Surgical Outcomes of Intermittent Exotropia According to the Constancy

Jae Hyung Lee; Nam Yeo Kang

doi:10.3341/jkos.2013.54.2.310

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Lee and Kang: Surgical Outcomes of Intermittent Exotropia According to the Constancy

Original Article

J Korean Ophthalmol Soc 2007;54(2):310-316.

Published online: 24 August 2007

DOI: https://doi.org/10.3341/jkos.2013.54.2.310

Surgical Outcomes of Intermittent Exotropia According to the Constancy

Jae Hyung Lee, MD, Nam Yeo Kang, MD

Department of Ophthalmology, Bucheon St. Mary's Hospital, The Catholic University of Korea, College of Medicine, Bucheon, Korea

Address reprint requests to Nam Yeo Kang, MD Department of Ophthalmology, The Catholic University of Korea, Bucheon St. Mary's Hospital #327 Sosa-ro, Wonmi-gu, Bucheon 420-717, Korea Tel: 82-32-340-2125, Fax: 82-32-340-2661, E-mail: nyeokang@catholic.ac.kr

Received 2 June 201215 October 2012 Accepted 2 January 2013

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

To investigate how the constancy of intermittent exotropia affects postoperative motor and sensory outcomes. Methods: A retrospective analysis was conducted of 44 patients with intermittent exotropia (IXT group) and 16 patients with constant exotropia with a previous history of intermittent exotropia (CXT group). All patients were followed up for more than 1 year postoperatively. Successful postoperative motor alignment was defined as within 8 prism diopters of exo- or esotropia at 6 meters and 33 centimeters. Successful sensory outcome (bifixation) was considered as stereoacuity ≤60 seconds of arc. The influence of constancy, age at surgery, duration of strabismus, preoperative gross stereopsis, preoperative distant deviation, and preoperative distant fusion to surgical outcomes were evaluated using logistic regression analysis.

Results

Mean age at surgery and follow-up periods was 9.34 years and 37.8 months in the IXT group, and 10.19 years and 45.7 months in the CXT group. Successful motor alignment rates of the IXT and CXT groups were 65.9% and 48.3%, respectively. Postoperative bifixation rates of the IXT and CXT groups were 70.5% and 12.5%, respectively. The IXT group showed significantly better successful sensory outcome (p = 0.000), but no significant difference in motor outcome (p = 0.121). Constancy and preoperative distant fusion were associated with post-operative bifixation in univariate regression analysis (p = 0.001, 0.025, respectively). However, only the constancy was strongly associated with successful sensory outcome in multivariate regression analysis with an odds ratio of 20.138 (p = 0.008).

Conclusions

Surgical correction of intermittent exotropia during the intermittent period showed better sensory outcome than in constant deviation period.

Keywords: Constancy, Constant exotropia, Intermittent exotropia, Sensory functions, Strabismus surgery

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Table 1.

Characteristics of patients

Constant Exotropia (n = 16)	Intermittent Exotropia (n = 44)	p-value
Sex (M/F)	5/11	18/26	0.496^†
Age at surgery in years (range)	10.19 ± 5.12 (4-23)	9.34 ± 6.42 (4-45)	0.351*
Duration of symptoms before surgery in years (range)	4.30 ± 4.38 (1-18)	2.63 ± 2.62 (1-14)	0.084*
F/U mons (range)	45.69 ± 32.85 (12-114)	37.77 ± 30.02 (12-121)	0.391*
Pre-op distant fusion (Distant W4D)			0.001^‡
-Fusion	0	18
-Non-fusion	16	26
Pre-op distant fixation			0.000^‡
-Bifixation (stereoacuity ≤ 60 seconds of arc)	0	22
-Monofixation (stereoacuity > 60 seconds of arc)	16	22
Gross stereopsis			0.004^‡
- ≤800 seconds of arc	12	44
- >800 seconds of arc	4	0
Surgery			0.058^†
- Bilat. LR rec.	10	19
- Unilat. rec. & res.	5	24
- Unilat. LR rec.	1	1
Classification			0.147^†
- Divergence excess	1	0
- Basic	15	41
- Convergence insufficiency	0	3

Values are presented as mean ± SD.

Pre-op = preoperative; Bilat. = bilateral; Unilat. = unilateral; rec. = recession; res. = resection; LR = lateral rectus muscle.

^* Mann-Whitney U test

^† Chi-square test

^‡ Fisher's exact test.

Table 2.

Changes of deviation by constancy of exotropia

	Constant Exotropia	Intermittent Exotropia	p-value*
Pre-op distant deviation (PD)	31.50 ± 9.75 (18-45)	25.11 ± 6.51 (10-40)	0.026
Post-op distant deviation (PD)	12.19 ± 11.81 (0-35)	6.16 ± 8.56 (0-25)	0.064
Pre-op near deviation (PD)	33.06 ± 10.38 (12-50)	27.11 ± 7.79 (11-40)	0.039
Post-op near deviation (PD)	11.94 ± 11.73 (0-35)	6.84 ± 9.91 (-10~33)	0.124

Values are presented as mean ± SD.

Pre-op = preoperative; post-op = postoperative; PD = prism diopters.

^* Mann-Whitney U test.

Table 3.

Postoperative outcomes by constancy of exotropia

	Constant Exotropia	Intermittent Exotropia	p-value*
Successful motor alignment (≤8 prism dipoters)	7/16 (43.8%)	29/44 (65.9%)	0.121
Bifixation (stereoacuity ≤ 60 seconds of arc)	2/16 (12.5%)	31/44 (70.5%)	0.000

^* Chi-square test.

Table 4.

Postoperative sensory outcome(stereoacuity ≤ 60 or > 60 seconds of arcs) using logistic regression analysis

Variable	Univariate Model		Multivariate Model
Variable	Significance	Value of beta coefficient	Significance	Value of beta coefficient
Type (constant or intermittent)	0.001	16.692	0.008	20.138
Age at surgery (≤7 years or >7 years)	0.672	1.253	0.814	1.169
Duration of strabismus (≤3 years or >3 years)	0.301	1.895	0.816	1.232
Gross streopsis (≤800 or >800 seconds of arc)	0.242	4.000	0.341	0.178
Pre-op exodeviation (≤30 or >30 prism diopters)	0.180	2.185	0.662	1.398
Pre-op distant fusion	0.025	4.237	0.393	1.843

Univariate = univariate regression analysis; Multivariate = multivariate regression analysis; Pre-op = preoperative.

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