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Preliminary report: examination of young children with Lea symbols
R H Becker1, S H Hübsch, M H Gräf
1Department of Strabismology and Neuroophthalmology, University of Giessen, Giessen, Germany.
Insights
Lea symbol visual acuity testing is effective for children over 30 months, with normal values established. An interocular difference of less than two lines suggests no amblyopia.
Area of Science:
- Ophthalmology
- Pediatric Optometry
Background:
- Lea symbols offer high sensitivity for amblyopia detection in cooperative children.
- They are suitable for assessing visual acuity in pediatric populations.
Purpose of the Study:
- To determine age-related normal values for Lea symbol visual acuity.
- To assess normal interocular differences in Lea symbol visual acuity.
Main Methods:
- Reexamined 50 children aged 21 months to 7 years undergoing routine pediatric examinations.
- Measured Lea symbol acuity (LS, CLS) and Landolt-C acuity (LC, LC(2.6)) using a three-out-of-four criterion.
- Excluded children with strabismus or organic eye disease through comprehensive orthoptic and ophthalmologic evaluations.
Main Results:
- Lea symbol acuity testing was successful in most children over 30 months.
- Lea acuity generally surpassed Landolt-C acuity by approximately 1.5 lines (1.5 dB).
- 89% (83%) of children exhibited an interocular difference of ≤1 line for single (crowded) Lea symbols.
Conclusions:
- Lea symbol visual acuity can be reliably assessed in children as young as 23 months.
- Lea acuity >1 with interocular difference <2 lines is not indicative of amblyopia.
- Children with interocular differences exceeding one line warrant reevaluation.
Background:
Lea symbols are highly sensitive for detection of amblyopia in cooperative patients. They are favorable for visual acuity assessment in childhood. Therefore, we assessed age-related normal values and interocular differences of Lea symbol visual acuity.
Methods/Patients:
We reexamined 50 out of 193 children aged 21 months to 7 years who came for a routine pediatric examination between January and November 1999. Lea symbol acuity (Lea Symbols Single Symbol Book (LS) and Lea 15-Line Folding Distance Chart (CLS)) and Landolt-C acuity (single (LC) and crowded with 2.6' inter-optotype distance (LC(2.6))) were measured. A three out of four criterion was used. Strabismus and any organic eye disease were excluded by orthoptic and ophthalmologic examination, consisting of biomicroscopy, ophthalmoscopy, retinoscopy or refractometry, cover test or Hirschberg test and Lang Stereotest.
Results:
Only 26% of the parents (50 out of 193) accepted an examination in our hospital. In 35 (32) of the 50 children, visual acuity could be measured in both eyes separately with single (crowded) Lea symbols, while 26 (25) children could be examined in both eyes monocularly with the Landolt-C with single (crowded) optotypes. Except for one 3-year-old boy, all of the children older than 30 months could be tested with single Lea symbols. Lea acuity surpassed Landolt acuity. The difference was about 1.5 lines (1.5 dB) for both the single and the crowded optotypes. In 63% (69%) of the children who could be tested monocularly, LS acuity (CLS acuity) was higher than 0.8 (0.63). 89% (83%) of the children had an interocular difference of maximum 1 line for single (crowded) Lea symbols.
Conclusions:
The youngest child whose visual acuity could be assessed with Lea symbols was 23 months old. Almost every child older than 30 months could be tested with Lea symbols. Lea acuity higher than 1 and an interocular difference less than 2 lines is not suspect for amblyopia. Children with a difference of more than one line should be reexamined.
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