When both the eyes of a person are not in alignment with each other it is known as squint or strabismus.
Nearly 40% patients with squint can be cured by spectacles and/or eye exercises. However, a large majority require an operation. Squint operations are very safe and should be done at the earliest. Generally if the eyes are not aligned for more than 6 months in a child, irreversible damage to the three dimensional vision occurs, which is only partly reversible. Squint surgeries are performed successfully even in 4 month old children.
If surgery is required it should be done in most cases within six months after the squint is noticed to avoid any irreversible damage to three dimensional vision.
What is squint (strabismus)?
Squint is a misalignment of the two eyes where both eyes are not looking in the same direction. This misalignment may be constant or may be present throughout the day or it may appear occasionally and the rest of the time the eyes may be straight; this is called as intermittent squint.
What causes squint?
The exact cause of squint is not known.
Six muscles control the movement of each eye (see picture). Each of these muscles acts along with its counterpart in the other eye to keep both the eyes aligned properly. A loss of coordination between the muscles of the two eyes leads to misalignment.
Sometimes a refractive error like hypermetropia (far sightedness) or an eye muscle paralysis may lead to deviation of the eye.
Poor vision in an eye because of some other eye disease like cataract etc. may also cause the eye to deviate. Therefore it is important in all cases of squint, especially in children, to have a thorough eye checkup to rule out any other cause of loss of vision.
What is 3D vision?
When both the eyes have good vision and are aligned properly, they focus on the same object. Each of the eyes sends a picture of the same object, viewed from a slightly different angle. These two images reach the brain where they are fused to form a single three-dimensional picture with depth perception. This is known as 3D vision. This gets affected in children with squint.
What are the problems faced by a patient with squint?
When the eyes are not aligned properly, each of the eyes is focusing on a different object and sends signal to the brain. These two different images reaching the brain lead to various problems that are different in children and adults.
In children it can cause loss of depth perception (3D vision) and lazy Eye Disease (poor development of vision in the squinting eye).
An adult can't ignore the image from either eye, and therefore they can have double vision. This can be very annoying and may interfere with work. Loss of 3D vision and cosmetic deformity are also causes of concern.
What are the symptoms of squint?
In a child, the parents may notice the deviation of eyes. It is important to remember that the eyes of a newborn are rarely aligned at birth. Most establish alignment at 3-4 weeks of age. Therefore squint in any child who is more than one month old must be taken seriously and should be evaluated by an ophthalmologist.
Adults noticing double vision, or misalignment of the eyes should get themselves checked up too.
How is squint diagnosed?
Squint is diagnosed by an ophthalmologist specializing in that field. The doctor will do a few special tests to confirm the presence of squint and find out the reason behind the squint. In some cases there may be a false appearance of squint due to broad nasal bridge in a child. This is known as pseudo squint.
What is the aim of treating a squint?
The aim of treating a squint in order of importance is:
To preserve or restore vision
Straighten the eyes
Restore 3D vision
When should a squint be treated?
In a child, the treatment of squint and any associated amblyopia should be started as soon as possible. Generally speaking the younger the age at which amblyopia is treated the better the chance of recovery of vision.
Remember that the child would never grow out of squint. A delay in treatment may decrease the chances of getting a good alignment and vision. So earlier the better!
So earlier the better!
What are the treatment options?
Glasses
Patching therapy
Surgery
Are glasses necessary?
If the child has significant refractive error, glasses are a must. In some cases wearing glasses may correct squint. In other cases, wearing glasses help the eyes to see clearly. This clear vision is very important for the treatment of amblyopia, and also for maintaining the alignment of the eyes after they have been corrected by surgery. Remember surgery cannot replace the need for glasses.
What is patching therapy?
In some children, squints cause the affected eye to become 'lazy' and stop working properly. Patching the 'good' eye will make the lazy eye work harder, which in turn will improve vision. Remember patching only improves vision it does not treat the squint, although the un-patched eye will appear to be straight while the patch is worn. Sometimes when the patch is removed the squint may be temporarily more noticeable but later returns to the pre-patching position.
The patch is made from non-irritating material to prevent rashes, and spectacles are worn over the patch.
It is thought that the patching therapy works best for children below 7-8 years of age.
How long should the patch be worn?
This varies according to the child's need and may vary from less than 1 hour a day to all day. It is important that the child is involved in some near vision activity during patching, such as coloring, reading or schoolwork. This will achieve maximum effect and help the child comply with patching because it distracts attention from the patch. Perseverance with patching is vital. The patching needs to be continued at least till the age of 7-8 years.
Squint surgery
Treatment of squint generally requires eye muscle surgery. However, some patients may need glasses, prisms, medication, or even left untreated. The best way to determine whether straightening of the eyes is possible and appropriate is to undergo an examination by a strabismus surgeon who is experienced in treating adults.
Is adult squint surgery only cosmetic?
In the past, most eye doctors thought that adults with misaligned eyes could not be treated successfully, or that treatment was "only cosmetic". Advances in the management of misaligned eyes now provide benefits to most adults as well as children. Treating adults via strabismus can improve depth perception, the way the two eyes work together, and the field of vision. Many patients report improved self-esteem, communication skills, job opportunities, together with enhanced reading and driving skills.
What are the complications of squint surgery?
Like any other surgery, squint surgery is not without complications. Significant complications of strabismus surgery include endophthalmitis (infection of the eye ball) and retinal detachment, both as a result of accidental perforation of the globe during surgery.
These complications are very rare: Perforation of the globe may occur in 0.3% - 2.8% of cases resulting in endophthalmitis in less than 1:3500 cases and retinal detachment in even fewer cases.
What are the success rates of a squint surgery?
Nearly 80-90% patients are successfully corrected in the straight-ahead position with just one surgery. In some patients the surgery may be only partially successful. In some patients the eye alignment will change over time, resulting in the need for additional surgery after a few months or years
How is squint surgery performed?
The squint surgery is done under local or general anesthesia depending on the age of the patient and the complexity of the squint.
The surgical technique used in our hospital is fornix incision and adjustable technique, which is state- of- the- art.
