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Table 4 Methodological quality of the included studies

From: Effectiveness of screening preschool children for amblyopia: a systematic review

Reference

Prospective sample size planning

Blinding of outcome assessor

Comparability of groups

Consideration of confounding factors

Transparency of patient flow

Bray

1996 33

No*

Not specified

Not specified

Not specified

Yes||

Eibschitz-Tsimhoni

2000 27

No

Not specified

Not specified#

Not specified

No

82% of the originally recruited children were included in the analysis**

Rasmussen

2000 34

No

No

Not specified

No

Yes||

Williams

2002 31,32

No

Yes

Yes

Yes§

No

about 55% of the originally recruited children (equally distributed in both groups) were included in the analysis††

Williams

2003 28,29,30

No*

Yes

No

Yes§

No

only children who took part at the final assessment were presented and analysed (62% of the originally recruited children)

  1. * Retrospective power-analysis.
  2. Retrospective power-analysis for the outcome measure: visual acuity; prospective power-analysis for a not relevant endpoint.
  3. Parents of screened children were older, higher educated and smoked less during pregnancy; however, results were almost identical after adjustment for confounding factors.
  4. § For example: duration of breastfeeding, mother's educational level, 1st degree relative with squint, sex.
  5. || No children were excluded from the analysis.
  6. # It was only noted that the two communities were similar in terms of race, social status, health care facilities, education, nutrition and climate.
  7. ** Unclear, if only children who attended the final assessment were analysed.
  8. †† Only children who attended the final assessment were analysed.