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Vision 101: Optotype-Based Screening for Preschool-Aged Children

The National Center for Children’s Vision and Eye Health (NCCVEH) reports that up to 1 in 17 preschool-aged children, 1 in 5 Head Start children, and an estimated 1 in 4 school-aged children have an undetected and untreated vision disorder that can interfere with their ability to develop properly and perform optimally in school. Conducting vision screening within these age groups will detect amblyopia (wandering eye) and uncorrected amblyopia risk factors such as hyperopia (farsightedness), myopia (nearsightedness), astigmatism (imperfection in the curvature of the eye), and anisometropia (asymmetric vision).

As a result, NCCVEH recommends two options for screening children in this age group: optotype-based distance visual acuity screening and instrument-based screening. In this blog we will discuss optotype-based vision screening.

What is Optotype-Based Screening?

Optotype-based distance visual acuity screening is recommended for children and adolescents, beginning at 3 years old. It uses optotypes (i.e. letters, numbers, or figures) at a specified distance. When tested, children will identify the optotypes on the chart either verbally or with matching cards. The use of matching cards is not required, but it will improve screening outcomes in most preschool-aged children because the child does not need to verbally identify an optotype to demonstrate the ability to see it. Simply pointing to the correct symbol on the matching card is a valid response.

To assess the results of the screening, the child must be able to correctly identify (verbally or with the matching card) at least three of four optotypes (or four of five, depending on the testing format) with both the right and the left eye. The passing lines by age are: 20/50 for 3-year-olds and 20/40 for 4- to 5-year-olds.

Early detection of vision issues can lead to an effective intervention and help to restore proper vision. Remember that young children rarely complain when they can’t see well because to them, it’s normal. That’s why screening is so important.

The Formats of Optotypes

 The NCCVEH-approved optotypes and formats are:

  • Single-surrounded LEA SYMBOLS® or HOTV letters in flipcharts for a 5-foot screening distance
  • LEA SYMBOLS® or HOTV letters on full threshold eye charts for a 10-foot screening distance
  • LEA SYMBOLS® or HOTV letters presented as a single line surrounded by a rectangular crowding bar on all four sides for a 10-foot screening distance


For children 3 to 5 years old, the recommendation is to use LEA SYMBOLS® or HOTV letters as optotypes, as these are the only ones that currently meet best practice standards. Note that both variations are appropriate for dual language learners because the child can match the letters or symbols and does not need to identify them by name. Before you get started screening young children, make sure the child is familiar with the symbols or letters you plan to use (the Good-Lite 3D LEA SYMBOL® set is a good way to confirm).

To shop MacGill’s single-surrounded 5-foot flipcharts, click here.

To shop MacGill’s selection of 10-foot Threshold Screening Charts, click here.

Shop MacGill’s 10-foot single surrounded with crowded bar flipbooks here and matching cards here and here.

Shop MacGill’s illuminated cabinets click here.

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