Paediatric Eye Assessment
Vision assessment and eye examinations are important for detecting visual impairment in children. Impaired vision in children may cause issues with school performance, or may lead to blindness. Children with high risk of eye problems may be due to premature birth, history of congenital cataracts (clouding of the eye lens), metabolic or genetic diseases, and neurologic disorders should be assessed for visual defects. Therefore, careful assessment of the ocular system helps in identification and treating various visual defects in children.
Timing of eye assessment
In infants, usually eyes are assessed immediately after birth and continually at all routine supervision visits. All infants should be evaluated by the age of 6 months for ocular alignment, presence of an eye disease, and eye fixation. The infants’ eyes should be checked till the age of 3 or 4 years until the visual acuity measurement (vision screening) can be performed.
Eye assessment procedures
Your physician will examine the eyes based on the age of your child.
Eye assessment tests for children include:
Eyelids and orbit evaluation
Your doctor will evaluate the symmetry and function of the eyelids and orbits (bony cavities occupied by eyes and its muscles). If the orbit of one eye is disproportionate compared with the other, your doctor will further examine the eye for the presence of tumours, or abnormalities of the orbital bones.
Your doctor will evaluate the sclera (white part of the eye), conjunctiva (transparent tissue covering the sclera), cornea (transparent covering on the coloured part of eye), and iris (coloured part of the eye) externally with the help of a penlight. Your doctor will check the child’s eye for persistent discharge or tearing in the eyes.
The ocular alignment is evaluated in older infants as the young infants find it difficult to fix on a target and follow it. The ocular alignment tests are conducted to differentiate true strabismus (abnormal alignment of eyes) from pseudo strabismus (false appearance of crossed eyes).
These ocular motility tests include:
- Corneal light reflex test, it makes use of penlight to evaluate light reflection from the cornea. An off-centred reflex in an eye indicates proper eye muscle imbalance.
- In the cross-cover test, the child must look straight at the chart or a noise-making toy. After covering one eye, the movements of the uncovered eye are examined using an occluder (instrument which blocks light to one eye). Any type of inward or outward deviated movement indicates the presence of eye misalignment.
- Random dot E stereo test is used to evaluate depth perception with the help of cards. You doctor will ask the child to understand the letter ‘E’ on the model E card. After the child is allowed to wear stereo glasses, your doctor will randomly switch the cards side by side. Your child will have to identify the raised letter ‘E’ correctly from the stereo blank card in 4 of 6 attempts.
The eye pupils must be round, equal, and reactive to light. Slow reaction of the pupils may be due to retinal or optic nerve (transfers visual information from retina to brain) dysfunction. If the size of one pupil is larger than the other, or both pupils are larger than 1 mm, it indicates a serious neurologic disorder and requires further evaluation.
Red reflex test
The red reflex test can detect abnormalities in the back of the eye, and opacity in visual axis. This test is performed in a dark room to increase pupil dilation. Your doctor will focus the ophthalmoscope on each pupil at about 30 to 50 centimetres away from the eye and simultaneously view both the eyes. Bright reddish-yellow or light grey indicates the red reflex. Presence of white reflex, dark spots on the red reflex, dull red reflex, and lack of red reflex indicates need for further evaluation.
Additional tests for children aged 3 years and older include:
Visual acuity measurement (Vision Screening)
This test should be performed in children above 3 years of age; in case if the child doesn’t cooperate, another attempt should be tried after 4 to 6 months.
Snellen Acuity Chart
The child will be asked to read the lines on the chart and identify at least 4 of the 6 symbols on the line correctly. The lines on the chart can be moved to a critical level until the child identifies symbols correctly. This procedure is performed for each eye by covering the other eye at a time. Children with corrective eyeglasses should be screened wearing the eyeglasses.
Tumbling E or HOTV test
The tumbling E or HOTV test can be used for children who are unable to identify letters and numbers. This test consists of wall charts composed of tumbling Es or Hs, Os, Ts, and Vs. Your doctor will point a letter on the chart, and the child will be asked to identify the correct matches on the testing board.
Allen Cards or LH Symbols
These tests consist of flash cards with pictures on it, for example a house, cake, telephone, or horse. The children will be asked to identify these pictures before actual visual testing. In the Allen card test, the acuity score is calculated based on the distance at which the child can identify pictures correctly. In the LH symbols test, visual acuity is recorded based on the smallest size of the symbol identified by the child at 3 metres.
Your doctor will examine the optic nerve and retina by using an ophthalmoscope. Ophthalmoscopy is performed in children who are co-operative and able to fix their eyes on a toy.