nonstatistically significant differences (P>0.05) by the first week to six (12%) and four (8%) patients, respectively. However, by the end of the first month, all cases of lateral gaze incomitance were resolved.

The amount of limitation of abduction ranged between 0 and 4 (2.7±1.2) in group A at the first postoperative visit and between 0 and 3 (1.5±1.4) in group B, with a statistically significant difference (P<0.05). At the first week visit, the limitation of abduction in group A remained the same, whereas this of group B decreased to 1.1±1.0 (P<0.05). By the end of the first month, no limitation of abduction was detected in either group.

It was possible to examine stereoacuity in 56% (28) of patients in group A and 48% (24) in group B. Preoperatively, its logarithmic value ranged from 1.7 to 2.5 log arc sec (mean, 1.9±0.4) in group A and 1.7–2.6 (mean, 1.8±0.5) log arc sec in group B. By the end of the follow-up period, it ranged from 1.6–2.9 (mean, 2.0±0.7) log arc sec in group A and 1.8–2.8 (mean, 2.1±0.6) log arc sec in group B, with no statistically significant difference (>0.05).

There were no reported cases of limitation of movement, AHP, and A or V patterns in either group. Two cases of re-operation were reported in the R-R group for consecutive ET more than 20 PD.

 Discussion



This study compared the surgical outcomes of either R-R or BLR procedures in the management of large-angle basic IXT (40–55 PD) in Egyptian children. Regarding the effect of both techniques on the distant and near angles of fixation, the study found that there was no statistically significant difference between the two techniques, which is similar to the results reported by Bang et al. [14], after a 5 year-study. On the contrary, Burian and Spivey [8] suggested that the BLR affected more the distant angle. So they favored the R-R technique. In the present study, during the early postoperative period (1 day and 1 week, postoperatively), the R-R group showed a statistically significant overcorrection than the BLR group, and this effect decreased over the following postoperative visits. These results were similar to those observed by Choi et al. [12]. This early ET effect (over-correction) was explained by Guyton [15],[16], who stated that the shortened medial rectus undergoes an early tethering effect followed by lengthening over time under the stimulation of sustained divergence resulting in gradual exotropic effect. This tethering effect of the resected medial rectus explains the statistically significant limitation of abduction faced in the R-R group in the early postoperative visits. In addition, it also explains why the R-R group showed a statistically significant less exo-drifting than the BLR group at early postoperative period tethering, whereas the lengthening of the medial rectus explains the steady increase of the exo-deviation angle by time in the R-R group. Similar results were found by Currie et al. [5] and Lee et al. [17]. On the contrary, Kim et al. [18] did not find any statistically significant exo-drifting differences between both groups. As for the stereoacuity, Kim et al. [18] encountered no statistically significant difference between the two groups regarding the changes of stereoacuity.

No complications were encountered in the present study. Similar results were found by Choi et al. [12], Bang et al. [14], and Lee et al. [17].

Regarding the long-term outcome and stability, some studies support the current study in the absence of any statistically significant difference between the two techniques, like the one conducted by Kim et al. [18] after a period of 2 years of follow-up and Bang and colleagues after a longer follow-up period of 5 years. However, Choi et al. [12] and Lee et al. [17] after a 2-year follow-up period concluded that BLR has a more favorable outcome owing to lower recurrence rates. On the contrary, Wang et al. [19] chose the recession-resection technique to be more effective than the BLR owing to significantly lower under-correction rates after a 15-month follow-up period.

 Conclusion



Both techniques (R-R and BLR) were equally effective in management of large-angle basic IXT as well as in their effect on both the distant and near angles of deviations.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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