Optical Coherence Tomography III :
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?
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.


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?
This is a common eye disease affecting nearly 5-10% of children. In this disease a child cannot see well from one or both eyes due to uncorrected refractive error or squint. Unfortunately, Lazy Eye Disease goes undetected as, children do not complain and parents do not realize it. Appropriate treatment at the correct time can restore good 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 for children wh?
Wearing spectacles (glasses) is the most effective and safest treatment option in children. Contact Lenses can be prescribed in children after the age of 12-13 years when they can handle them well and laser correction (LASIK) can be done after the age of 18 years once the power in the eyes become constant. Special glasses and medicines like Pirenzipine are found to be effective in retarding the progression of myopia (near sightedness). There are also methods to reduce hypermetropia (far sightedness) by supporting the process called emmetropization.


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.


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. Please feel free to ask any other queries or clarifications with our squint specialist.