Strabismus (Crossed Eyes)
Strabismus is a condition that can occur in both children and adults, where one or both eyes do not align properly. The eyes do not look in the same direction due to a coordination problem in the eye muscles, leading to misalignment.
Types of Strabismus
Strabismus can be classified in the following ways:
Based on the ability to use both eyes simultaneously:
- Latent (Hidden) Strabismus: The crossed eye is not noticeable when both eyes are used together.
- Intermittent Strabismus: The eye drifts when looking at distant objects but remains straight when focusing on something close or when not paying attention.
- Constant Strabismus: The eye is consistently misaligned.
Based on the age of onset:
- Congenital: Present from birth to 6 months of age.
- Acquired: Occurs after 6 months of age.
Based on the direction of the misalignment:
- Esotropia (inward turning) or Exotropia (outward turning).
- Vertical strabismus: One eye turns up or down.
- Cyclotropia: One eye rotates inward or outward.
Causes of Strabismus
- Eye muscle abnormalities: For example, the eye muscles may have abnormal tissue from birth, often inherited in an autosomal dominant pattern.
- Focusing problems: In hyperopia (farsightedness), the eyes may strain to focus, leading to crossed eyes. Corrective lenses can help align the eyes.
- Nerve issues: Abnormalities in the third, fourth, or sixth cranial nerves that control eye movement.
- Neurological developmental problems: Slower development can lead to problems in coordinating eye movements. Strabismus is more common in these children than in the general population.
- Other conditions: Such as muscular dystrophy, thyroid disorders, etc.
- Idiopathic: When no clear cause is identified, but it may be hereditary.
Symptoms of Strabismus
- Misalignment of the eyes.
- Double vision (seeing one image as two).
- Tilting the head or turning the face to reduce double vision.
- Difficulty with depth perception.
Diagnosis
Strabismus should be diagnosed by an ophthalmologist. The process involves taking a thorough history and performing a physical exam. Vision and eye movement will be assessed, and the angle of misalignment will be measured using a prism to determine the extent of the condition.
Treatment
Treatment depends on the cause of strabismus:
- Correcting refractive errors: For conditions like hyperopia, glasses can help align the eyes.
- Patching: Used to treat lazy eye (amblyopia) caused by strabismus or to reduce intermittent exotropia (outward turning).
- Medication: If strabismus is caused by an underlying condition such as thyroid disease or myasthenia gravis, treatment for those conditions is necessary.
Surgery
- Indications for surgery: Surgery is recommended for congenital strabismus, such as esotropia, before the age of 2 for better chances of binocular vision. For intermittent exotropia after 6 months, surgery can help restore three-dimensional vision.
- Recession: Weakening the eye muscle by moving its attachment point back.
- Resection: Removing part of the eye muscle and reattaching it to make the muscle stronger. Recession is more commonly performed than resection, as it is easier and does not involve removing part of the muscle.
Surgical treatment for cosmetic reasons does not improve vision or restore binocular vision but can help correct the appearance of misalignment. After surgery, the patient may still rely on one eye or alternate eyes for vision.
