The Clinical Features and Surgical Outcome of Premature Children with Exotropia

Kyung Tae Kim; Mi Young Choi

doi:10.3341/jkos.2015.56.2.241

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Kim and Choi: The Clinical Features and Surgical Outcome of Premature Children with Exotropia

Original Article

J Korean Ophthalmol Soc 2015;56(2):241-248.

Published online: 6 September 2015

DOI: https://doi.org/10.3341/jkos.2015.56.2.241

The Clinical Features and Surgical Outcome of Premature Children with Exotropia

Kyung Tae Kim, MD, Mi Young Choi, MD

Department of Ophthalmology, Chungbuk National University College of Medicine, Cheongju, Korea

Address reprint requests to Mi Young Choi, MD, Department of Ophthalmology, Chungbuk National University Hospital, 776 1 Sunhwan-ro, Seowon-gu, Cheongju 362-711, Korea, Tel: 82-43-269-6335, Fax: 82-43-264-5263 E-mail: mychoi@chungbuk.ac.kr

Received 26 April 201417 June 2014 Accepted 15 January 2015

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

We intended to investigate the clinical features and success rates of surgery in premature children with exotropia.

Methods

Twenty-two exotropia children with a gestational age of less than 37 weeks, or a birth weight of less than 2,000 g were included. The children had also been clinically observed for at least six months after surgery for exotropia. This study analyzed the results of their surgery in terms of gestational age, birth weight, ages at the first examination, and surgery, visual acuity, the angle of exodeviation at the first examination and the maximum angle of exodeviation before surgery, the frequency of accom-panied strabismus, and surgical results. Surgical success was defined as postoperative angle of deviation less than 10 PD. The patients were divided into success and failure groups, and a comparative analysis was performed between the 2 groups.

Results

The mean maximum angle of exodeviation before surgery was 28.4 ± 8.2 PD at far distance and 28.5 ± 8.3 PD at near distance. The mean angle of exodeviation at last visit after surgery was decreased to 8.0 ± 14.2 PD at far distance and 9.1 ± 14.8 PD at near distance. The success rate of surgery was measured to be 59.1% at the last visit. Recurrence was a major cause of failure, which occurred in eight cases (36.4%). The angle of exodeviation at the first examination and the maximum angle of exo-deviation in the failure group were higher than in the success group with statistical significance. The incidence of vertical strabismus before or after the surgery was 45.6% (10 cases) and there was no statistically significant difference between the 2 groups.

Conclusions

The premature children with exotropia had a relatively low surgical success rate and the major cause of the surgical failure was the recurrence of exotropia. The degree of the angle of deviation at the first examination and the maximum angle of exodeviation before surgery was an influential factor on the surgical results.

Keywords: Clinical feature, Exotropia, Premature children, Surgical outcome

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Figure 1.

Change of deviated angle during the follow-up after surgery in total patients.

Figure 2.

Change of angle of deviation during the follow-up after surgery in 3 groups. A: patients who maintained post-operative angle of deviation less than 10 prism diopter (PD) at last visit; B: patients of recurred exotropia at last visit; C: patients of consecutive esotropia at last visit.

Table 1.

Surgical outcome of exotropia according to retinopathy of prematurity

	Retinopathy of prematurity (n)
	(+)	(-)
Surgical success (n)	6	7
Surgical failure (n)	4	5

Fisher’s exact test, p = 0.639; (+): history of retinopathy of prematurity, (-): no history of retinopathy of prematurity.

Table 2.

Surgical outcome of exotropia according to operation for retinopathy of prematurity

	Operation for retinopathy of prematurity (n)
	(+)	(-)
Surgical success (n)	0	6
Surgical failure (n)	2	2

Fisher’s exact test, p = 0.133; (+): history of operation for retinopathy of prematurity, (-): no history of operation for retinopathy of prematurity.

Table 3.

Associated central nervous system abnormalities

Central nervous system abnormalities	Number of patients
Intraventricular hemorrhage	2
Germinal matrix hemorrhage	1
Cerebral palsy	3
Seizure	1
Encephalomalacia	1

Table 4.

The demographic and baseline characteristics of premature children with exotropia

	Patients (n = 22)
Sex (M:F) (n)	10:12
Gestational age (weeks, range)	31.6 ± 3.3 (25 to 36)
Birth weight (gram, range)	1516.3 ± 426.4 (690 to 2270)
Age of diagnosis (years, range)	3.8 ± 3.0 (1 to 12)
Age of surgery (years, range)	6.3 ± 2.4 (2 to 12)
Angle of exodeviation at first examination (PD, range)
Near	24.6 ± 9.0 (10 to 50)
Far	23.6 ± 9.2 (10 to 50)
Angle of exodeviation at operation (PD, range)
Near	28.5 ± 8.3 (12 to 50)
Far	28.4 ± 8.2 (15 to 50)
Follow-up (month, range)	24.0 ± 16.4 (6 to 48)
Vertical strabismus (n)	10
Retinopathy of prematurity (n)	10
Spontaneous regression	8
Cryotherapy	2
The type of refractive error (n)
Myopia	7
Emmetropia	23
Hyperopia	3
Astigmatism	11
Amblyopia (n)	5

Values are presented as mean ± SD unless otherwise indicated.

Table 5.

Comparison of preoperative and postoperative data between surgical success group and surgical failure group

	Surgical success group (n = 13)	Surgical failure group (n = 9)	p-value
Sex (M:F)	7:6	3:6	0.42^∗
Gestational age (weeks, range)	31.4 ± 2.8 (25 to 36)	31.8 ± 4.2 (25 to 36)	0.56^†
Birth weight (gram, range)	1491.5 ± 420.6 (690 to 2,100)	1552.0 ± 457.7 (882 to 2,270)	0.95^†
Age of diagnosis (years, range)	4.4 ± 3.7 (1 to 12)	2.9 ± 1.3 (1 to 4)	0.74^†
Age at surgery (years, range)	7.1 ± 2.3 (5 to 12)	5.1 ± 2.0 (2 to 9)	0.06^†
Follow-up (months, range)	22.2 ± 16.7 (6 to 48)	26.7 ± 16.5 (6 to 48)	0.56^†
Angle of exodeviation at first examination (PD, range)
Near	20.4 ± 4.8 (10 to 25)	30.6 ± 10.4 (15 to 50)	0.01^†
Far	19.2 ± 4.5 (10 to 25)	30.0 ± 10.6 (15 to 50)	0.01^†
Angle of exodeviation at operation (PD, range)
Near	25.4 ± 4.8 (15 to 30)	33.0 ± 10.4 (12 to 50)	0.02^†
Far	24.6 ± 4.3 (15 to 30)	33.9 ± 9.6 (20 to 50)	0.02^†
Postoperative angle of deviation at last visit (PD, range)
Near	3.1 ± 4.2 (0 to 10)	17.8 ± 20.2 (-30 to 40)	0.00^†
Far	2.6 ± 3.6 (0 to 10)	15.8 ± 19.9 (-30 to 40)	0.00^†
Vertical strabismus (n)	5	5	0.67^∗
Amblyopia (n)	2	3	0.61^∗

Values are presented as mean ± SD unless otherwise indicated.

^∗ Fisher’s exact test

^† Mann-Whitney U-test.

Table 6.

Comparison of degree of refractive errors between surgical success group and surgical failure group

	Surgical success group (diopter)	Surgical failure group (diopter)	p-value
Myopia	-0.71 ± 0.10	-0.75 ± 0.00	0.86^∗
Emmetropia	+1.26 ± 0.50	+1.17 ± 0.74	0.38^∗
Hyperopia	+3.50 ± 0.00	+4.50 ± 0.00	0.67^∗
Astigmatism	1.59 ± 0.38	1.95 ± 0.62	0.17^∗

Values are presented as mean ± SD.

^∗ Mann-Whitney U-test.

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