Cochrane Amblyopia

The USPSTF recommends screening to detect amblyopia, strabismus, and defects in visual acuity in children younger than age 5 years. B recommendation. The USPSTF found no direct evidence that screening for visual impairment in children leads to improved visual acuity. However, the USPSTF found fair evidence that screening tests have reasonable accuracy in identifying strabismus, amblyopia, and refractive error in children with these conditions; that more intensive screening compared with usual screening leads to improved visual acuity; and that treatment of strabismus and amblyopia can improve visual acuity and reduce long-term amblyopia. The USPSTF found no evidence of harms for screening, judged the potential for harms to be small, and concluded that the benefi ts of screening are likely to outweigh any potential harms.( Calonge N, USPSTF. Screening for visual impairment in children younger than 5 years: Recommendation Statement. Ann Fam Med 2004;2:263-266.)

BACKGROUND: Amblyopia is a reversible deficit of vision that has to be treated within the sensitive period for visual development. Screening programmes have been set up to detect this largely asymptomatic condition and refer children for treatment while an improvement in vision is still possible. The value of such programmes and the optimum protocol for administering them remain controversial. OBJECTIVES: The objective of this review was to evaluate the effectiveness of vision screening in reducing the prevalence of amblyopia. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Group Trials Register, on The Cochrane Library Issue 2, 2005, MEDLINE (1966 to May 2005 week 1) and EMBASE (1980 to 2005 week 19). No language restrictions were placed on these searches. No handsearching was done. SELECTION CRITERIA: We planned to analyse data from randomised controlled trials and cluster-randomised trials comparing the prevalence of amblyopia in screened versus unscreened populations. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study abstracts identified by the electronic searches. Full text copies of appropriate studies were obtained and, where necessary, authors were contacted. No data were available for analysis and no meta-analysis was performed. MAIN RESULTS: Despite the large amount of literature available regarding vision screening no trials designed to compare the prevalence of amblyopia in screened versus unscreened populations were found. Data currently under preparation may be available for updates to the review. AUTHORS' CONCLUSIONS: The lack of data from randomised controlled trials makes it difficult to analyse the impact of existing screening programmes on the prevalence of amblyopia. The absence of such evidence cannot be taken to mean that vision screening is not beneficial; simply that this intervention has not yet been tested in robust trials. To facilitate such trials normative data on age-appropriate vision tests need to be available and a consensus reached regarding the definition of amblyopia. In addition, the consequences of living with untreated amblyopia have yet to be quantified and a cost-benefit analysis carried out.( Powell C, Porooshani H, Bohorquez MC, Richardson S. Screening for amblyopia in childhood. Cochrane Database Syst Rev 2005(3):CD005020.)

BACKGROUND: Amblyopia is reduced visual acuity in one or both eyes in the absence of any demonstrable abnormality of the visual pathway. It is not immediately resolved by the correction of refractive error. Strabismus develops in approximately 5% to 8% of the general population. The aim of treatment for amblyopia is to obtain the best possible level of vision in the amblyopic eye. Different treatment options were examined within the review. OBJECTIVES: By reviewing available evidence we wanted to establish the most effective treatment for strabismic amblyopia. In particular this review aimed to examine the impact of conventional occlusion therapy for strabismic amblyopia and analyse the role of partial occlusion and optical penalisation for strabismic amblyopia. SEARCH STRATEGY: We searched CENTRAL, MEDLINE, EMBASE and LILACS in October 2007. There were no language or date restrictions in the electronic searches for trials. SELECTION CRITERIA: We included randomised controlled trials (RCTs) for the treatment of strabismic amblyopia including participants of any age. DATA COLLECTION AND ANALYSIS: Two authors working independently extracted and entered data into Review Manager 4.2 using the double data entry facility to check for errors. MAIN RESULTS: We included two RCTs. The studies reported mean logMAR visual acuity achieved. Mean difference in visual acuity was calculated.When comparing conventional part-time occlusion (with any necessary glasses), PEDIG 2006 reported this treatment was more beneficial than glasses alone for strabismic amblyopia. Mean difference between groups was -0.18 (statistically significant 95% CI -0.32 to -0.04).Supplementing occlusion therapy with near activities may produce a better visual outcome compared to non-near activities after four weeks of treatment (PEDIG 2005). Mean difference between groups was -0.17 (95% CI -0.53 to 0.19). However, this data is from a pilot study and the full data set will be added to updates of the review when available. AUTHORS' CONCLUSIONS: Occlusion, whilst wearing necessary refractive correction, appears to be more effective than refractive correction alone in the treatment of strabismic amblyopia. Combining occlusion and refractive correction with near activities may be more effective than occlusion and refractive correction alone. Further study of the role of near activities is necessary before a more definitive conclusion can be made. Results of a full trial are expected within the coming year. No RCTs were found that assessed the role of either partial occlusion or optical penalisation to refractive correction for strabismic amblyopia.( Shotton K, Elliott S. Interventions for strabismic amblyopia. Cochrane Database Syst Rev 2008(2):CD006461.)

BACKGROUND: Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the clear passage of light, preventing clear formation of an image on the retina for example, cataract, ptosis (droopy eyelid). It is particularly severe and can be resistant to treatment and the visual prognosis is often poor. Stimulus deprivation amblyopia is rare and precise estimates of prevalence difficult to come by; it probably constitutes less than 3% of all cases of amblyopia. 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 patching of the better-seeing eye but regimes vary, treatment is difficult to execute and results are often disappointing. OBJECTIVES: The objectives of this review were to evaluate the effectiveness of occlusion treatment for SDA, determine the optimum treatment regime and factors that may affect outcome. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) on The Cochrane Library (2006, Issue 1), MEDLINE (1996 to April 2006), EMBASE (1980 to April 2006) and LILACS (Latin American and Caribbean Literature on Health Sciences) (to November 2004). There were no date or language restrictions. SELECTION CRITERIA: We aimed to include randomised and quasi-randomised controlled trials of subjects with unilateral SDA defined as worse than 0.2 LogMAR or equivalent. There were no restrictions with respect to age, gender, ethnicity, co-morbidities, medication use, and the number of participants. DATA COLLECTION AND ANALYSIS: Two 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 treatment for SDA is or which treatment regime produces the best results. There is a need for further study in this area.( Hatt S, Antonio-Santos A, Powell C, Vedula SS. Interventions for stimulus deprivation amblyopia. Cochrane Database Syst Rev 2006;3:CD005136.)

Shotton K, Powell C, Voros G, Hatt SR. Interventions for unilateral refractive amblyopia. Cochrane Database Syst Rev. 2008(4):CD005137. BACKGROUND: Unilateral refractive amblyopia is a common cause of reduced visual acuity in childhood, but optimal treatment is not well defined. This review examined the treatment effect from spectacles and conventional occlusion. OBJECTIVES: Evaluation of the evidence of the effectiveness of spectacles and or occlusion in the treatment of unilateral refractive amblyopia. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and LILACS. Relevant conference proceedings were manually searched. There were no date or language restrictions. The searches were last run on 7 July 2008. SELECTION CRITERIA: Randomised controlled trials of treatment for unilateral refractive amblyopia by spectacles, with or without occlusion were eligible. We included studies with participants of any age. DATA COLLECTION AND ANALYSIS: Two authors independently assessed abstracts identified by the searches. We obtained full text copies and contacted study authors where necessary. Eight trials were eligible for inclusion. Data were extracted from seven. No meta-analysis was performed. MAIN RESULTS: For all studies mean acuity (standard deviation (SD)) in the amblyopic eye post treatment is reported.Comparison: Spectacles only versus no treatment (Clarke 2003). Mean (SD) visual acuity: spectacles group 0.31 (0.17); no treatment group 0.42 (0.19). Mean difference (MD) between groups -0.11 (borderline statistical significance: 95% confidence interval (CI) -0.22 to 0.00).Comparison: Spectacles plus occlusion versus no treatment (Clarke 2003). Mean (SD) visual acuity: full treatment 0.22 (0.13); no treatment 0.42 (0.19). Mean difference between the groups -0.20 (statistically significant: 95% CI -0.30 to -0.10).Comparison: Spectacles plus occlusion versus spectacles only: Clarke 2003 MD -0.09 (borderline statistical significance 95% CI, -0.18 to 0.00); PEDIG 2005b; MD -0.15 (not statistically significant 95% CI -0.32 to 0.02); PEDIG 2006a; MD 0.01 (not statistically significant 95% CI -0.08 to 0.10).Comparison: Occlusion regimes. PEDIG 2003a: 2 hours versus 6 hours for moderate amblyopia: MD 0.01 (not statistically significant: 95% CI -0.06 to 0.08); PEDIG 2003b: 6 hours versus full-time for severe amblyopia: MD 0.03 (not statistically significant: 95% CI -0.08 to 0.14). Stewart 2007a: 6 hours versus full-time occlusion: MD -0.12 (not statistically significant: 95% CI -0.27 to 0.03) AUTHORS' CONCLUSIONS: In some cases of unilateral refractive amblyopia it appears that there is a treatment benefit from refractive correction alone. Where amblyopia persists there is some evidence that adding occlusion further improves vision. It remains unclear which treatment regimes are optimal for individual patients. The nature of any dose/response effect from occlusion still needs to be clarified.

	Alaska Blind Child Discovery
	A cooperative, charitable research project to vision screen every preschool Alaskan
		Evidence-Based Amblyopia
Home	The USPSTF recommends screening to detect amblyopia, strabismus, and defects in visual acuity in children younger than age 5 years. B recommendation. The USPSTF found no direct evidence that screening for visual impairment in children leads to improved visual acuity. However, the USPSTF found fair evidence that screening tests have reasonable accuracy in identifying strabismus, amblyopia, and refractive error in children with these conditions; that more intensive screening compared with usual screening leads to improved visual acuity; and that treatment of strabismus and amblyopia can improve visual acuity and reduce long-term amblyopia. The USPSTF found no evidence of harms for screening, judged the potential for harms to be small, and concluded that the benefi ts of screening are likely to outweigh any potential harms.( Calonge N, USPSTF. Screening for visual impairment in children younger than 5 years: Recommendation Statement. Ann Fam Med 2004;2:263-266.) BACKGROUND: Amblyopia is a reversible deficit of vision that has to be treated within the sensitive period for visual development. Screening programmes have been set up to detect this largely asymptomatic condition and refer children for treatment while an improvement in vision is still possible. The value of such programmes and the optimum protocol for administering them remain controversial. OBJECTIVES: The objective of this review was to evaluate the effectiveness of vision screening in reducing the prevalence of amblyopia. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Group Trials Register, on The Cochrane Library Issue 2, 2005, MEDLINE (1966 to May 2005 week 1) and EMBASE (1980 to 2005 week 19). No language restrictions were placed on these searches. No handsearching was done. SELECTION CRITERIA: We planned to analyse data from randomised controlled trials and cluster-randomised trials comparing the prevalence of amblyopia in screened versus unscreened populations. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study abstracts identified by the electronic searches. Full text copies of appropriate studies were obtained and, where necessary, authors were contacted. No data were available for analysis and no meta-analysis was performed. MAIN RESULTS: Despite the large amount of literature available regarding vision screening no trials designed to compare the prevalence of amblyopia in screened versus unscreened populations were found. Data currently under preparation may be available for updates to the review. AUTHORS' CONCLUSIONS: The lack of data from randomised controlled trials makes it difficult to analyse the impact of existing screening programmes on the prevalence of amblyopia. The absence of such evidence cannot be taken to mean that vision screening is not beneficial; simply that this intervention has not yet been tested in robust trials. To facilitate such trials normative data on age-appropriate vision tests need to be available and a consensus reached regarding the definition of amblyopia. In addition, the consequences of living with untreated amblyopia have yet to be quantified and a cost-benefit analysis carried out.( Powell C, Porooshani H, Bohorquez MC, Richardson S. Screening for amblyopia in childhood. Cochrane Database Syst Rev 2005(3):CD005020.) BACKGROUND: Amblyopia is reduced visual acuity in one or both eyes in the absence of any demonstrable abnormality of the visual pathway. It is not immediately resolved by the correction of refractive error. Strabismus develops in approximately 5% to 8% of the general population. The aim of treatment for amblyopia is to obtain the best possible level of vision in the amblyopic eye. Different treatment options were examined within the review. OBJECTIVES: By reviewing available evidence we wanted to establish the most effective treatment for strabismic amblyopia. In particular this review aimed to examine the impact of conventional occlusion therapy for strabismic amblyopia and analyse the role of partial occlusion and optical penalisation for strabismic amblyopia. SEARCH STRATEGY: We searched CENTRAL, MEDLINE, EMBASE and LILACS in October 2007. There were no language or date restrictions in the electronic searches for trials. SELECTION CRITERIA: We included randomised controlled trials (RCTs) for the treatment of strabismic amblyopia including participants of any age. DATA COLLECTION AND ANALYSIS: Two authors working independently extracted and entered data into Review Manager 4.2 using the double data entry facility to check for errors. MAIN RESULTS: We included two RCTs. The studies reported mean logMAR visual acuity achieved. Mean difference in visual acuity was calculated.When comparing conventional part-time occlusion (with any necessary glasses), PEDIG 2006 reported this treatment was more beneficial than glasses alone for strabismic amblyopia. Mean difference between groups was -0.18 (statistically significant 95% CI -0.32 to -0.04).Supplementing occlusion therapy with near activities may produce a better visual outcome compared to non-near activities after four weeks of treatment (PEDIG 2005). Mean difference between groups was -0.17 (95% CI -0.53 to 0.19). However, this data is from a pilot study and the full data set will be added to updates of the review when available. AUTHORS' CONCLUSIONS: Occlusion, whilst wearing necessary refractive correction, appears to be more effective than refractive correction alone in the treatment of strabismic amblyopia. Combining occlusion and refractive correction with near activities may be more effective than occlusion and refractive correction alone. Further study of the role of near activities is necessary before a more definitive conclusion can be made. Results of a full trial are expected within the coming year. No RCTs were found that assessed the role of either partial occlusion or optical penalisation to refractive correction for strabismic amblyopia.( Shotton K, Elliott S. Interventions for strabismic amblyopia. Cochrane Database Syst Rev 2008(2):CD006461.) BACKGROUND: Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the clear passage of light, preventing clear formation of an image on the retina for example, cataract, ptosis (droopy eyelid). It is particularly severe and can be resistant to treatment and the visual prognosis is often poor. Stimulus deprivation amblyopia is rare and precise estimates of prevalence difficult to come by; it probably constitutes less than 3% of all cases of amblyopia. 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 patching of the better-seeing eye but regimes vary, treatment is difficult to execute and results are often disappointing. OBJECTIVES: The objectives of this review were to evaluate the effectiveness of occlusion treatment for SDA, determine the optimum treatment regime and factors that may affect outcome. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) on The Cochrane Library (2006, Issue 1), MEDLINE (1996 to April 2006), EMBASE (1980 to April 2006) and LILACS (Latin American and Caribbean Literature on Health Sciences) (to November 2004). There were no date or language restrictions. SELECTION CRITERIA: We aimed to include randomised and quasi-randomised controlled trials of subjects with unilateral SDA defined as worse than 0.2 LogMAR or equivalent. There were no restrictions with respect to age, gender, ethnicity, co-morbidities, medication use, and the number of participants. DATA COLLECTION AND ANALYSIS: Two 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 treatment for SDA is or which treatment regime produces the best results. There is a need for further study in this area.( Hatt S, Antonio-Santos A, Powell C, Vedula SS. Interventions for stimulus deprivation amblyopia. Cochrane Database Syst Rev 2006;3:CD005136.) Shotton K, Powell C, Voros G, Hatt SR. Interventions for unilateral refractive amblyopia. Cochrane Database Syst Rev. 2008(4):CD005137. BACKGROUND: Unilateral refractive amblyopia is a common cause of reduced visual acuity in childhood, but optimal treatment is not well defined. This review examined the treatment effect from spectacles and conventional occlusion. OBJECTIVES: Evaluation of the evidence of the effectiveness of spectacles and or occlusion in the treatment of unilateral refractive amblyopia. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and LILACS. Relevant conference proceedings were manually searched. There were no date or language restrictions. The searches were last run on 7 July 2008. SELECTION CRITERIA: Randomised controlled trials of treatment for unilateral refractive amblyopia by spectacles, with or without occlusion were eligible. We included studies with participants of any age. DATA COLLECTION AND ANALYSIS: Two authors independently assessed abstracts identified by the searches. We obtained full text copies and contacted study authors where necessary. Eight trials were eligible for inclusion. Data were extracted from seven. No meta-analysis was performed. MAIN RESULTS: For all studies mean acuity (standard deviation (SD)) in the amblyopic eye post treatment is reported.Comparison: Spectacles only versus no treatment (Clarke 2003). Mean (SD) visual acuity: spectacles group 0.31 (0.17); no treatment group 0.42 (0.19). Mean difference (MD) between groups -0.11 (borderline statistical significance: 95% confidence interval (CI) -0.22 to 0.00).Comparison: Spectacles plus occlusion versus no treatment (Clarke 2003). Mean (SD) visual acuity: full treatment 0.22 (0.13); no treatment 0.42 (0.19). Mean difference between the groups -0.20 (statistically significant: 95% CI -0.30 to -0.10).Comparison: Spectacles plus occlusion versus spectacles only: Clarke 2003 MD -0.09 (borderline statistical significance 95% CI, -0.18 to 0.00); PEDIG 2005b; MD -0.15 (not statistically significant 95% CI -0.32 to 0.02); PEDIG 2006a; MD 0.01 (not statistically significant 95% CI -0.08 to 0.10).Comparison: Occlusion regimes. PEDIG 2003a: 2 hours versus 6 hours for moderate amblyopia: MD 0.01 (not statistically significant: 95% CI -0.06 to 0.08); PEDIG 2003b: 6 hours versus full-time for severe amblyopia: MD 0.03 (not statistically significant: 95% CI -0.08 to 0.14). Stewart 2007a: 6 hours versus full-time occlusion: MD -0.12 (not statistically significant: 95% CI -0.27 to 0.03) AUTHORS' CONCLUSIONS: In some cases of unilateral refractive amblyopia it appears that there is a treatment benefit from refractive correction alone. Where amblyopia persists there is some evidence that adding occlusion further improves vision. It remains unclear which treatment regimes are optimal for individual patients. The nature of any dose/response effect from occlusion still needs to be clarified.
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Evidence-Based Amblyopia