Variability of Preoperative Angle of Deviation Measured on the Day of Surgery in Intermittent Exotropia

Eoi Jong Seo; Seung Ah Chung

doi:10.3341/jkos.2015.56.10.1591

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Seo and Chung: Variability of Preoperative Angle of Deviation Measured on the Day of Surgery in Intermittent Exotropia

Original Article

J Korean Ophthalmol Soc 2015;56(10):1591-1598.

Published online: 31 August 2015

DOI: https://doi.org/10.3341/jkos.2015.56.10.1591

Variability of Preoperative Angle of Deviation Measured on the Day of Surgery in Intermittent Exotropia

Eoi Jong Seo, M.D, Seung Ah Chung, M.D, PhD

Department of Ophthalmology, Ajou University School of Medicine, Suwon, Korea

Address reprint requests to Seung Ah Chung, MD, PhD Department of Ophthalmology, Ajou University Hospital, #164 World cup-ro, Yeongtong-gu, Suwon 16499, Korea Tel: 82-31-219-5257, Fax: 82-31-219-5259 E-mail: Mingming8@naver.com

Received 24 April 20152 June 2015 Accepted 14 August 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

To evaluate the characteristics and surgical outcomes of children with intermittent exotropia whose preoperative angle of deviation changed on the day of surgery.

Methods

The medical records of 323 children with intermittent exotropia who underwent lateral rectus recession in both eyes were reviewed. The records were classified according to the difference of 8 prism diopters (PD) or more between the largest an-gle of deviation measured within 3 months prior to the operation and that on the day of surgery into the increased, same, or de-creased groups. The frequency, characteristics, and surgical outcomes of each group were analyzed. The surgical amount was determined based on the largest angle of deviation measured at distance within 3 months before surgery.

Results

The angle of deviation at distance on the day of surgery was increased in 5 patients (1.5%) and decreased in 6 (1.9%). The near angle was increased in 19 (5.9%) and decreased in 22 (6.8%) patients. The groups in which distant deviation was changed had a greater distant angle and more patients with anisometropia. The group in which near deviation decreased was older than the same group and 81.8% of the patients were school-aged. In the group with changes in either distant or near devia-tion, the angle on the day of surgery changed toward decreasing disparity of near-distant deviation. On the last follow-up, the rate of overcorrection of 10 PD or more was 13.6% in the decreased near deviation group, which was significantly high ( p = 0.039).

Conclusions

The angle of deviation on the day of surgery could be different compared to the largest preoperative angle in some patients with intermittent exotropia. In patients with decreased near deviation, the rate of postoperative overcorrection might be high.

Keywords: Angle of deviation, Day of surgery, Intermittent exotropia, Surgical outcome

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Figure 1.

Bland-Altman plot for the change in angle of deviation on the day of surgery according to the largest preoperative angle (A) at distance ( p = 0.662, linear regression analysis) and (B) at near ( p < 0.001, linear regression analysis). PD = prism diopters.

Figure 2.

Bland-Altman plot for the change in angle of deviation on the day of surgery according to the preoperative disparity be-tween distant and near angle; (A) change in distant angle ( p = 0.046, linear regression analysis) and (B) change in near angle ( p < 0.041, linear regression analysis). PD = prism diopters.

Table 1.

Baseline characteristics of 323 children with intermittent exotropia

Basic characteristics	Values
Gender (male, %)	148 (45.8%)
Age of surgery (years)	7.3 ± 2.1 (3.1 to 13.2)
Preoperative follow-up (months)	7.9 ± 6.2 (3 to 39)
Postoperative follow-up (months)	10.1 ± 7.6 (6 to 38)
History of amblyopia	16 (5.0%)
Anisometropia	22 (6.8%)
Refractive error (SE, diopter)	-0.17 ± 1.63 (-5.50 to 4.75)
Type of intermittent exotropia (DE:Basic:CI)	12 (3.7%):258 (79.9%):53 (16.4%)
Control (good:fair:poor)	55 (17.0%):157 (48.6%):111 (34.4%)
Worth 4 dots (F/F:S/F:S/S) (n = 297)	54 (18.2%):112 (37.7%):131 (44.1%)
Values are presented as the mean ± SD (range) or number (%). SE = spherical equivalent; DE = divergence excess; CI = convergence insufficiency; F/F = fusion at distance/fusion at near; S/F = sup-pression at distance/fusion at near; S/S = suppression at distance/suppression at near.

Table 2.

Distribution of patients with the change in angle of deviation on the day of surgery compared to the largest pre-operative angle within prior to 3 months

	Decreased^*	Same^†	Increased^‡
Distance	6 (1.9)	312 (96.6)	5 (1.5)
Near	22 (6.8)	282 (87.3)	19 (5.9)

Values are presented as number (%).^* Cases in which exodeviation decreased by 8 PD or more on the day of surgery compared to the largest preoperative angle of devia-tion; ^† Cases in which the change was within 8 PD; ^‡ Cases in which exodeviation increased by 8 PD or more on the day of surgery com-pared to the largest preoperative angle of deviation.

Table 3.

Comparison of clinical characteristics based on the change in angle of deviation at distance

Basic characteristics	Decreased^* (n = 6)	Same^† (n = 312)	Increased^‡ (n = 5)	p-value
Gender (male, %)	3 (50.0)	142 (45.5)	3 (60.0)	0.795^§
Age of surgery (years)	5.9 ± 2.0	7.3 ± 2.1	7.8 ± 2.5	0.218^∏
Preoperative follow-up (months)	10.8 ± 13.8	7.9 ± 6.1	5.2 ± 2.4	0.320^∏
Angle of deviation (PD)
Distance	33.7 ± 6.4	26.6 ± 6.4	33.4 ± 14.4	0.003^∏
Near	28.0 ± 11.8	29.5 ± 7.3	38.4 ± 11.5	0.029^∏
Type of intermittent exotropia (DE:Basic:CI)	2:4:0	10:249:53	0:5:0	0.002^§
	(33.3:66.7:0.0)	(3.2:79.8:17.0)	(0.0:100.0:0.0)
Refractive error (SE, diopter)	0.71 ± 1.01	-0.17 ± 1.64	-0.88 ± 1.16	0.262^∏
History of amblyopia	1 (16.7)	15 (4.8)	0 (0.0)	0.364^§
Anisometropia	2 (33.3)	19 (6.1)	1 (20.0)	0.011^§
Control (good:fair:poor)	0:4:2	56:150:106	1:3:1	0.803^§
	(0.0:66.7:33.3)	(17.9:48.1:34.0)	(20.0:60.0:20.0)
Worth 4 dot (F/F:S/F:S/S) (n = 297)	0:1:4	53:109:126	1:2:1	0.494^§
	(0.0:20.0:80.0)	(18.4:37.8:43.8)	(25.0:50.0:25.0)

Values are presented as the mean ± SD or number (%). PD = prism diopters; DE = divergence excess; CI = convergence insufficiency; SE = spherical equivalent; F/F = fusion at distance/fusion at near; S/F = suppression at distance/fusion at near; S/S = suppression at distance/suppression at near. ^* Cases in which exodeviation decreased by 8 PD or more on the day of surgery compared to the largest preoperative angle of deviation; ^† Cases in which the change was within 8 PD; ^‡ Cases in which exodeviation increased by 8 PD or more on the day of surgery compared to the largest preoperative angle of deviation; ^§ p-value for chi-square test; ^∏ p-value for one-way ANOVA.

Table 4.

Comparison of clinical characteristics based on the change in angle of deviation at near

Basic characteristics	Decreased^* (n = 22)	Same^† (n = 282)	Increased^‡ (n = 19)	p-value
Gender (male, %)	11 (50.0)	124 (44.0)	13 (68.4)	0.108^§
Age of surgery (years)	8.0 ± 1.9	7.3 ± 2.1	6.4 ± 2.3	0.056^∏
Preoperative follow-up (months)	7.6 ± 6.9	7.8 ± 6.2	9.7 ± 5.8	0.396^∏
Angle of deviation (PD)
Distance	29.4 ± 8.8	26.4 ± 6.5	30.0 ± 6.1	0.013^∏
Near	35.6 ± 7.5	29.4 ± 7.3	26.5 ± 9.0	<0.001^∏
Type of intermittent exotropia (DE:basic:CI)	0:13:9	7:231:44	5:14:0	<0.001^§
	(0.0:59.0:41.0)	(2.5:81.9:15.6)	(26.3:73.7:0.0)
Refractive error (SE, diopter)	-0.56 ± 1.42	-0.16 ± 1.67	0.17 ± 1.07	0.347
History of amblyopia	0 (0.0)	16 (5.7)	0 (0.0)	0.294^§
Anisometropia	2 (9.1)	19 (6.7)	1 (5.3)	0.893^§
Control (good: fair: poor)	1:14:7	53:129:100	4:11:4	0.253^§
	(4.5:63.6:31.8)	(18.8:45.7:35.5)	(21.1:57.9:21.1)
Worth 4 dot (F/F:S/F:S/S) (n = 297)	4:9:8	44:98:118	6:5:5	0.318^§
	(19.0:42.9:38.1)	(16.9:37.7:45.4)	(37.5:31.3:31.3)

Values are presented as the mean ± SD or number (%). PD = prism diopters; DE = divergence excess; CI = convergence insufficiency; SE = spherical equivalent; F/F = fusion at distance/fusion at near; S/F = suppression at distance/fusion at near; S/S = suppression at distance/suppression at near. ^* Cases in which exodeviation decreased by 8 PD or more on the day of surgery compared to the largest preoperative angle of deviation; ^† Cases in which the change was within 8 PD; ‡ Cases in which exodeviation increased by 8 PD or more on the day of surgery compared to the largest preoperative angle of deviation; ^§ p-value for chi-square test; ^∏ p-value for one-way ANOVA.

Table 5.

Distribution of patients with the change in angle of deviation at near on day of surgery stratified by age of 6 years

	Decreased^* (n = 22)	Same^† (n = 282)	Increased^‡ (n = 19)	p-value^§
Age ≥ 6 years	18 (81.8)	194 (68.8)	8 (42.1)	0.019
Age < 6 years	4 (18.2)	88 (31.2)	11 (57.9)

Values are presented as number (%).^* Cases in which exodeviation decreased by 8 PD or more on the day of surgery compared to the largest preoperative angle of deviation; ^† Cases in which the change was within 8 PD; ^‡ Cases in which exodeviation increased by 8 PD or more on the day of surgery compared to the largest preoperative angle of deviation; ^§ p-value for chi-square test.

Table 6.

Surgical outcome at postoperative 6 weeks and at the last follow-up

	Decreased^*	Same^†	Increased^‡	p-value^§
At postoperative 6 weeks
Distance	n = 6	n = 308	n = 5	0.784
Success	5 (83.3)	271 (88.0)	5 (100.0)
Undercorrection	1 (16.7)	22 (7.1)	0 (0.0)
Overcorrection	0 (0.0)	15 (4.9)	0 (0.0)
Near	n = 22	n = 279	n = 18	0.595
Success	20 (90.9)	247 (88.5)	14 (77.8)
Undercorrection	1 (4.5)	19 (6.8)	3 (16.7)
Overcorrection	1 (4.5)	13 (4.7)	1 (5.6)
At the last follow-up
Distance	n = 6	n = 312	n = 5	0.868
Success	5 (83.3)	269 (86.2)	5 (100.0)
Undercorrection	1 (16.7)	32 (10.3)	0 (0.0)
Overcorrection	0 (0.0)	11 (3.5)	0 (0.0)
Near	n = 22	n = 282	n = 19	0.039
Success	19 (86.4)	244 (86.5)	16 (84.2)
Undercorrection	0 (0.0)	31 (11.0)	2 (10.5)
Overcorrection	3 (13.6)	7 (2.5)	1 (5.3)

Values are presented as number (%). ‘Success’ means the case showing between esodeviation of 8 PD or less without diplopia and exodeviation of 10 PD or less, ‘Undercorrection’ means the case showing exodeviation over 10 PD, and ‘Overcorrection’ means the case showing any esode-viation with diplopia or esodeviation over 8 PD. ^* Cases in which exodeviation decreased by 8 PD or more on the day of surgery compared to the largest preoperative angle of deviation; ^† Cases in which the change was within 8 PD; ^‡ Cases in which exodeviation increased by 8 PD or more on the day of surgery compared to the largest preoperative angle of deviation; ^§ p-value for chi-square test.

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