Dr Ben Wild
Overview |
Eye movements are controlled by 6 extra-ocular muscles. The superior rectus pulls the eye upwards, the inferior rectus pulls the eye downwards, the lateral rectus pulls the eye outwards and the medial rectus pulls the eye inwards. The superior oblique muscle connects to the eye after passing through a pulley called the trochlea and is mainly responsible for rotating the eye inwards and pushing the eye downwards. The inferior oblique follows a similar path as the superior oblique, except underneath the eye and does not travel through a pulley system.
A frontal image of a right eye with the extra-ocular muscles. If any of these muscles are too tight, too loose, too strong or too weak, there is the potential for an eye turn (strabismus).
Esotropia is a type of strabismus (eye turn) where one eye is seen crossing inwards compared to the other but all of the eye muscles still have full range of motion. There are many different causes of esotropia and each has a different treatment and prognosis.
Infantile esotropia is made apparent within the first 6 months after birth in an otherwise healthy child. Accommodative esotropia usually presents around 3-4 years old and is due to either uncorrected farsightedness or the accommodative system working too hard to see up close. Consecutive esotropia may occur after a surgery to correct the eye turn. Other types include basic esotropia that can develop at any age, convergence excess esotropia where the eye turn is only noticed when looking at something close, and divergent insufficiency esotropia where the eye turn is only noticed when looking far away.
A normal pair of eyes looking off into the distance.
An image showing the right eye is turned inwards. This is an esotropia style of strabismus.
Signs and Symptoms |
Signs
One eye is turned inwards compared to the other. It may be constant or intermittent (comes and goes), it may be dependent on where the patient is looking, it may just be one eye or it may alternate eyes.
Symptoms
Possible double vision, lack of depth perception.
Causes and Risk Factors |
Causes
Birth anomalies, uncorrected farsightedness, developmental delays.
Risk Factors
Family history of strabismus.
Prevention and Treatment |
Prevention
1st eye exam around 1 year old followed by another at 3-4 years old to ensure proper development of the eyes and eye muscles.
Treatments
· Glasses or contacts after a cycloplegic refraction (prescription done after dilating drops).
· Treat any amblyopia (lazy eye) by patching the good eye 2hrs/day to full time.
· Vision therapy (eye exercises to regain proper eye muscle control).
· Surgery by age of 1 or 2 if born with strabismus or upon 1st discovering a strabismus is constant (doesn’t come and go).
Prognosis |
If born with strabismus, surgery can align the eyes but the patient may need several re-alignment surgeries in their lifetime. There is also only a slim chance of gaining depth perception. If the strabismus develops after the age of 3-4, full glasses prescription and vision therapy can often correct the alignment issue, and if not, surgery can re-align the eyes. Regaining depth perception in this case is likely but not promised.