Ensuring your children have normal vision confirms that they will have comfortable reading and learning experiences. Many children who have frustration while reading are unable to articulate that their lack of attention may be due to uncomfortable vision. Screening and correcting for all potential vision issues in pediatric patients can vastly improve their school performance and can be life changing. Eye examinations can be done on children as young as 6 months old! However, if no immediate concerns are found by parents, a child's first eye exam is recommended to be done at age 1.
By far the most common finding in children is hyperopia, or more generally referred to as far-sightedness. While the term implies that you are able to see more clearly at distance, it does not necessarily mean that you are unable to see at near, only that it is more difficult. In consideration of treatment of hyperopia, the magnitude of the far-sightedness is of much more importance. In many children, the presence of hyperopia may not even require glasses or treatment. However, if the degree of hyperopia is quite large, you can not only have more difficulty seeing at near, but also at distance! Correcting a large amount far-sightedness in your child with reading glasses can positively affect their comfort while reading.
Exo and esophoria correspond to the binocularity of your child's eyes. All individuals have small variances in the alignment of their eyes. If the eyes are more outwards aligned, it is termed exophoria, and naturally inwards alignment is termed esophoria. Orthophoria would refer to an alignment that is straight. Many phorias are present in small amounts and do not require any treatment. If the magnitude of a phoria is high however, it can cause significant discomfort while reading or early fatigue when reading. Treatment of high phorias is usually done with prism in glasses or vision therapy.
Convergence insufficiency (CI) is perhaps the most common binocular vision issue in children. Our eye muscles function to shift our gaze at the target of interest. There are two types of extraocular muscle movement. These are versions and vergences. A version is an eye movement in which the eyes move in sync with one another to a specific direction. Up, down, left, right etc. A vergence is when the eyes move in a direction equal but opposite to one another. There are two types of vergences, convergence (moving the eyes inward together) to look at a nearer target, and divergence (moving the eyes both outward). As the term describes, convergence insufficiency is when the eyes are unable to both turn inward, or do so poorly. This is typically remedied with vision therapy. There are also other categories of convergence excess, divergence insufficiency, and divergence excess, however these are less common than CI and do not have as noticeable of an impact on school performance.
If one of the two eyes is misaligned in a direction that does not match the other, the eye is called strabismic. This is termed exotropia or esotropia depending on the direction of the misalignment. Strabismus has different forms, and the misalignment is graded by certain parameters. For example, the laterality, frequency, direction, magnitude are all important in determining what treatment is best. Laterality refers to which eye, which can be right, left, or alternating (both eyes take turns). Frequency refers to how often the eyes are misaligned, most are intermittent in nature (sometimes binocularity exists) but can also be constant (one eye is always misaligned). Direction refers to exo (outward) or eso (inward). And lastly the magnitude is expressed in prism diopters of how large the eye turn is. Strabismus is usually treated with vision therapy.
Amyblopia is a sensory condition that involves poor connection between an eye and the region of the brain that is responsible for its interpretation. This results in reduced vision in the affected eye. Ambylopia is generally referred to as "lazy eye". It is important to note that amblyopia is a sensory vision reduction, not one that can be fixed with a change in eye glass prescription or surgery. Improvement in vision is best achieved by allowing the affected eye to have dedicated visual exposure to improve brain communication with that eye. This involves combining most accurate prescription, patching therapy, and vision therapy.
There are certain factors that put your child at an elevated risk of developing ambylopia. These are called "amblyogenic factors" and are divided in Refractive Amblyopia and Strabismic Amblyopia. Refractive amblyopia is caused by one of the two eyes having a noticeably different prescription. This is usually when one eye is much more farsighted than the other, however very high amounts of near-sightedness or astigmatism can cause this as well. Strabismic ambylopia implies that due to a large misalignment of the eye, it does not get exposed to as much clear vision as is potentially possible and results in sensory vision reduction.
If ambylopia or a potential amblyogenic factor is not detected at a young age, it is very difficult to improve the vision with conventional methods. The best course of action is to have regular eye exams when younger to quickly treat the current vision reduction, or to avoid developing a lazy eye if an amblyogenic factor is detected. Children respond much better to treatment when younger because their brains have a higher level of plasticity, that is, they are continually making new neural connections within the brain. Adults are less able to respond to treatment due to more hardwired connections in the brain, but it can still be improved.