Strabismus Treatment Without Surgery

Overview:

What is a strabismus?

Strabismus or squint is a condition in which the eyes are not aligned properly to focus a fine image on the retina. The eye or both eyes can be deviated upwards, downwards, or sideways. It is due to improper coordination between the extraocular muscles of the eye. Some muscles or one muscle can be fibrosed or tight while others might be looser. If the strabismus occurs during an early age, it can lead to reduced depth perception called stereopsis.

Strabismus is not only cosmetically a disfiguring disease but also associated with reduced vision. Timely recognition of strabismus and early strabismus treatment can lead to a better visual outcome.

Early strabismus treatment strategies include strabismus treatment without surgery such as correction of refractive error, patching, and prescribing prisms. While the surgical procedure includes loosening and tightening of the involved muscles called recession and resection respectively. The following points should be kept in mind for strabismus treatment without surgery and with surgery.

1. Age of the patient at the onset of strabismus
2. Current age
3. Overall health status
4. Patient’s developmental level
5. Concerns of the patient and/or parents
6. Symptoms and signs of visual discomfort
7. Visual demands of the patient
8. Size and frequency of the strabismus
9. Presence or absence of amblyopia

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Types Of Strabismus:

Strabismus is broadly divided into esotropia and exotropia.

Esotropia: In esotropia, there is the inward deviation of one or both eyes.

Exotropia: In exotropia, there is the outward deviation of one or both eyes.

Both the condition can occur in the near and far distance as well as in any other direction of gaze. Besides these two types, strabismus can have an accommodative element, in which the accommodation supplied by the ciliary muscles is less as compared to the convergence power needed.

In another case, esotropia may result due to a high level of hypermetropia labeled as fully accommodative esotropia. One other type is intermittent exotropia, in which the eye is in an outward direction during visual inattention.

What causes squint/ strabismus?

Strabismus can be caused due to sensory or motor discoordination. In some cases, there is opacity in the cornea or lens which leads to strabismus. There can be muscular disintegration problems, as happens in Duane syndrome and others. Strabismus can also occur as a result of surgery for strabismus, in that case, there will be over or under correction.

Differences in refractive error between the two eyes may result in depression of one eye and resulting in strabismus. It is called stimulus deprivation amblyopia.

Complications Of Squint/ Strabismus:

Problems that can occur if squint is not treated?

Various types of problems may arise due to strabismus. These are

Not an eye muscle problem

Strabismus can not be directly related to a muscle problem. In fact, there is a problem in coordination between the eye and brain. There are few cases in which there can be a direct muscular problem e.g., Duane syndrome and Mobius syndrome.

The cosmetic problems

It is the major concern when strabismus is detected in the initial stages. It can lead to various psychosocial problems as well, especially when a child with strabismus has to face other children in school and other places. The disfiguring appearance will lead to low self-esteem.

The seeing problem

The human eye is normally trained to perceive images from both eyes, combine and make up one fine image. Any condition affecting the normal pathway from eye to brain will lead to suppression of that particular eye leading to strabismus.

Diagnosis Of Strabismus:

The initial presentation of strabismus is as followed

• Headache
• Vision problem
• Manifest squint
• Loss of depth perception

To diagnose strabismus, the health care provider will perform the following examinations to reach the final diagnosis

• Visual equity in adults, and retinoscopy in children
• Corneal light reflex test
• Cover/ uncover test
• Complete ophthalmic examination under slit lamp.

Treatment Of Strabismus:

Strabismus Treatment Without Surgery:

1. Optical correction:

The treatment of strabismus starts with optical correction regardless of the cause of strabismus so that binocularity can develop. Full optical correction should be prescribed to patients with hyperopia, anisometropia and astigmatism. Those patients who find it difficult to adopt to full correction, under correction may be prescribed.
The patients should be evaluated time to time to make changes in lens prescription as needed.

Bifocals are advised to patients having fusion potential or if full correction at distance can’t be tolerated. Bifocals are often prescribed to patients with esotropia with high AC/A ratio to reduce strabismus at near. Convex lenses are also advised to those with more strabismus in near as compared to far distance.

Added minus lens power can be temporarily prescribedin young children for intermittent exotropia that measures the same for distance and near or is larger for distance. According to research 70 % patients with intermittent exotropia were managed with concave lens power. Added minus lens power is contraindicated in patients whose exotropia is associated with accommodative insufficiency or who are presbyopic.

If the exotropia remains unchanged with minus lens power the treatment should be stopped. In such cases, multifocal lenses should be used. The patient compliance should be made sure for the better management.

2. Prisms:

Prisms move the image close to the fovea so that sensory fusion can be maintained. Patients who have fusion and strabismus of less than 20 PD are prescribed prisms. Amblyopia, suppression, or ARC are the contraindications for the use of a prism. In spectacles, maximum power of 10–12 PD can be incorporated. Prisms can also help to reduce the compensatory head posture in strabismus. The patients who are treated with prisms, need to be followed periodically.

3. Optometric Vision therapy:

It is an active procedure in which the patient is trained to improve motor and sensory fusion of the patient in order to avoid amblyopia and improve the range of accommodation. The therapy can be used in association with added lens power, prism, or surgery. Patients with longstanding strabismus can be treated successfully. The time duration is 20–60 minutes per day.

4. Pharmacological therapy:

In past, pharmacological therapy was used to treat strabismus patients with miotics like echothiophate iodide as an alternative to glasses. The drugs reduce accommodation and decrease accommodation convergence effort. The starting dose is usually 0.125% phospholine Iodide (1 drop q.d.), tapered to the desired result.

Eight weeks is the total trial period to check its efficacy The pharmacological agent treatment is less effective than glasses and bifocal lenses, because of local and systemic adverse effects.

The treatment should be reserved for patients with facial deformities or with low compliance or children who frequently break their spectacles. Another drug used is atropine 1 % which dilates the pupil in the non-amblyopic eye. The patient wears spectacles with atropine in the non-amblyopic eye. This therapy forces the patient to forcefully accommodate the amblyopic eye. This therapy is more effective for children with moderate amblyopia.

5. Chemo denervation:

The injection of botulinum toxin type A can be used as an alternative or an adjunct to conventional incisional surgery in selected strabismic patients. In this therapy temporary paralysis of the extraocular muscles leads to a change in eye position This change has been reported to result in long-lasting and permanent alteration in ocular alignment. Usually, one injection is sufficient to produce the desired results.

The side effects of the therapy include ptosis and vertical strabismus Although one injection is often sufficient to produce positive results, one-third to one-half of patients may require additional injections. This technique has been most successfully used in patients who have acute abducens nerve palsy and in adults with small-angle deviations.

Treatment and Surgery for a Squint:

Eye- muscle surgery

The non-surgical treatment should be considered before recommending surgery. The surgery should be performed on patients with cosmetic problems, intellectual and psychological problems. Patients with esotropia of more then 15 PD in primary position for near and distance with full refractive correction should be considered for surgery. In exotropia, deviations of more then 20 PD in primary position should be operated.

The patients with accommodative esotropia should not be operated because of developing exotropia post operatively.

Strabismus surgery can restore the ocularalignment to normal, or, at least, closer to normal. Binocular field of vision is expanded in esotropia while reduction of the binocular field occurs for exotropia post operatively. The timing and urgency for surgical referral depend upon the type of strabismus and the age of the patient.

Children with infantile strabismus should be operated prior to 2 years of age. Studies have shown that surgery performed at early age has better outcome of stereopsis and binocular single vision. Binocular vision is achieved when the postsurgical alignment is within 10 PD of orthotropia, whereas a residual deviation of 4 PD or less is usually required to achieve stereopsis.

In some patients multiple surgeries may be needed to obtain orthophoria. Surgery is rarely performed at early age for other childhood strabismic deviations (e.g., intermittent exotropia). The overall success rate for surgical therapy for horizontal strabismus is approximately 60percent, when success is defined as an ocular deviation 10 PD or less at 6 weeks post-surgery.

Surgical procedure:

What happens during squint surgery?

The surgical procedure consists of monocular recession and resection of horizontal recti muscles of the non-fixing eye. The muscle is exposed by a limbal conjunctival incision with two radial relieving incisions. The muscle is then separated from its attachments by round-edge curved conjunctival scissors and destabilized by a muscle hook.

Two 6/0 poly galectin absorbable sutures are used for two whip stitches; one at the upper border and the other at the lower boundary of muscle in close proximity to its insertion point during the recession, and far from the insertion point in the muscle cone during muscle resection. At the time of recession, the muscle is incised in close proximity to its insertion point, and during muscle resection, then it is incised far from its insertion point, finally, the muscle is allowed to retract and drawback.

Sutures are carried out of the conjunctival incision and left unfastened with one edge at the 12 o’clock position with the other in the opposite position. Recession is measured with a caliper from posteriorly at the beginning of the muscle insertion point and afterward, the muscle is sutured directly on the sclera by piercing the sclera with both the upper and lower suture needles opposite each other.

Both needles are passed gently up to half the width of the sclera under resistance without penetrating deeply into uveal tissue. The uveal penetration is confirmed when the needle passed very easily through the sclera without resistance. As the sutures are tied, the retracted muscle is lifted and brought forward to be fastened to the attachment site, and it is sutured at its normal anatomical insertion point in case of resection.

Absorbable sutures are used to close the conjunctiva. An antibiotic/steroid eye ointment (neomycin with betamethasone) is applied and the eye is bandaged for 24 hours.

On every postoperative outpatient follow-up visit, a complete orthoptic assessment is performed, including visual acuity and a photograph of the patient to measure the angle of deviation. The final best-corrected visual acuity and angle of deviation are documented on a sixth-month post-treatment follow-up.

Post Operative Complications:

Risks of squint surgery

These includes

• Diplopia
• Dellen
• Chemosis
• Pyogenic granuloma
• Anterior segment ischemia
• Scleral perforation
• Endophthalmitis
• Subconjunctival abscess
• Slipped muscle/ lost muscle

Squint Eye Treatment at Home:

The treatment of strabismus mainly depends on the type of squint you are facing. There are a few steps that can be followed at home. These includes

• In refractive type of strabismus (fully accommodative esotropia), the child should be encouraged to put on the refractive glasses all the time at home. The regular usage of glasses will help in reducing the angle of deviation.
• Patching should be performed regularly. The better eye is covered with a patch for at least 50 to 60 minutes per day for the time duration of the age in weeks. Regular patching will force the lazy or amblyopic eye to work more efficiently and hence improvement in squint and vision is made.
• In convergence insufficiency, orthoptic exercises(pencil push-ups) are performed at home. A target or pencil is held at an arm length, the patient is asked to focus the pencil and gradually bring the pencil towards the nose until blurring of vision is noticed. The exercise is performed several times a day.

Conclusion:

The treatment of the strabismus mostly depends on the age of the patient and the angle of deviation at the time of presentation. Early detection and early treatment may result in a better outcome. Besides this, compliance of the patient is crucial for maintaining the treatment for example in children, a good visual outcome can be achieved with proper and timely patching of the eyes and putting on refractive glasses.

When to get medical advice?

You should get immediate medical help if you notice any squinting in your child’s eye, or if there is a problem in recognizing a person at a distance and not able to play games at a near distance, as well as any complaints of headache should arise a concern about ophthalmic examination.

Will a squint affect my child’s vision?

If not recognized and treated on time, yes it can affect vision. However, there are some types of strabismus such as alternating esotropia, in which vision is preserved and the only problem is the squinting behavior of the eyes.

Will a squint make my child unhappy?

Squint has an impact on the psychosocial behavior of children. When it comes to social interaction, yes squint will make your child unhappy. People asking questions and laughing over the squinted eyes is a major concern for many parents.

Can a squint be corrected?

Yes, squint can be corrected surgically and non-surgically. In the initial stages (age below 8 years) non-surgical therapies and glasses are advised to achieve maximum stabilization of the squint, later on, the remaining squint can be corrected with surgery.

Strabismus vs amblyopia? are they the same condition or medical diagnosis?

Amblyopia is the visual deprivation of one or both eyes, mainly occurring during the age of 8 years and below. The main causes for amblyopia are strabismus, refractive error, any opacity in the media, and astigmatism. While strabismus is the inward or outward deviation of the eyeball. The cause of strabismus includes motor and sensory problems.