Strabismus Surgery

What is Strabismus?

Strabismus is the common term for misaligned eyes. Some people also use terms like tropia or more informal terms such as cross-eyed or wall-eyed. Essentially, strabismus is a condition in which both eyes are not properly, simultaneously aligned. One or both of the eyes may turn out (exotropia), in (esotropia), down (hypotropia) or up (hypertropia). An eye turn may be constant or intermittent. Whether in adults or children, Strabismus often does not go away on its own; however, strabismus of all types is treatable. Strabismus is relatively common and may be present in up to 5% of the population. Strabismus surgery is often considered when more conservative methods such as glasses, patching, prism lenses, and vision therapy do not improve a patient's eye alignment.

A Brief Review of the Extraocular Muscles

Each eye has six (6) extraocular muscles that are controlled by three (3) cranial nerves (oculomotor nerve [CN III], trochlear nerve [CN IV], and abducens nerve [CN VI]). These muscles move the eye in all positions - up, down, in, out, rotate in, rotate out, etc.

Eye Muscles

What is Strabismus Surgery?

Treatment for strabismus is two-fold: straighten the eye(s) and improve binocular vision. Not all cases of strabismus require surgery; however, severe or persistent strabismus may require surgical intervention. Contrary to what some may think, the eye itself is not removed from its normal location in the orbit. An ophthalmologist (sometimes referred to as strabismologist) makes an incision and performs microsurgery to reposition one or more muscles on the eyeball itself.

Surgery often involves one of two procedures: recession or resection. A recession involves removing a muscle from the eye and reattaching it to the eye at a different location. The end result is a relative weakening of the muscle's primary action. A resection involves removing a segment of a muscle and reattaching the shortened muscle at the original position. The end result is a relative strengthening of the muscle's primary action.

Many strabismic surgeons use an adjustable suture technique during the operation. This allows the surgeon to fine-tune the positioning of the operated eye after surgery without needed to perform another operation. Adjustable sutures may even be adjusted only a few hours after surgery as the patient recovers.

Who is Eligible for Strabismus Surgery?

Children under one year old up to elderly adults may be candidates for strabismus surgery. The best recommendation is to discuss your case and your concerns with an eye care provider. The critical item to keep in mind is the twofold goal of strabismus surgery: align the eye(s) and improve binocular vision. In young children, the visual system is still developing. Aligning the eyes and simultaneously working to improve amblyopia ([lazy eye] if present) may help the child's visual system recover and develop normally. In adults, the visual system may have developed adaptive mechanisms to compensate for the eye deviation. An adult visual system may have already learned to suppress vision in the deviated eye to eliminate double vision (diplopia). These patients may require a greater therapeutic approach to restore binocular vision.

What Should I Expect with Strabismus Surgery?

Strabismus surgery is usually done under general anesthesia (though some patients may be awake if needed). A series of pre-operation appointments will likely occur. During these appointments, your eye doctor will evaluate the health of your eyes, evaluate your vision (visual acuity, depth perception), evaluate the amount the eye turn, and take a thorough history regarding your eye condition. Expect to undergo a few visits before the actual surgery, as some insurances may require certain conditions or treatments to be tried or met prior to issuing approval for surgery. This may include a general health examination with your primary care provider or a subspecialist if you have a specific health condition.

Some medications that impact blood clotting ability may be modified or discontinued to prevent abnormal bleeding during the surgery itself. Your eye doctor will review what medications are safe for use around the time of surgery.

In the vast majority of cases, strabismus surgery is done in an outpatient setting. This means that the patient is discharged to their home after the procedure and following discharge authorization from the surgeon. Expect a series of follow-up examinations following surgery; these follow-up exams do somewhat depend on the patient and condition, and often a series of follow-ups are performed in the days and weeks following surgery.   It is not uncommon to have mild pain and swelling immediately following surgery. The eye may become red, and blood may gather around the white of the eye (termed a subconjunctival hemorrhage). There may also be some bruising around the skin and soft tissue of the eyelids. Patients are often reminded to limit strenuous activity for 1-2 weeks following surgery and to avoid activities like swimming and hot tubs for a short period of time while the eye(s) heals.

What are the Benefits to Strabismus Treatment?

Besides straightening the eyes, restoration of normal binocular vision has a number of benefits. This may include: improved visual acuity (clarity of vision), improved depth perception, improved visual field (peripheral vision), reduction or elimination of double vision, and even improved personal wellbeing.

It is essential to discuss the goals and expectations of strabismus treatment with your eye care provider.

How will I know if I need Strabismus Surgery?

Essentially, there is no real way to know if you are a candidate for strabismus surgery without consulting your eye care specialist. Prior to surgery, a series of examinations are performed to evaluate the health of the eyes and to determine the alignment of the eyes. This allows the surgeon to evaluate which muscles may be are contributing to strabismus and which muscles may need to be altered to improve eye alignment. Prism lenses are often used to measure the degree of strabismus. In some cases, a patient may be recommended to try glasses, eye patching, or other non-surgical methods of treatment prior to considering strabismus surgery.

What are the Potential Risks of Strabismus Surgery?

As with any surgery, strabismus surgery is not without risks to the patient. The chance of any serious complication from strabismus surgery is often low, but complications can occur that negatively impact the patient's outcome. This include:

  • Poor, unsatisfactory, or residual eye alignment
  • Double vision
  • Infection
  • Abnormal bleeding
  • Abnormal scarring
  • Granuloma formation
  • Slipped or lost muscle during surgery
  • Globe (scleral) perforation
  • Anesthesia-related complications

Strabismus surgery is a standard ophthalmological procedure, and most patients achieve a significant improvement in eye alignment surgery. Some patients may require glasses or other refractive correction, prisms, or re-operation to achieve quality vision. As previously stated, each case is unique and should be discussed with your eye care provider so that you understand the goals, limitations, and expectations of strabismus surgery.  

What are Non-Surgical Strabismus Treatments?

Glasses/Prisms

Glasses and sometimes prism lense may help with eye alignment. It is not uncommon for glasses with or without prismatic corrective lenses to be required prior to considering strabismus surgery. Glasses act to attempt to equalize clarity of vision for each eye. Prism lenses help a patient compensate for a deviated eye, be it up, down, in, or out.

Orthoptics

Orthoptics is often specific to eye muscle and alignment training. The term itself means "straight eyes". Orthoptics is not as common in the US market as some other areas of the world. Orthoptics are often prescribed and monitored by an orthoptist who often works with a strabismus surgeon. The primary goal of orthoptics is to promote eye alignment and improve the range of binocular fusion.

Vision Therapy

Although sometimes confused with orthoptics, vision therapy takes a broader approach to strabismus. Vision therapy (VT) does work eye alignment but also works to optimize the patient's visual system as a whole. This may include oculomotor therapy to promote eye alignment and improve the range of binocular fusion, as well as accommodative therapy, eye-hand coordination, visual-perceptual therapy, and others. Vision therapy is often performed by or under the direction of an optometrist.

Botox Injection

Botulinum toxin (commercially known as the trademarked Botox, Dysport, or Prosign) is often thought of as a cosmetic treatment for aging signs such as for wrinkles, forehead lines, crow's feet, and others. Botulinum toxin has had mixed reviews for use in strabismus. There is a lack of reliable guidelines for the use of and amount of botulinum toxin for strabismus treatment; however, botulinum toxin has been provent to reduce the amount of strabismus by amounts comparable to strabismus surgery.

References

Botulinum toxin for the treatment of strabismus https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6464099/

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