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Interventions for stimulus deprivation amblyopia

  • Review
  • Intervention

Authors


Abstract

Background

Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the passage of light, preventing clear formation of an image on the retina (e.g. cataract, ptosis). It is particularly severe and can be resistant to treatment, leading to poor visual prognosis. Precise estimates of SDA prevalence are difficult to come by but it probably constitutes less than 3% of all amblyopia cases. In developed countries, most patients present under the age of one; in less developed parts of the world, presentation is likely to be significantly later than this. The mainstay of treatment is occlusion of the better-seeing eye, but regimens vary, can be difficult to execute and are traditionally believed to lead to disappointing results.

Objectives

The objectives of this review were to evaluate the effectiveness of occlusion treatment for SDA, to establish the optimum treatment regimen, to determine the factors that may affect outcome, and to identify realistic treatment goals.

Search methods

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) in The Cochrane Library (Issue 4, 2007), MEDLINE (1996 to November 2007), EMBASE (1980 to November 2007) and the Latin American and Caribbean Literature on Health Sciences (LILACS) (November 2007). The electronic databases were last searched on 27 November 2007. There were no date or language restrictions.

Selection criteria

Randomized and quasi-randomized controlled trials of participants with unilateral SDA, with visual acuity worse than 0.2 LogMAR or equivalent, were to be included. There were no restrictions with respect to age, gender, ethnicity, co-morbidities, medication use, and the number of participants.

Data collection and analysis

Two review authors independently assessed study abstracts identified by the electronic searches.

Main results

No trials were identified that met the inclusion criteria.

Authors' conclusions

It is not possible to conclude how effective SDA treatment is or which treatment regimen produces the best results. There is a need for further study in this area.

摘要

背景

遮蔽性弱視的治療

遮蔽性弱視是因為光線的傳遞路徑受到阻礙使得視網膜上無法形成清晰影像所造成(例如白內障,眼瞼下垂)。此種弱視特別嚴重,治療效果通常不佳,而導致視力預後很差。遮蔽性弱視的盛行率難以精確估計,可能大約占所有弱視患者中不到百分之三的比率。在已開發國家,大部分的病患皆在一歲以下即診斷;在較未開發的國家,可能就無法這麼早診斷出來。治療的主要方法是遮蓋好眼,但是方法各異,可能難以執行,而且傳統上一般認為可能會導致令人沮喪的結果。

目標

這篇回顧旨在評估遮眼治療用於遮蔽性弱視的效果,建立最理想的治療處方,找出影響治療結果的因素。

搜尋策略

我們搜尋了Cochrane圖書館內 Cochrane對照試驗之註冊中心(Central Register of Controlled Trials) (CENTRAL) (包括Cochrane 眼睛及視覺的試驗登記)(2007年第四期),MEDLINE(1996至2007年十一月),EMBASE(1980至2007年十一月),和拉丁美洲及加勒比健康醫學文獻(LILACS) (2007年十一月)。最後的電子資料庫搜尋日期是2007年十一月二十七日。沒有日期和語言的限制。

選擇標準

包含單側遮蔽性弱視且視力小於或等於LogMAR 0.2 的患者參與隨機或半隨機對照試驗。不設限於年齡,性別,種族,合併疾病,藥物使用,和參與者數目。

資料收集與分析

兩位作者分別評估由電子搜尋出來的研究摘要。

主要結論

沒有任何試驗符合我們的標準條件。

作者結論

目前對於遮蔽性弱視治療效果或最佳治療處方並無定論。未來還需要這方面更多的研究。

翻譯人

本摘要由高雄榮民總醫院畢勇賢翻譯。

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

幼年早期遮蔽性弱視的治療 一般會在兒童早期以遮蔽療法來治療因視覺被阻隔所引起的“懶惰眼”。“懶惰眼”一般是指弱視或視力不良卻無法以眼鏡矯正的眼睛。原因有很多。這篇回顧所評估的遮蔽性弱視起因於幼年早期視覺上的遮蔽,例如白內障(混濁水晶體)或垂瞼(眼瞼下垂)。遮蔽性弱視一般認為是所有弱視中最難治療的種類。弱視的盛行率約百分之一至五,而遮蔽性弱視只占其中不到百分之三。遮蔽性弱視的原因通常是因視覺被遮蔽引起,例如眼瞼下垂,白內障而非視力下降本身。患者通常在一歲以前表現出症狀。因此弱視的診斷必須在肇因治療後而且驗光度數矯正視力後才能確立。視力異常的程度各異;雖然典型遮蔽性弱視的視力喪失都很嚴重,但這篇回顧的操作是定義視力小於或等於LogMAR 0.2。弱視的治療目標在於增進視力恢復並防止影響好眼的視力。治療原理是將好眼遮蔽,強迫訓練使用弱視眼以刺激視力進步和增進立體感(雙眼視覺)。弱視若無經過良好治療,會影響以後成年工作的選擇。治療只在孩童早期有效。遮蔽好眼是目前主要的治療方法,遮蔽療法對父母造成麻煩,對孩子造成壓力,治療的時間從每天清醒時間算起至少要一小時。治療成功的報告也不一致。某些試驗認為早期治療效果較好,但未形成標準療法,也無法告訴我們最適當的治療時機。遮蔽療法對父母與孩子都會造成麻煩。本篇回顧旨在研究對於弱視最好的治療模式,我們搜集有關遮蔽療法的隨機對照研究,但沒有充分的結果可作結論。仍需要更佳品質的治療證據去。

Plain language summary

Treatment for amblyopia caused by obstructed vision in early childhood

Amblyopia or 'lazy eye' occurs when vision does not develop normally in early childhood. This may be due to strabismus, anisometropia (unequal refractive error) or obstruction of vision. Stimulus deprivation amblyopia (SDA), the type examined in this review, develops due to obstruction of vision in early childhood by conditions such as cataract (cloudy lens) or ptosis (droopy eyelid). Stimulus deprivation amblyopia is generally accepted to be the hardest type of amblyopia to treat. The prevalence of amblyopia varies from 1% to 5%, with SDA constituting less than 3% of all amblyopia cases. Health professionals or parents initially detect the accompanying signs of visual obstruction (e.g. leukocoria - whitish pupil associated with congenital cataract, droopy eyelid) when the patient is under the age of one. Amblyopia is then diagnosed after the causative factor has been treated and refractive correction has been given. The level of vision taken to be below normal varies; for this review, it was operationally defined as vision below 0.2 LogMAR or its equivalent, although typically the level of loss in SDA is much more severe. The aim of amblyopia treatment is to maximize visual recovery without adversely affecting the better-seeing eye. The rationale is to provide a good second eye should the better eye ever lose vision and to maximize stereopsis (binocular vision). Patching the better-seeing eye is the mainstay of treatment and amblyopia treatment is only effective in early childhood. Optimum treatment is unclear and prescribed regimens therefore vary. Reports of treatment success are inconsistent. Occlusion can be harrowing for parents and stressful for the child, making compliance an issue. Untreated or unsuccessfully treated amblyopia may affect employment in adult life. The aim of the review was to examine existing evidence to help establish realistic treatment outcomes and to determine the most effective treatment regimen(s). We searched for randomized controlled trials examining the effectiveness of patching or other treatment strategies for SDA, but did not find any that fulfilled our inclusion criteria. There remains a pressing need for better evidence of treatment effectiveness for this condition.

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