“Can my baby see? Is his vision normal for his age? How can you tell? How often should I have my baby seen?” These are some of the frequent questions that anxious new parents ask me in clinic. I will attempt to answer them in simple terms in order to provide the readers of BABY magazine enough useful information to guide them with their new role.
It is extremely important to remember that pediatric visual screening uses simple yet powerful techniques to detect ocular disorders at a young age when treatment is most effective. Unbeknownst to many parents, the developing visual system of infants and children can be permanently damaged by an abnormal visual image which may be caused by ocular misalignment (strabismus or squint), obstructed ocular media (lid ptosis, corneal opacity, cataract, and vitreous hemorrhage), high or unequal refractive error (anisometropia), or unsteady visual images (nystagmus). Significant ocular disease may often be missed, especially if only one eye is affected. Sometimes, vision-, as well as, life-threatening (retinoblastoma) disease may present with ocular signs.
When identifying visual abnormalities, it is important to understand the normal visual development. If you know what is normal for a child’s age, it would be easier to detect abnormal visual function. Visual acuity is expressed as a fraction. The top number refers to the distance you stand from the chart, usually 20 feet. The bottom number indicates the distance at which a person with normal eyesight could read the same line you correctly read. The less the bottom number in the visual acuity ratio, the better the acuity; and the greater the bottom number, the worse the acuity. Visual acuity at birth is quite poor, typically 20/1600, due to the immaturity of the central nervous system visual pathways and visual processing areas. Visual acuity improves to 20/100 by four months of age, and theoretically reaches nearly 20/20 by 12 months of age. A cooperative three year old should be able to demonstrate a visual acuity of 20/40, and a five year old 20/30. Many newborns show variable ocular alignment, with 70% showing exotropia (outward turning of eyes) and 30% having straight eyes. Esotropia (inward turning of eyes) is rare. By two or three months of age, most infants would have straight eyes. Misaligned eyes beyond three months of age require ophthalmic evaluation.
On more than one occasion, a general ophthalmologist will confess to seeing a parent distraught over the thought of not being able to improve the vision, despite proper spectacle correction, of his school aged child after having gone through an initial visual test at age ten or above! Abnormal visual development (amblyopia) is due to abnormal visual stimulation by blurred, misaligned, or unsteady visual image(s). It may be classified into several types, namely:
The treatment of amblyopia is step-wise in fashion. First, the obstruction in light entry is addressed. Ocular media is cleared by cataract surgery, corneal transplantation, etc. Once the media is clear, the image is focused with glasses, contact lenses, or occasionally intraocular lenses. Finally, ocular dominance is corrected by patching or blurring the better seeing eye.
A lot of parents inquire as to when they should bring in their baby for eye examination. We recommend that pediatricians, the front liners (!), screen at birth, six months, three years and five years of age. It is further recommended that children be subjected to an annual screening at school age until secondary school. An effective pediatric vision screening examination involves:
Ophthalmologists may be seen directly for this purpose.
Allow me to give you a brief overview of each of the four distinct components of an effective pediatric vision screening examination.
I hope this summary is clear and concise enough to be of use to our new parents out there! The benefit of early detection of eye disease, through early treatment with improved outcomes, far outweighs the mild hassle of pediatric vision screening. Go see your pediatrician and ophthalmologist today.