Exotropia is one of the most common forms of strabismus, a condition that refers to any misalignment of the eyes in which one eye deviates outward (away from the nose) while the other fixates normally. Where as Esotropia is the condition where one eye deviates inward (toward the nose).Hence Exotropia and Esotropia are both forms of strabismus but opposite of each other.

Esotropia is the most common type of strabismus in infants, while exotropia often begins between the ages of 2 and 4. About 4 percent of all children in the United States have some form of strabismus. It occurs equally in males and females and is sometimes hereditary. The condition can also develop later in life.

The brain's ability to see three-dimensional objects depends on proper alignment of the eyes. When both eyes are properly aligned and aimed at the same target, the visual portion of the brain fuses the forms into a single image. When one eye turns inward, outward, upward, or downward, two different pictures are sent to the brain. This causes loss of depth perception and binocular vision.

Treatment for intermittent exotropia does not have to occur immediately. As a matter of fact, early surgery has the potential of disturbing the ability of the brain for fusion in the future and can cause a permanent reduction in vision (amblyopia).

Treatment consists of vision therapy, patching, glasses and/or surgery. The most successful form of treatment is vision therapy. In a comparative study using both Optometric and Ophthalmological journals, vision therapy had an overall success rate of 78% as compared to surgery of 48%. Thus, surgery should be reserved only for the large angle intermittent exotropes or when vision therapy is not as successful as expected.

The causes of exotropia are not fully understood. There are six muscles that control eye movement, four that move it up and down and two that move it side to side. All these muscles must be coordinated and working properly in order for the brain to see a single image. When one or more of these muscles doesn't work properly, some form of strabismus may occur. Strabismus is more common in children with disorders that affect the brain such as cerebral palsy, Down syndrome, hydrocephalus, and brain tumors.

The best treatment for convergence insufficiency with or without strabismus is vision therapy which re-establishes the reflexes of convergence. Treatment usually consists of both in office and home exercises. Recent home computerized therapy programs have become effective in eliminating the symptoms associated with convergence insufficiency. This mode of treatment is very successful.

Esotropia is a form of eye misalignment where one eye looks ahead and the other turns just before the nose. It is an ordinary state in newborns as less than one quarter of babies are born with both eyes facing straight ahead. The eyes usually come into the proper position over the next three months as the two eyes begin to work together.

Esotropia is a form of strabismus, or "squint", in which one or both eyes turns inward. The state can be always present, or take place occasionally, and can give the affected individual a "cross-eyed" appearance. Esotropia is at times incorrectly called "lazy eye", which describes the situation of amblyopia - a decline in vision of one or both eyes which is not the result of any pathological injury of the visual pathway and which cannot be determined by the use of corrective lenses. Amblyopia , though, happen as a result of esotropia happening in childhood: In order to reduce symptoms of diplopia or double vision, the child's brain will pay no attention to or "suppress" the image from the esotropic eye, which when allowed continuing untreated will lead to the development of amblyopia.
Treatment options for esotropia include glasses to correct refractive errors, the use of prisms and/or orthoptic exercises and/or eye muscle surgery.

How to detect Esotropia?
In some cases, esotropia is not self-correcting but in fact becomes inferior. Childhood esotropia usually develops over the first six months and affects about 1 percent of full-term newborns. It might happen during transient episodes, causing a delay in the diagnosis.

Determine the alternate prism test to measure the angle of difference in the eyes. An angle of deviation greater than 20 prism diopters is considered to be infantile esotropia. Patients that have a deviation between 20 and 40 have a little chance of resolving the esotropia, but a deviation of greater than 40 prism diopters will not often resolve itself.

Check for amblyopia, which should be powerfully suspected in cases of infantile esotropia, particularly in the crossed eye.

Verify for extra ocular motor signs such as impaired binocularity, incomitance and scotomas. Patients that achieve an almost usual alignment within the first two years almost certainly have regular sensory and motor functions.

Look for additional underlying causes of infantile esotropia. It has been associated with a greater likelihood of craniofacial, neurologic and ocular abnormalities. A host of other problems also can cause esotropia.

Treatment for Esotropia -

1. Identify and treat any primary systemic situation.

2. Recommend any glasses necessary and allow the patient time to 'settle into' them.

3. Use occlusion to cure any amblyopia there and give confidence alternation.

4. Where appropriate, orthoptic workout can be used to try to re-establish binocularity.

5. Where appropriate, prismatic correction can be used, either for the short term or everlastingly, to relieve symptoms of double vision.

6. In specific cases, and primarily in adult patients, Botulinum Toxin can be used either as a permanent beneficial approach, or as a temporary measure to prevent contracture of muscles earlier to surgery

7. Where essential, extra-ocular muscle surgery can be undertaken to recover cosmesis and, on occurrence, re-establish binocularity.

Photorefractive keratectomy (PRK) is a laser eye surgery procedure that is carried out with the key intent to correct a patient’s vision. PRK permanently changes the shape of the frontal corneal tissue using an excimer laser, which is a high-precision ultraviolet chemical laser. The outer layer of the cornea (epithelium) is removed, and then a small amount of the corneal tissue is burnt off using the laser. Such an ablation renders the desired shape to the cornea and allows for optimal refraction. PRK is a technologically advanced surgical procedure.

 For instance, a computer system tracks the eye position around 4,000 times per second, redirecting laser pulses for precise ablation. As mentioned above, the epithelium is removed prior to ablation. This does not hamper the patient’s vision, since the epithelium is a soft and regenerating layer, which is capable of completely replacing itself within a matter of days. However, the deeper layers, once burnt off, will remain that way because they possess limited regenerative capability. This theory is the cornerstone of the Photorefractive keratectomy surgical procedure. PRK differs from LASIK in a way that the epithelium is removed in PRK and allowed to regenerate.

On the other hand, LASIK does not involve epithelium removal. Instead it consists of cutting a flap in the cornea in order to make the desired incisions. Compared to LASIK, a patient who has undergone PRK experiences more pain and recovery is slow. However, both procedures are similar in the respect that they make use of a laser. Photorefractive keratectomy is a viable procedure, but it does have possible complications. Apart from slow recovery and pain, the patient may experience glares and halos. As in any refractive surgery, there is a possibility of over- or under-correction. Eye surgeons typically perform PRK on one eye at a time, in order to gauge the results of the procedure and ensure its efficacy. In a majority of cases, PRK has proven to be a safe and efficacious procedure to correct myopia. However, since the procedure is irreversible, it is recommended that the patient consults an eye doctor instead of jumping on a conclusion.

PRK may be performed on one eye at a time to assess the results of the procedure and ensure adequate vision during the healing process. Activities requiring good binocular vision may have to be suspended between surgeries and during the sometimes extended healing periods.

Astigmatism is a vision disorder that occurs when the cornea of the eye is uneven in shape. More rarely, it can result from the way in which the eye's natural crystalline lens refracts light. Either condition causes a distorted image to fall on the retina.

The human eye works much like a camera with two lenses -- the cornea, which is a clear membrane that covers the front of the eye, and the natural crystalline lens, which is located behind the pupil. These two lenses work together to focus light on the retina, which is the membrane that covers the back two-thirds of the eye and works like the film in a camera. A normal cornea should be curved equally in all directions, allowing light to focus exactly on the surface of the retina. Most vision problems result from an irregularity in the curvature of the cornea or in the shape of the eye.

Astigmatism is very common and new eye care products have been popping up in the marketplace to help people with the condition. No one really knows what causes astigmatism. Some are born with it, while others develop it later in life. It can be hereditary. Sometimes people develop the condition after cataract or cornea surgery. Since there isn't a known cause for astigmatism, there isn't a way to prevent it.

Visit the eye doctor regularly. A routine eye exam can determine if you have astigmatism. Special instruments may be used to determine eye diseases. Some symptoms that are associated with astigmatism are nearsightedness, farsightedness, blurry and uneven vision.

Astigmatism can be treated surgically or nonsurgically. Prescription eyeglasses and contact lenses or laser vision correction surgery correct most cases of astigmatism. The most prevalent nonsurgical correction is a prescription for rigid gas permeable (RGP) contact lenses. Because it is rigid, an RGP lens will fill in the irregular areas of the cornea with tears, creating a smooth spherical surface and correcting astigmatism. Special soft contact lenses called torics also compensate for the astigmatic shape of the corneas. In those cases where the astigmatism arises from the eye's natural crystalline lens rather than the cornea, a special bitoric contact lens may be prescribed. It offers refracting surfaces on the front and back to correct the problem in much the same way that eyeglasses do.

If you cannot tolerant contact lenses, not comfortable wearing them, just want to be free from glasses or contacts, you may opt to have some form of vision correction procedure performed by a qualified eye surgeon. LASIK, the most popular form of laser vision correction, can provide correction for relatively high degrees of nearsightedness and astigmatism as well as some cases of farsightedness and astigmatism.