External Examination

Technique:  Using a penlight or other light source, examine for abnormalities of the eyelids, lashes, orbits and surrounding tissue, cornea and iris.  The orbit has seven surrounding bones: maxillary, zygomatic, frontal, sphenoid, palantine, ethmoid, and lacrimal.

Concerns: Persistent tearing may indicate a blocked tear duct, glaucoma, infection or allergy.  Unilateral ptosis can adversely impact visual development even if the pupil is not covered, so a child with ptosis should be referred to the ophthalmologist.  With a bilateral ptosis, consideration should be given to neurologic evaluation in addition to ophthalmologic referral.

Reflex blinking

Definition:  Rapid blink of the eyelids occuring in response to corneal touch, irritation or dryness, stimulation of the conjunctiva or eyelid margin, bright light, and/or loud noise.

Eye motility, fixation and tracking, muscle balance

Purpose: Assess eye alignment and range of motion of the eyes.  There are six muscles controlling eye movement – inferior and superior oblique, inferior and superior rectus, medial and lateral rectus.

Technique: The alignment of the eyes should be checked looking straight ahead and then looking left and right, up and down.

Concerns: Lack of symmetric eye position while tracking.

Pupils

Pupil Size and Reaction to Light

Technique: Examine for equal size/symmetry of pupils, roundness, and dilation/constriction reaction to light in each eye.

Concerns: Small asymmetry of pupil size may be normal, however an asymmetry of more than 1 mm needs further evaluation.  Sluggish reaction to light may indicate retinal or optic nerve problems and also requires further evaluation.

Accomodation

Purpose: Pupil constriction is reflexively linked to turning in of the eyes to focus on near objects. The constriction creates increased lens curvature to help with focus on near objects.

TechniqueExamine for pupil constriction as child tracks an object moving into near focus, such as a toy moving toward the child’s nose.

Concerns: Lack of pupil constriction with near focus.

Red reflex (RR) examination

Review Article:  Red Reflex Examination in Neonates, Infants, and Children
AAP, Section on Ophthalmology, AAPOS, AAO, and AA OF CERTIFIED ORTHOPTISTS – Pediatrics 2008; 122: 1401-1404.

Purpose:  Assesses clarity of the visual axis (cornea, anterior chamber, and vitreous) and presence/absence of retinal abnormalities.

Technique: Perform the RR exam in a darkened room.  (A larger pupil size will increase the retinal reflection.) Using a direct ophthalmoscope held close to your eye and about 12-18 inches from the infant/child’s eyes, view each eye separately.  Individual red reflex should be bright reddish yellow.  The reflex may be light gray in darkly pigmented, brown-eyed individuals.  There should be no opacities or white spots within the area of the red reflex.

Concerns: Referral to an ophthalmologist is recommended if there is a white reflex, blunting or absence of the red reflex, or there is an opacity/dark spot(s) or white spot.

[Note: ‘See Red’ Card Fact sheet on red reflex testing outlining how to perform the red reflex examination and listing current pediatric vision screening guidelines ]

Simultaneous red reflex examination (Bruckner Test)

Purpose: Indirect assessment of eye alignment and presence significant asymmetry of refractive error between the two eyes.

Technique: Use the ophthalmoscope setting with a bright large light. Have the patient fixate on the light.  Viewing from about 3 feet away in a darkened room, simultaneously observe the red reflex of both eyes. The red reflexes should be equal in size, brightness and color.

Concerns: Asymmetry of the red reflex between eyes when observed simultaneously suggests misalignment (phoria or tropia) or unequal refractive error (anisometropia) and should be referred for further evaluation as there is a high likelihood an amblyogenic condition exists.  Leukocoria (white reflex) may result from a retinoblastoma or coloboma.

Cover Tests:

Purpose: This test is used to detect subtle strabismus, i.e. latent phorias.  The corneal light reflex may look symmetric in the presence of a small-angle strabismus.  If there is an obvious deviation on the corneal light reflex, there is no need to perform the cover-uncover test.

Cover-uncover test (also called the Unilateral cover test)

Technique: This test can be performed in children capable of prolonged fixation.  The eyes are observed for change in alignment when one eye is occluded by the examiner.  Have the child focus on a distant object (about 10 feet away).  Look at the corneal light reflection on both eyes.  Watch the right eye.  Cover the left eye while watching the right eye for any deviation (up, down, in or out).  Then remove the cover and watch the just uncovered eye for deviation and realignment.  Repeat watching the left eye while covering the right eye.  Repeat on each eye with child focusing on a near object.

Concerns: Shifting of an eye suggests strabismus.

Alternating cover test

Technique:  With the child focusing on distant object (10-20 feet away), cover the right eye.  While observing the right eye for deviation, move the cover away from the right eye and cover the left eye – keeping one eye occluded at all times. Repeat for the left eye.

Concerns: Deviation of an eye as the cover is removed.

Cross cover test

Technique: With the child looking at a distant object, cover the right eye and look for movement of the left eye occurring immediately after placing the cover on the right eye.  Then cover the left eye and look for movement of the right eye.  If there is no apparent misalignment of the eyes, move the cover from right eye to left eye to right eye repeatedly, waiting a few seconds between movements.

Concerns: If an eye shifts in or out as the cover is moved, a strabismus is present.

Corneal light reflex test (Hirschberg test)

Purpose: To assess ocular alignment; tests for medium- to large-angle strabismus.

Technique: Note the position of the corneal light reflection from a light held about 2-3 ft from the child’s eyes and near the examiner’s dominant eye.  With the child fixating on the light the reflection should be in the center of the cornea.  Look for reflection in the same location on the cornea of each eye, even when the eyes move.

Concerns: Displacement of the corneal light reflex in one eye suggests strabismus.

Vision assessment – Method depends on the child’s age and developmental status.

  • Infant through about two or three years of age  – test the ability to fix on an object, maintain fixation,  and follow objects visually into various gaze positions.  This should be done with each eye independently and with both eyes together.
  • 2 or 3 years of age until 5 years – Attempt formal visual acuity testing. In a cooperative patient, a visual acuity test can be successfully completed.  See Visual Acuity section for information on age-appropriate tests.  Assess each eye independently.
  • Ages 5 to 6 years and older – Use Snellen Letter or Number Charts or other age appropriate visual acuity test.  See Visual Acuity section for further information.  Assess each eye independently.

Visual acuity charts

Younger children have difficulty using a vision-testing machine.  It is advisable to have wall charts and picture cards available for vision testing.  A line of figures is preferred over single figure charts.  Be careful to obtain good coverage of the eye not being tested – no ability to peek.  Testing should be performed in a well-lit area at 10 feet, unless otherwise noted.  Children who wear corrective lenses should be tested with the lenses, unless the correction is for reading only.

Teller acuity cards
Teller Acuity Cards are the standard diagnostic tool for evaluating visual acuity in infants and non-verbal children and adults.  The cards test visual attention to each of a series of cards containing stripes of different widths (spatial frequencies).  The cards allow estimation of acuity in two to six minutes per eye and show high levels of accuracy and reliability.

Lea symbols [circle, square, house, apple (https://spie.org/Images/Graphics/Publications/FG04_P19-20_eyechart2.jpg)]
For patients 18 months and older.  Uses four symbols – circle, square, house and apple.  Can be used to screen special populations such as non-English speaking and non-verbal children.

HOTV
Useful for children who cannot yet name letters.  Child matches a letter (either H, O, T, or V) on a hand-held board to the letter the examiner points to on the wall chart.

Tumbling E
Presents a series of capital E letters with the cross-bars oriented in different directions.  The child indicates the direction of the cross-bars either with fingers or with a cut-out E shape.  Can be used by most children 3 and older.

Snellen Letter Chart  or Snellen Number Chart
Series of letters or numbers.  Can be used by most school-aged children.

Allen cards
This is a useful test for toddlers with some speech skills and can also be administered as a picture-matching test. The Allen chart utilizes seven simple, idealized pictures on flash cards – truck, house, horse, birthday cake, tree, telephone and bear.  This test is performed at a variable distance, starting at 2 to 3 feet from the cards and moving backwards 2-3 feet at a time until the child is unable to correctly identify the pictures.  The acuity score is calculated based on the furthest distance at which the child accurately identified the pictures.

Other
Patti Pics; Landolt C; House Apple Umbrella; Hand charts

Table-top Visual Acuity Instruments

Devices that simulate visual acuity chart testing without the 10-20 foot  vision screening space requirements.  Requires patient to view through the device lenses.   Often these instruments have the capacity to test other vision elements such as color vision and visual field.   Examples of commercially available instruments include:

  • Titmus Vision Screener
  • Topcon Screenoscope

Peripheral Visual Field Assessment

Purpose: Identify deficits in peripheral vision

Technique: Each eye should be tested for peripheral vision by quadrant.  Two examples of methods – In children able to count fingers,  the examiner holds arms out so hands are in different quadrants and quickly flashes a number of fingers of one hand.  This should be quick enough that the child cannot shift focus into the tested quadrant of vision.  Repeat, varying the quadrant and number of fingers flashed.  The child should identify number of fingers correctly in all quadrants.  Alternatively, with the infant or child focusing on your face, sneak a toy or bright object in from the outer edges of the peripheral fields (by quadrant) and watch for vision shift to focus on the object.

Concerns: The child does not respond to or identify the visual stimulus in each quadrant.

Ophthamoscopy/Retinal Exam

Purpose:Evaluation of the retina, optic nerve and macula

Technique:Need a direct ophthalmoscope. Use the examiner’s right eye to examine the patient’s right eye and the examiner’s left eye to examine the patient’s left eye.  Examine the optic disc – size, shape, color, and contour.  Examine the retina – vessel size, pulsation, presence of hemorrhage.  Examine the macula – pigmentation, contour.  To focus on the macula, ask the child to look at the light or use the target pattern and ask the child to look at the target.

Stereopsis

Purpose:To identify disturbed binocular vision due to strabismus or difference in refractive error between eyes.

Technique: There are two groups of tests to clinically measure binocular depth perception, or stereopsis – contour stereotests and random dot stereotests.

Concerns: A child who fails the test is at high risk for amblyopia and should have further evaluation.

Contour stereotests

E.g. Titmus Fly Stereotest

Random Dot stereotests

  • Random Dot E – for younger child.  A test plate of dots with the letter E rising out of it.
  • Random Dot Butterfly
  • Numerical
  • Various animals

Frisby Stereotest – A test that uses dots and a hidden cylinder shape.

Lang stereotest – A test that combines random dots and cylinder gratings.

Color Vision Tests

Purpose: Determine presence of color vision deficiency

Technique:  Many color vision tests are not child-friendly and may create false positive results.  Resources include:

Instrument-based Screening (Photoscreening and Autorefraction)

Purpose:  Instrument-based screening can provide information about sight-threatening conditions such as strabismus, refractive errors, cataract, and retinal abnormalities such as retinoblastoma.
Technique: Photoscrening uses optical images of the eye’s red reflex to estimate regractive error, medial opacity, ocular alignment and other factors such as ocular adnexal deformities (e.g. ptosis), all of which put a child at risk for developing amblyopia.

Autorefraction uses optically automated skiascopy methods or wavefront technology to evaluate the refractive error of each eye.  They typically measure one eye at a time, limiting their ability to detect strabismus in the absence of refractive error.involves evaluation of the red reflex in both pupils by examining a photograph produced by a calibrated camera under prescribed lighting conditions.  It requires a trained evaluator to examine the photographed papillary reflex.

Comments: Photoscreening and autorefraction offer hope in improving vision screening rates in preverbal children, preliterate children and children with developmental delays.  Children younger than 4 years can benefit from these technologies.  For children 4-5 years of age, photoscreening and autorefraction have not been shown to be inferior or superior to visual acuity testing with the use of vision charts.

[For further information, see: Instrument-Based Pediatric Vision Screening Policy Statement. Joint policy statement of the American Academy of Pediatrics, AAO, AAPOS and American Association of Certified Orthoptists.  Pediatrics 2012;130:983-986.]

Concerns: Must be performed and interpreted by trained evaluator.