Pediatric Opthalmology

Lazy eye is a general term used by laypersons to describe a condition where one eye does not work as well as the fellow eye.  This may be due to an ocular misalignment where one eye does not point in the same direction as the other eye, medically termed as strabismus.  Another cause is amblyopia where one eye sees better as compared to the other eye despite correction with glasses.  
Normally, eye misalignment is common among newborns with resolution at around 6 months of age.  Beyond 6 months is considered abnormal and warrants a good eye examination.  Strabismus is the term for an ocular misalignment or a tendency towards misalignment.  Another term used by laypersons is squint since some patients tend to squint one eye under bright conditions.  The different terms to describe each misalignment are as follows:
Esotropia  - Inward deviation of eyes
Esophoria - Tendency of the eyes to drift inward
Exotropia - Outward deviation of eyes
Exophoria - Tendency of the eyes to drift outward
Hypertropia - One eye is higher than the other eye
Children with strabismus usually present with an obvious eye misalignment, squinting of one eye, or an unusual face turn or tilting the head to one side.   Those with a tendency towards misalignment manifest their misalignment during times of inattentiveness, upon waking up, during times of illness, or in some, when focusing either at distance or near.  Others present with subtle symptoms such as reading difficulty or problem in school.  Those who acquire strabismus after the age of 6 or 7 usually complain of double vision.  
The causes of strabismus vary.  It commonly occurs in infancy or childhood in which either the cause is unknown or due to a refractive error (near-, far-sighted or astigmatism).  Less often, it may be due to paralysis of an eye muscle or a restriction.  Paralysis of an eye muscle may be due to a viral illness or diabetes, trauma, or a brain problem which needs immediate neurologic work-up since the cause may be life-threatening.  Restriction on the other hand may be due to an inborn abnormality in the muscle, a long-standing strabismus, thyroid problem, trauma or previous surgery in the involved eye.  A blind eye or an eye with very poor vision also has the tendency to drift either inwards or outwards.
The priority in management of patients with eye misalignment is to look for the cause especially in patients with restrictions and paralysis.  Most of the time, just a careful history taking is enough to come up with a diagnosis.  Sometimes, a referral to a neurologist is necessary, as well as neuroimaging workup (CT-scan or MRI).  The patient is also evaluated for the need for glasses to see if the cause is refractive in nature.
Management of patients with strabismus always starts first with providing the best vision either with glasses and can be combined with patching for the treatment of amblyopia.  For those with cataracts or other eye abnormalities, treatment to improve or restore vision should be done first before treating the strabismus.  In patients where there is only a tendency towards misalignment, eye exercises may still work.  For some paralytic causes, a watch-and-wait approach may be all that’s needed since improvement or complete recovery is common.  Surgery is recommended to those who do not need or do not respond to the other forms of therapy.  How surgery works is the eye muscles are repositioned, strengthened or weakened depending on the type and degree of misalignment.  Despite surgery, the eyes may still have the tendency to drift, hence the need for regular follow-ups.
Amblyopia is a condition wherein one eye does not see as well as the other eye despite being given the best correction (glasses or contact lens). The reason for this is that the area of the brain that is responsible for processing what we see develops only after birth and is dependent on the clarity of vision. The first 3 months of life is the period where the brain develops the most. If there is a visual problem in one or both eyes that remain undetected, that area in the brain fails to develop. If detected and corrected early, visual recovery is faster and the potential to achieve perfect vision is possible. But if detected late, the brain’s potential to recover vision is limited. Hence, timing in the detection and treatment is critical.
Treatment is based on determining the cause of amblyopia. One of the more common causes is the presence of an error of refraction that is not the same in both eyes. The patient would then just depend on the eye that sees better. Another cause is strabismus wherein the patient tends to favor one eye and the eye that is misdirected becomes neglected. Other less common cause would be the presence of an eye abnormality that blocks vision such as cataracts or bleeding inside the eye. Treatment and surgery should be done immediately especially if the abnormality is present during the first 3 months of life.
The main objective in treating patients with amblyopia is to restore the vision of the poor eye to the same level as the good eye. For refractive causes, glasses is given as first line in the treatment. Patching is another form of treatment wherein the good eye is patched for several hours a day depending on the level of amblyopia. This is to force the patient to use the eye with the poor vision.

Sometimes, it may be necessary to perform surgery first prior to glasses and patching, such as in the case of cataracts, bleeding inside the eye, and strabismus. Also, amblyopia has also been observed to recur, hence, regular follow ups is advised.
                             EYE PATCHING
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