Comparison of Improvement Rates between Distance and Near Visual Acuity in Children with Unilateral Amblyopia

Hosung Jin; Seung Ah Chung

doi:10.3341/jkos.5015.56.9.1432

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Jin and Chung: Comparison of Improvement Rates between Distance and Near Visual Acuity in Children with Unilateral Amblyopia

Original Article

J Korean Ophthalmol Soc 5015;56(9):1432-1438.

Published online: 29 August 5015

DOI: https://doi.org/10.3341/jkos.5015.56.9.1432

Comparison of Improvement Rates between Distance and Near Visual Acuity in Children with Unilateral Amblyopia

Hosung Jin, 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

∗ This study was presented as a narration at the 110th Annual Meeting of the Korean Ophthalmological Society 2013.

Received 27 February 201511 May 2015 Accepted 1 July 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 compare the improvement rates of distance visual acuity (VA) with that of near VA in amblyopic eyes of children with unilateral amblyopia.

Methods

The medical records of children with unilateral amblyopia successfully treated with patching were reviewed. During subsequent visits for amblyopia treatment, subjects had best-corrected VA measured at 4 meters and 1/3 meters every 2 months. Duration of treatment to achieve equal VA between both eyes and improvement rates were compared between distance and near, and analyzed according to the cause and severity of amblyopia, or age.

Results

A total of 76 children with amblyopia due to anisometropia and/or strabismus started amblyopia treatment at a mean age of 5.8 years and were followed up during a mean period of 16.4 months. Baseline VA was better at near than at distance in 52 children (68.4%), and better at distance than at near in 4 (5.3%). The mean duration of treatment was 5.4 months at distance and 3.9 months at near. However, the improvement rate considering the amount of improvement of VA was faster at distance; 0.11 log MAR/month at distance, and 0.08 log MAR/month at near ( p = 0.016). The improvement rate differences between dis-tance and near did not differ based on the cause of amblyopia, or age, whereas in mild amblyopia the improvement rate of dis-tance VA was significantly faster than near. Additionally, children with better initial near VA tended to have a faster improvement rate of distance VA.

Conclusions

Although baseline VA was better at near than at distance in more patients, the improvement rate was faster at dis-tance than at near. Children with better initial near VA appeared to have a faster improvement rate of distance VA.

Keywords: Amblyopia, Distance visual acuity, Improvement rate, Near visual acuity

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Figure 1.

Improvement rate (change in log MAR VA/month) of distance (■) and near (◆) visual acuity in the amblyopic eye. (A) Improvement rate of all patients. (B) Improvement rate of subgroups divided by the severity of amblyopia. VA = visual acuity. ^* Paired t-test for the improvement rate between distance and near; ^† One-way analysis of variance (ANOVA) for the difference be-tween distance and near among subgroups.

Table 1.

Baseline characteristics of 76 children with unilateral amblyopia

Characteristic	Cause of amblyopia			Overall (n = 76)
Characteristic	Anisometropia (n = 53)	Strabismus (n = 12)	Combined (n = 11)	Overall (n = 76)
Gender (male:female)	27:26	7:5	5:6	39:37
Age at baseline (years)	5.8 ± 2.0	5.5 ± 3.0	6.2 ± 2.6	5.8 ± 2.3
	(2.7-11.8)	(3.0-12.2)	(3.3-11.9)	(2.7-12.2)
Follow-up (months)	17.3 ± 13.5	15.4 ± 13.3	13.0 ± 6.1	16.4 ± 6.7
Severity of amblyopia (severe:moderate	e:mild) 18:17:18	6:3:3	8:2:1	32:22:22
(34.0:32.1:34.0)	(50.0:25.0:25.0)	(72.7:18.2:9.1)	(42.1:29.0:29.0)
VA at baseline (log MAR)
Distance	0.34 ± 0.20	0.36 ± 0.16	0.49 ± 0.16	0.37 ± 0.19
Near	0.12 ± 0.29	0.11 ± 0.18	0.28 ± 0.26	0.15 ± 0.28
VA last visit (log MAR)
Distance	0.15 ± 0.28	0.16 ± 0.21	0.26 ± 0.29	0.17 ± 0.28
Near	0.09 ± 0.26	0.09 ± 0.26	0.14 ± 0.22	0.09 ± 0.24

Values are presented as mean ± SD or number (%).

VA at baseline = visual acuity in the amblyopic eye at baseline; VA last visit = visual acuity in the amblyopic eye at last visit.

Table 2.

Duration of treatment to achieve a visual acuity in the amblyopic eye equal to that of its fellow eye

No.		Duration of treatment (months)		Difference between D-N	p-value
No.		Distance VA	Near VA	Difference between D-N	p-value
Overall	76	5.4 ± 3.8	3.9 ± 2.9	1.4 ± 3.2	<0.001^*
Cause of amblyopia					0.920^†
Anisometropia	53	5.2 ± 3.8	3.8 ± 3.1	1.3 ± 3.1	0.003^*
Strabismus	12	5.3 ± 3.7	3.7 ± 1.6	1.6 ± 3.6	0.137^*
Combined	11	6.4 ± 3.7	4.7 ± 2.8	1.6 ± 3.4	0.146^*
Severity of amblyopia					0.010^†
Severe	32	7.8 ± 4.1	5.2 ± 3.6	2.6 ± 3.8	0.001^*
Moderate	22	4.6 ± 2.8	3.4 ± 2.2	1.3 ± 2.9	0.054^*
Mild	22	2.6 ± 0.9	2.7 ± 1.3	-0.9 ± 1.4	0.771^*
Age at baseline					0.098^†
<5 years	24	6.3 ± 3.7	3.9 ± 2.2	2.3 ± 3.7	0.005^*
5 to 7 years	33	4.6 ± 3.6	4.0 ± 2.8	0.5 ± 2.8	0.263^*
>7 years	19	5.6 ± 4.0	3.8 ± 3.9	1.8 ± 3.0	0.020^*
Type of refractive error in anisometropic amblyopia (n = 53)					0.147^†
Hyperopia	18	4.9 ± 3.5	3.8 ± 2.7	1.1 ± 3.1	0.051^*
Hyperopic astig.	5	6.7 ± 3.6	3.3 ± 1.3	3.5 ± 3.7	0.011^*
Myopia	16	6.1 ± 4.4	5.3 ± 4.2	0.8 ± 3.0	0.275^*
Myopic astig.	14	4.5 ± 3.6	3.2 ± 2.0	1.3 ± 3.1	0.116^*
Severity of anisometropia (n =53)					0.179^‡
≥4 D	10	7.8 ± 5.2	6.6 ± 4.9	1.2 ± 4.5	0.425^*
<4 D	43	4.6 ± 3.1	3.2 ± 2.1	1.3 ± 2.8	0.003^∗

Values are presented as mean ± SD.

VA = visual acuity; D-N = distance-near visual acuity; astig. = astigmatism; D = diopter.

^∗ Paired t-test for the duration between distance and near;

^† One-way analysis of variance (ANOVA) for the difference between distance and near among subgroups;

^‡ t-test for the difference between distance and near between two subgroups.

Table 3.

Improvement rate of distance and near visual acuity in the amblyopic eye

	No.	Improvement rate (change in log MAR VA/month)		Difference between D-N	p-value
	No.	Distance VA	Near VA	Difference between D-N	p-value
Overall	76	0.11 ± 0.08	0.08 ± 0.05	0.02 ± 0.09	0.016^*
Cause of amblyopia					0.432^†
Anisometropia	53	0.12 ± 0.08	0.09 ± 0.05	0.02 ± 0.09	0.056^*
Strabismus	12	0.12 ± 0.09	0.07 ± 0.03	0.05 ± 0.09	0.099^*
Combined	11	0.08 ± 0.05	0.07 ± 0.05	0.00 ± 0.06	0.939^*
Severity of amblyopia	0.046^†
Severe	32	0.08 ± 0.08	0.08 ± 0.06	0.00 ± 0.01	0.923^*
Moderate	22	0.12 ± 0.06	0.10 ± 0.05	0.02 ± 0.07	0.172^*
Mild	22	0.15 ± 0.07	0.09 ± 0.03	0.06 ± 0.07	0.001^*
Age at baseline					0.486^†*
<5 years	24	0.10 ± 0.10	0.09 ± 0.05	0.02 ± 0.10	0.405^*
5 to 7 years	33	0.12 ± 0.07	0.08 ± 0.04	0.04 ± 0.07	0.004^*
>7 years	19	0.11 ± 0.07	0.09 ± 0.06	0.01 ± 0.09	0.643^*
Type of refractive error in anisometropic amblyopia (n = 53)					0.340^†
Hyperopia	18	0.12 ± 0.07	0.09 ± 0.05	0.03 ± 0.07	0.012^*
Hyperopic astig.	5	0.08 ± 0.06	0.09 ± 0.04	-0.01 ± 0.07	0.504^*
Myopia	16	0.11 ± 0.10	0.07 ± 0.06	0.04 ± 0.09	0.116^*
Myopic astig.	14	0.11 ± 0.07	0.09 ± 0.06	0.01 ± 0.10	0.592^*
Severity of anisometropia (n = 53)					0.986^‡
≥4 D	10	0.09 ± 0.09	0.06 ± 0.05	0.03 ± 0.08	0.391^*
<4 D	43	0.12 ± 0.08	0.10 ± 0.05	0.02 ± 0.09	0.377^∗

Values are presented as mean ± SD.

VA = visual acuity; D-N = distance-near visual acuity; astig. = astigmatism.

^∗ Paired t-test for the improvement rate between distance and near;

^† One-way analysis of variance (ANOVA) for the difference between distance and near among subgroups;

^‡ t-test for the difference between distance and near between two subgroups.

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