Becker R H, Hübsch S H, Gräf M H, Kaufmann H
Department of Strabismology and Neuroophthalmology, University of Giessen, Giessen, Germany.
Strabismus. 2000 Sep;8(3):209-13.
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.
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.
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.
利娅符号对检测合作患者的弱视高度敏感。它们有利于儿童视力评估。因此，我们评估了利娅符号视力与年龄相关的正常值及双眼差异。
方法/患者：我们对199名年龄在21个月至7岁之间、于1999年1月至11月前来进行常规儿科检查的儿童中的50名进行了复查。测量了利娅符号视力（利娅符号单符号手册（LS）和利娅15行折叠距离视力表（CLS））以及兰多尔特C视力（单眼（LC）和视标间距为2.6'时的拥挤视力（LC(2.6)））。采用四选三标准。通过斜视和眼科检查排除斜视及任何器质性眼病，检查包括生物显微镜检查、检眼镜检查、视网膜检影或验光、遮盖试验或 Hirschberg 试验以及 Lang 立体视试验。
只有26%的家长（199名中的50名）同意在我院进行检查。在这50名儿童中，35名（32名）儿童能用单（拥挤）利娅符号分别测量双眼视力，而26名（25名）儿童能用单（拥挤）视标的兰多尔特C对双眼进行单眼检查。除一名3岁男孩外，所有30个月以上的儿童都能用单利娅符号进行检测。利娅视力超过兰多尔特视力。单视标和拥挤视标情况下，差异均约为1.5行（1.5 dB）。在能用单眼检测的儿童中，63%（69%）的儿童LS视力（CLS视力）高于0.8（0.63）。89%（83%）的儿童单（拥挤）利娅符号的双眼差异最大为1行。
能用利娅符号评估视力的最小儿童为23个月大。几乎所有30个月以上的儿童都能用利娅符号进行检测。利娅视力高于1且双眼差异小于2行则弱视可疑度较低。双眼差异超过1行的儿童应复查。
