Introduction
Strabismus surgery is a common and generally safe procedure performed to realign misaligned eyes and improve vision. Strabismus, sometimes referred to as crossed eyes, occurs when the eyes do not properly coordinate with each other and point in different directions. This results in disruption of binocular vision, depth perception, and other visual abnormalities. In many cases, strabismus requires surgical intervention to realign the eyes and restore function.
The goal of strabismus surgery is to enhance eye alignment and binocular vision by adjusting the position and tension of the extraocular muscles. The eye muscles controlling movement are detached from the sclera, repositioned, and reattached in order to allow the eyes to work together synergistically. This improves cosmetic appearance and can alleviate symptoms such as double vision. With careful pre-operative evaluation and planning, strabismus surgery can produce good outcomes in realigning the eyes.
During strabismus surgery, an incision is made in the conjunctiva and Tenon’s capsule to access the eye muscles. Depending on the direction of misalignment, different techniques are used to tighten or loosen select muscles. The two main approaches are recession, moving the insertion point backward, and resection, removing a portion of the muscle. The ultimate goal is to achieve post-operative orthotropia, the correct positioning of both eyes.
Strabismus surgery dates back over 100 years and techniques continue to advance. When performed by an experienced ophthalmic surgeon, strabismus surgery can restore proper ocular alignment in up to 80% of patients. This article will provide an in-depth overview of strabismus surgery, including diagnostic evaluation, surgical techniques, recovery process, risks, and expected outcomes.
Types of Strabismus and Indications for Surgery
There are several types of strabismus that may require realignment through surgery. The direction of the misalignment determines how it is categorized. Common forms of strabismus amenable to surgery include:
Esotropia – This is an inward turning of one or both eyes, also called crossed eyes. It is the most common form of strabismus. Esotropia causes the eyes to cross and turn inward toward the nose. This usually develops in early childhood. Surgery is aimed at weakening the medial rectus muscle to reduce inward pulling.
Exotropia – In this condition, one or both eyes drift outward. It is also referred to as wall-eyed. Exotropia can cause functional and cosmetic issues. During surgery, the lateral rectus muscle is recessed or repositioned to prevent outward drifting.
Hypertropia – This condition involves vertical misalignment, in which one eye deviates upward. Surgery may transpose the inferior rectus muscle to lower the elevated eye.
Hypotropia – The opposite of hypertropia, this is when one eye turns downward. The superior rectus is adjusted to lift the lowered eye into proper position.
In determining the need for strabismus surgery, the degree of binocular misalignment will be quantified. Symptoms like double vision and loss of depth perception may also indicate surgical correction is warranted. The goal is to restore muscle balance and coordinated eye movements.
Pre-Operative Evaluation and Planning
Careful pre-operative assessment is crucial in strabismus surgery to determine the appropriate surgical plan. The main components of the pre-op workup include:
Comprehensive Eye Exam – This evaluates visual acuity, refractive error, eye health, and full orthoptic status. Eye positioning and movement are observed, along with optic nerve function.
Measuring Misalignment – The deviating angle of the misaligned eye is quantified using prism testing or Hirschberg corneal light reflex evaluation. This identifies the exact degree of strabismic deviation.
Assessing Binocular Vision – Sensory testing evaluates how well the eyes work together for depth perception and fusion. This includes stereoacuity and Worth 4-dot testing.
Determining Impact – The patient’s symptoms from strabismus are noted, including double vision, headaches, eyestrain, and loss of vision. The cosmetic impact is also considered.
Identifying Affected Muscles – Based on the type and angle of deviation, the extraocular muscles requiring intervention are identified. This dictates the surgical plan.
Imaging – Scans like MRI may sometimes be warranted to visualize orbital anatomy and look for underlying issues.
Once complete, the pre-operative workup provides critical details for surgical planning, such as which muscles to operate on, the amount of recession or resection required, use of posterior fixation sutures, and more. This data allows the surgery to be customized for optimal outcomes.
Surgical Techniques and Procedures
The primary goal of strabismus surgery is to reposition the extraocular muscles in order to allow the eyes to realign and work synergistically together. There are several techniques surgeons may employ to achieve this:
Loosening the Muscle – The first step is to access the misaligned muscle(s). An incision is made in the conjunctiva and Tenon’s capsule to expose the sclera. The muscle is then detached from its original insertion point.
Recession – This moves the muscle’s insertion point backward on the globe. It weakens the muscle’s puling action to realign the deviated eye. The amount of recession depends on the severity of deviation.
Resection – A section of the muscle is removed to shorten it and increase its pulling force. This strengthens action in the intended direction.
Transposition – The muscle is detached and reinserted at a new location to alter its vector of pull. This is often used for vertical deviations.
Posterior Fixation Suture – A non-absorbable suture is used to anchor the muscle behind the equator of the eye. This limits overcorrection.
During the procedure, care is taken to avoid damage to surrounding structures like optic nerves and blood vessels. Precise measurements determine how much muscle manipulation is required. The goal is to achieve post-op orthotropia and fusion.
Post-Operative Recovery and Care
The recovery process following strabismus surgery focuses on allowing the eyes to heal while protecting them from irritation and infection. Typical post-operative care involves:
Eye Patches – Alternating patches are worn to minimize eye movement during initial healing, often for several weeks. This prevents the operated muscles from being disturbed.
Eye Drops – Antibiotic drops prevent infection while steroid drops control inflammation. Lubricating drops keep the eyes comfortable.
Ointment – An ophthalmic ointment is sometimes applied along the incision to prevent irritation from eyelid rubbing.
Activity Restriction – Strenuous activity should be avoided during the early recovery period to rest the eyes. Reading, screens, and driving may also be limited.
Follow-Up Exams – Frequent post-op visits assess healing and results. The ophthalmologist evaluates alignment, muscle function, and vision.
The first 1-2 months focus on recovery. While vision may be blurry at first, this generally improves as swelling dissipates and the eyes stabilize. Full healing can take 6 months or longer. Close follow-up care ensures the best outcome.
Risks and Complications
While generally safe, strabismus surgery does carry some risks and potential complications, including:
Infection – Unclean incisions can lead to bacterial infection. This may require antibiotic treatment. Proper sterile technique minimizes this risk.
Bleeding – Hemorrhaging can occur during muscle detachment. Applying pressure and cauterization are used to control bleeding.
Loss of Vision – Damage to the optic nerve or retina is rare but can result in partial or complete vision loss.
Over/Under-correction – Inaccurate surgical dosing leads to persistent misalignment requiring additional surgery.
Double Vision – Some patients experience worsening diplopia if fusion is not achieved post-op. Prisms or therapy may be needed.
Asymmetry – Adjusting only one eye can result in asymmetry. Both eyes may need intervention to balance alignment.
Anesthesia Issues – As with any surgery, risks like breathing issues or drug reactions are possible.
The most common risks like over/under-correction often resolve with a second surgery. Serious complications are infrequent in the hands of an experienced surgeon. Thorough informed consent prepares patients for potential issues.
Long-Term Outcomes and Success Rates
When performed correctly, strabismus surgery can yield very favorable long-term outcomes in realigning the eyes. Some key statistics on the procedure’s effectiveness include:
• Successful alignment is achieved after one surgery in approximately 80% of appropriately selected patients.
• Younger patients tend to have higher success rates than adults. The plasticity of younger brains to integrate the change may play a role.
• Patients with an intermittent deviation have better outcomes than those with constant strabismus.
• Fusion and stereopsis are restored in about 50% of surgeries, greatly improving depth perception.
• The reoccurrence rate of misalignment is estimated to be 5-10% over time. Additional surgery can correct this.
• In cases of residual strabismus, prism lenses often help improve alignment. Vision therapy may also be beneficial.
• Overall, strabismus surgery significantly improves ocular alignment, eye coordination, and appearance when done properly. Complete restoration of visual function is not guaranteed.
• Multiple surgeries are often required over a patient’s lifetime to maintain optimal results. Lifelong follow-up is recommended.
Conclusion
Strabismus surgery is a proven and effective treatment for realigning crossed or misaligned eyes. When the extraocular muscles are unable to keep the eyes straight, surgical adjustment of the muscle insertion points can restore proper alignment and coordination between the eyes.
Careful pre-operative evaluation is necessary to determine the correct surgical approach based on the specific strabismus type and degree of deviation. Recession, resection, transposition and posterior fixation sutures are common techniques to reposition the muscles. While risks like infection and vision loss are possible, they remain relatively low in experienced hands.
Overall, strabismus surgery can successfully realign the eyes in 80% or more of appropriately chosen cases. This improves appearance, depth perception, and symptoms like double vision that disrupt visual function. Though multiple surgeries over a lifetime may be required to maintain results, the procedure is an effective remedy for misaligned eyes when conservative options fail. With advances in surgical techniques, outcomes continue to improve.
بدون دیدگاه