Vision Screening Procedures: From Inspection to Referral

Why Vision Screening Matters

A five-year-old sits in the back of her kindergarten classroom, squinting at the whiteboard. She has never complained — because she has never known anything different. Children with impaired vision often are not aware of their impairment; they accept the imperfect image without question. It is up to the adults responsible for children's health care and education to assure that children have their vision screened on a regular basis.

Vision screening is a set of procedures performed by properly trained persons for the purpose of early identification of children who may have vision problems and referral to appropriate medical professionals for further evaluation. In Minnesota, vision screening serves multiple programs: Child and Teen Checkups (C&TC), Head Start, Early Childhood Screening, and school-based programs. The procedures in this manual were developed based on recommendations from a panel of Minnesota-based vision screening experts convened by the MDH Community and Family Health Division in 2015, drawing on national guidelines from the American Association of Pediatric Ophthalmology and Strabismus (AAPOS) and others.

External Inspection: The WIPL Method

Before any chart-based testing begins, every child receives a systematic external inspection of the eyes and surrounding tissue. This procedure applies to children from post-newborn through 20 years of age and requires no equipment — only a well-lit room free of distractions.

If the child wears glasses, they may be removed to give the screener an unobstructed view. The area around the eyes should be checked for swelling, discoloration, excessive tearing, or discharge. The screener then observes whether one eye appears to turn in, out, up, or down relative to the other. Eyes should hold steady without excessive movement (nystagmus) while gazing straight ahead, and any persistent head tilt should be noted.

The eyes themselves are checked using the acronym WIPL:

• **W — Whites**: The sclera should be a shade of white with no new discoloration or growths.
• **I — Iris**: The iris should be a complete circle, and both eyes should be the same color.
• **P — Pupil**: Pupils should be clear and dark with no cloudiness or white discoloration. They should be equal in size and circular in shape.
• **L — Lids and Lashes**: Lids in their natural open position should give a full view of the pupil, free of lumps (chalazia), redness, or discharge along the margin. Lashes should be present on top and bottom lids and should not turn inward to contact the eye.

A child passes if all parts of the eye appear normal. Any noted abnormality triggers a referral — and if a white pupil (leukocoria) is observed, an immediate referral to an ophthalmologist or optometrist is necessary. Signs of excessive redness or discharge mean the screening should be stopped entirely to reduce the risk of spreading a possible infection.

Visual Acuity Screening: Age-Specific Standards

Visual acuity — the sharpness or clarity of a person's vision — is expressed as a fraction. The numerator represents the screening distance in feet, and the denominator represents the smallest line on which the majority of optotypes (standardized letters or symbols) are correctly identified. For example, if a child's vision is 20/70, it means that at 20 feet away, the smallest line they can read is the 20/70 line — a line that a person with 20/20 vision could read from 70 feet away.

The American Academy of Pediatrics recommends visual acuity screening at 10 feet for all children. Results are recorded for each eye as 10/XX (20/XX). For children ages 3 through 5, screeners use LEA SYMBOLS® or HOTV wall charts with 50% spaced rectangle boxes around each line, along with a response card so children can point to matching shapes rather than naming them.

The procedure follows a consistent protocol: the right eye is screened first with the left eye occluded. Starting from the top line, the child identifies optotypes moving down until one is missed, then returns to the line above. To receive credit for a line with 5 optotypes, the child must correctly identify any 4 of 5.

Passing criteria are age-specific:

• **Age 3**: 10/25 (20/50) or better in each eye, without a two-line difference between eyes
• **Age 4**: 10/20 (20/40) or better in each eye, without a two-line difference between eyes
• **Age 5**: 10/16 (20/32) or better in each eye, without a two-line difference between eyes

A critical safety note: it is never recommended at any age to use a hand to cover the eye — children peek. The ability of a child to peek is impressive, even with constant vigilance. Peeking can cause a false negative, where a child passes when they actually cannot see properly. Specially constructed occluder glasses or adhesive patches must be used instead.

Key Takeaways

Effective vision screening depends on following standardized procedures consistently:

• **Start with external inspection** using the WIPL method (Whites, Iris, Pupil, Lids and Lashes) before any chart-based testing. A white pupil requires immediate referral.
• **Use proper occlusion** — never allow children to cover their own eyes with their hands. Kids peek, and false negatives put children at risk.
• **Apply age-specific passing criteria** for visual acuity: 10/25 at age 3, 10/20 at age 4, and 10/16 at age 5, always checking for a two-line difference between eyes.
• **Refer promptly** when abnormalities are detected. Children who resist having one eye covered should be suspected of having vision loss in the uncovered eye, rather than being labeled uncooperative.

Every child who passes through your screening station carries the possibility that you are the first person to catch a treatable condition. Impaired vision can contribute to the development of learning problems which may be prevented or alleviated through early identification and intervention.