Medication is used for strabismus in certain circumstances. In 1989, the US FDA approved Botulinum toxin therapy for strabismus in patients over 12 years old. Most commonly used in adults, the technique is also used for treating children, in particular children affected by infantile esotropia. The toxin is injected in the stronger muscle, causing temporary and partial paralysis. The treatment may need to be repeated three to four months later once the paralysis wears off. Common side effects are double vision, droopy eyelid, overcorrection, and no effect. The side effects typically resolve also within three to four months. Botulinum toxin therapy has been reported to be similarly successful as strabismus surgery for people with binocular vision and less successful than surgery for those who have no binocular vision.

When strabismus is congenital or develops in infancy, it can cause amblyopia, in which the brain ignores input from the deviated eye. Even with therapy for amblyopia, stereoblindness may occur. The appearance of strabismus may also be a cosmetic problem. One study reported 85% of adult strabismus patients "reported that they had problems with work, school, and sports because of their strabismus." The same study also reported 70% said strabismus "had a negative effect on their self-image." A second operation is sometimes required to straighten the eyes.

The prognosis for each patient with esotropia will depend upon the origin and classification of their condition. However, in general, management will take the following course:

1. Identify and treat any underlying systemic condition.

2. Prescribe any glasses required and allow the patient time to 'settle into' them.

3. Use occlusion to treat any amblyopia present and encourage alternation.

4. Where appropriate, orthoptic exercises can be used to attempt to restore binocularity.

5. Where appropriate, prismatic correction can be used, either temporarily or permanently, to relieve symptoms of double vision.

6. In specific cases, and primarily in adult patients, botulinum toxin can be used either as a permanent therapeutic approach, or as a temporary measure to prevent contracture of muscles prior to surgery

7. Where necessary, extra-ocular muscle surgery can be undertaken to improve cosmesis and, on occasion, restore binocularity.

Suppression may treated with vision therapy, though there is a wide range of opinions on long-term effectiveness between eye care professionals, with little scientific evidence of long-term improvement of suppression, if the underlying cause is not addressed (strabismus, amblyopia, etc.).

A determination of the prevalence of anisometropia has several difficulties. First of all, the measurement of refractive error may vary from one measurement to the next. Secondly, different criteria have been employed to define anisometropia, and the boundary between anisometropia and isometropia depend on their definition.

Several studies have found that anisometropia occurs more frequently and tends to be more severe for persons with high ametropia, and that this is particularly true for myopes. Anisometropia follows a U-shape distribution according to age: it is frequent in infants aged only a few weeks, is more rare in young children, comparatively more frequent in teenagers and young adults, and more prevalent after presbyopia sets in, progressively increasing into old age.

One study estimated that 6% of those between the ages of 6 and 18 have anisometropia.

Notwithstanding research performed on the biomechanical, structural and optical characteristics of anisometropic eyes, the underlying reasons for anisometropia are still poorly understood.

Anisometropic persons who have strabismus are mostly far-sighted, and almost all of these have (or have had) esotropia. However, there are indications that anisometropia influences the long-term outcome of a surgical correction of an inward squint, and vice versa. More specifically, for patients with esotropia who undergo strabismus surgery, anisometropia may be one of the risk factors for developing consecutive exotropia and poor binocular function may be a risk factor for anisometropia to develop or increase.

Refractive surgery causes only minimal size differences, similar to contact lenses. In a study performed on 53 children who had amblyopia due to anisometropia, surgical correction of the anisometropia followed by strabismus surgery if required led to improved visual acuity and even to stereopsis in many of the children ("see:" Refractive surgery#Children).

Young children with strabismus normally suppress the visual field of one eye (or part of it), whereas adults who develop strabismus normally do not suppress and therefore suffer from double vision (diplopia). This also means that adults (and older children) have a higher risk of post-operative diplopia after undergoing strabismus surgery than young children. Patients who have undergone strabismus surgery at a young age often have monofixation syndrome (with peripheral binocular fusion and a central suppression scotoma).

A comprehensive eye examination including an ocular motility (i.e., eye movement) evaluation and an evaluation of the internal ocular structures will allow an eye doctor to accurately diagnose the exotropia. Although glasses and/or patching therapy, exercises, or prisms may reduce or help control the outward-turning eye in some children, surgery is often required.

There is a common form of exotropia known as "convergence insufficiency" that responds well to orthoptic vision therapy including exercises. This disorder is characterized by an inability of the eyes to work together when used for near viewing, such as reading. Instead of the eyes focusing together on the near object, one deviates outward.

"Consecutive exotropia" is an exotropia that arises after an initial esotropia. Most often it results from surgical overcorrection of the initial esotropia. It can be addressed with further surgery or with vision therapy; vision therapy has shown promising results if the consecutive exotropia is intermittent, alternating and of small magnitude. (Consecutive exotropia may however also spontaneously develop from esotropia, without surgery or botulinum toxin treatment.)

Because of the risks of surgery, and because about 35% of people require at least one more surgery, many people try vision therapy first. This consists of visual exercises. Although vision therapy is generally not covered by American health insurance companies, many large insurers such as Aetna have recently begun offering full or partial coverage in response to recent studies.

Strabismus surgery is sometimes recommended if the exotropia is present for more than half of each day or if the frequency is increasing over time. It is also indicated if a child has significant exotropia when reading or viewing near objects or if there is evidence that the eyes are losing their ability to work as a single unit (binocular vision). If none of these criteria are met, surgery may be postponed pending simple observation with or without some form of eyeglass and/or patching therapy. In very mild cases, there is a chance that the exotropia will diminish with time. The long-term success of surgical treatment for conditions such as intermittent exotropia is not well proven, and surgery can often result in a worsening of symptoms due to overcorrection. Evidence from the available literature suggests that unilateral surgery was more effective than bilateral surgery for individuals affected with intermittent exotropia.

The surgical procedure for the correction of exotropia involves making a small incision in the tissue covering the eye in order to reach the eye muscles. The appropriate muscles are then repositioned in order to allow the eye to move properly. The procedure is usually done under general anesthesia. Recovery time is rapid, and most people are able to resume normal activities within a few days. Following surgery, corrective eyeglasses may be needed and, in many cases, further surgery is required later to keep the eyes straight.

When a child requires surgery, the procedure is usually performed before the child attains school age. This is easier for the child and gives the eyes a better chance to work together. As with all surgery, there are some risks. However, strabismus surgery is usually a safe and effective treatment.

The appropriate treatment for binocular diplopia will depend upon the cause of the condition producing the symptoms. Efforts must first be made to identify and treat the underlying cause of the problem. Treatment options include eye exercises, wearing an eye patch on alternative eyes, prism correction, and in more extreme situations, surgery or botulinum toxin.

If diplopia turns out to be intractable, it can be managed as last resort by obscuring part of the patient's field of view. This approach is outlined in the article on diplopia occurring in association with a condition called "horror fusionis".

According to a Cochrane review of 2012, controversies remain regarding type of surgery, non-surgical intervention and age of intervention.

The aims of treatment are as follows:

The elimination of any amblyopia

A cosmetically acceptable ocular alignment

long term stability of eye position

binocular cooperation.

Controversy has arisen regarding the selection and planning of surgical procedures, the timing of surgery and about what constitutes a favourable outcome.

1. Selection and planning

Some ophthalmologists, notably Ing and Helveston, favour a prescribed approach often involving multiple surgical episodes whereas others prefer to aim for full alignment of the eyes in one procedure and let the number of muscles operated upon during this procedure be determined by the size of the squint.

2. Timing and outcome

This debate relates to the technical anatomical difficulties of operating on the very young versus the possibility of an increased potential for binocularity associated with early surgery. Infants are often operated upon at the age of six to nine months of age and in some cases even earlier at three or four months of age. Some emphasize the importance of intervening early such as to keep the duration of the patient's abnormal visual experience to a minimum. Advocates of early surgery believe that those who have their surgery before the age of one are more likely to be able to use both eyes together post-operatively.

A Dutch study (ELISSS) compared early with late surgery in a prospective, controlled, non-randomized, multicenter trial and reported that:

"Children operated early had better gross stereopsis at age six as compared to children operated late. They had been operated more frequently, however, and a substantial number of children in both [originally-recruited] groups had not been operated at all."

Other studies also report better results with early surgery, notably Birch and Stager and Murray et al. but do not comment on the number of operations undertaken. A recent study on 38 children concluded that surgery for infantile esotropia is most likely to result in measureable stereopsis if patient age at alignment is not more than 16 months.

Another study found that for children with infantile esotropia early surgery decreases the risk of dissociated vertical deviation developing after surgery.

Aside the strabismus itself, there are other aspects or conditions that appear to improve after surgery or botulinum toxin eye alignment. Study outcomes have indicated that after surgery the child catches up in development of fine-motor skills (such as grasping a toy and handling a bottle) and of large-muscle skills (such as sitting, standing, and walking) in case a developmental delay was present before. Evidence also indicates that as of the age of six, strabismic children become less accepted by their peers, leaving them potentially exposed to social exclusion starting at this age unless their eye positioning is corrected by this time ("see also:" Psychosocial effects of strabismus).

Esotropia is a form of strabismus in which one or both eyes turns inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance. It is the opposite of exotropia and usually involves more severe axis deviation than esophoria. Esotropia is sometimes erroneously called "lazy eye", which describes the condition of amblyopia—a reduction in vision of one or both eyes that is not the result of any pathology of the eye and cannot be resolved by the use of corrective lenses. Amblyopia can, however, arise as a result of esotropia occurring in childhood: In order to relieve symptoms of diplopia or double vision, the child's brain will ignore or "suppress" the image from the esotropic eye, which when allowed to continue untreated will lead to the development of amblyopia. Treatment options for esotropia include glasses to correct refractive errors (see accommodative esotropia below), the use of prisms and/or orthoptic exercises and/or eye muscle surgery. The term is from Greek "eso" meaning "inward" and "trope" meaning "a turning".

Management of this condition is surgical and typically involves reducing the strength of the superior rectus muscle or anterior transposition of the inferior oblique muscle of the affected eyes.

Several different surgical procedures exist for the correction of DVD including: inferior oblique anteriorization, inferior oblique anteriorization plus resection, superior rectus recession, superior rectus recession plus posterior fixation suture, and inferior oblique myectomy, though there is insufficient evidence to determine which procedure results in the best outcomes for patients.

Exotropia is a form of strabismus where the eyes are deviated outward. It is the opposite of esotropia and usually involves more severe axis deviation than exophoria. People with exotropia often experience crossed diplopia. Intermittent exotropia is a fairly common condition. "Sensory exotropia" occurs in the presence of poor vision. Infantile exotropia (sometimes called "congenital exotropia") is seen during the first year of life, and is less common than "essential exotropia" which usually becomes apparent several years later.

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. There have also been some reports of people that can "control" their afflicted eye. The term is from Greek "exo" meaning "outward" and "trope" meaning "a turning".

Temporary binocular diplopia can be caused by alcohol intoxication or head injuries, such as concussion (if temporary double vision does not resolve quickly, one should see an optometrist or ophthalmologist immediately). It can also be a side effect of benzodiazepines or opioids, particularly if used in larger doses for recreation, the anti-epileptic drugs Phenytoin and Zonisamide, and the anti-convulsant drug Lamotrigine, as well as the hypnotic drug Zolpidem and the dissociative drugs Ketamine and Dextromethorphan. Temporary diplopia can also be caused by tired and/or strained eye muscles or voluntarily. If diplopia appears with other symptoms such as fatigue and acute or chronic pain, the patient should see an ophthalmologist immediately.

Dissociated vertical deviation (DVD) is an eye condition which occurs in association with a squint, typically infantile esotropia. The exact cause is unknown, although it is logical to assume it is from faulty innervation of eye muscles.

Esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. It is a type of heterophoria.

Causes include:

- Refractive errors

- Divergence insufficiency

- Convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies.

Unlike esotropia, fusion is possible and therefore diplopia is uncommon.

Monofixation syndrome (MFS) (also: microtropia or microstrabismus) is an eye condition defined by less-than-perfect binocular vision. It is defined by a small angle deviation with suppression of the deviated eye and the presence of binocular peripheral fusion. That is, MFS implies peripheral fusion without central fusion.

Aside the manifest small-angle deviation ("tropia"), subjects with MFS often also have a large-angle latent deviation ("phoria"). Their stereoacuity is often in the range of 3000 to 70 arcsecond, and a small central suppression scotoma of 2 to 5 deg.

A rare condition, MFS is estimated to affect only 1% of the general population. There are three distinguishable forms of this condition: primary constant, primary decompensating, and consecutive MFS. It is believed that primary MFS is a result of a primary sensorial defect, predisposing to anomalous retinal correspondence.

Secondary MFS is a frequent outcome of surgical treatment of congenital esotropia. A study of 1981 showed MFS to result in the vast majority of cases if surgical alignment is reached before the age of 24 months and only in a minority of cases if it is reached later.

MFS was first described by Marshall Parks.

The first aims of management should be to identify and treat the cause of the condition, where this is possible, and to relieve the patient's symptoms, where present. In children, who rarely appreciate diplopia, the aim will be to maintain binocular vision and, thus, promote proper visual development.

Thereafter, a period of observation of around 9 to 12 months is appropriate before any further intervention, as some palsies will recover without the need for surgery.

The majority of patients remain symptom free and able to maintain binocularity with only a slight face turn. Amblyopia is uncommon and, where present, rarely dense. This can be treated with occlusion, and any refractive error can also be corrected.

Duane syndrome cannot be cured, as the "missing" cranial nerve cannot be replaced, and traditionally there has been no expectation that surgery will result in any increase in the range of eye movement. Surgical intervention, therefore, has only been recommended where the patient is unable to maintain binocularity, where they are experiencing symptoms, or where they are forced to adopt a cosmetically unsightly or uncomfortable head posture in order to maintain binocularity. The aims of surgery are to place the eye in a more central position and, thus, place the field of binocularity more centrally also, and to overcome or reduce the need for the adoption of an abnormal head posture. Occasionally, surgery is not needed during childhood, but becomes appropriate later in life, as head position changes (presumably due to progressive muscle contracture).

Surgical approaches include:

- Medial rectus recession in the involved eye or both eyes. By weakening the medial rectus muscles this procedure improves the crossed-eye appearance but does not improve outward eye movements (abductions).

- Morad et al. showed improved abduction after modest unilateral medial rectus recession and lateral rectus resection in a subgroup of patients with mild eye retraction and good adduction before surgery.

- Lateral transposition of the vertical muscles described by Rosenbaum has been shown to improve range of movement of the eye. The surgical procedure produces 40-65 degrees of binocular field. Orbital wall fixation of the lateral rectus muscle (muscle is disinserted and reattached to lateral orbital wall) is recommended an effective method to inactivate a lateral rectus muscle in cases of marked anomalous innervation and severe cocontraction.

This is most commonly achieved through the use of fresnel prisms. These slim flexible plastic prisms can be attached to the patient's glasses, or to plano glasses if the patient has no refractive error, and serve to compensate for the inward misalignment of the affected eye. Unfortunately, the prism only correct for a fixed degree of misalignment and, because the affected individual's degree of misalignment will vary depending upon their direction of gaze, they may still experience diplopia when looking to the affected side. The prisms are available in different strengths and the most appropriate one can be selected for each patient. However, in patients with large deviations, the thickness of the prism required may reduce vision so much that binocularity is not achievable. In such cases it may be more appropriate simply to occlude one eye temporarily. Occlusion would never be used in infants though both because of the risk of inducing stimulus deprivation amblyopia and because they do not experience diplopia.

Other management options at this initial stage include the use of botulinum toxin, which is injected into the ipsilateral medial rectus (botulinum toxin therapy of strabismus). The use of BT serves a number of purposes. Firstly, it helps to prevent the contracture of the medial rectus which might result from its acting unopposed for a long period. Secondly, by reducing the size of the deviation temporarily it might allow prismatic correction to be used where this was not previously possible, and, thirdly, by removing the pull of the medial rectus it may serve to reveal whether the palsy is partial or complete by allowing any residual movement capability of the lateral rectus to operate. Thus, the toxin works both therapeutically, by helping to reduce symptoms and enhancing the prospects for fuller ocular movements post-operatively, and diagnostically, by helping to determine the type of operation most appropriate for each patient.

Most patients are diagnosed by the age of 10 years and Duane's is more common in girls (60 percent of the cases) than boys (40 percent of the cases). A French study reports that this syndrome accounts for 1.9% of the population of strabismic patients, 53.5% of patients are female, is unilateral in 78% of cases, and the left eye (71.9%) is affected more frequently than the right. Around 10–20% of cases are familial; these are more likely to be bilateral than non-familial Duane syndrome. Duane syndrome has no particular race predilection.

The eye findings of Parinaud's Syndrome generally improve slowly over months, especially with resolution of the causative factor; continued resolution after the first 3–6 months of onset is uncommon. However, rapid resolution after normalization of intracranial pressure following placement of a ventriculoperitoneal shunt has been reported.

Treatment is primarily directed towards etiology of the dorsal midbrain syndrome. A thorough workup, including neuroimaging is essential to rule out anatomic lesions or other causes of this syndrome. Visually significant upgaze palsy can be relieved with bilateral inferior rectus recessions. Retraction nystagmus and convergence movement are usually improved with this procedure as well.

Optic papillitis is a specific type of optic neuritis. Inflammation of the optic nerve head is called "papillitis" or "intraocular optic neuritis"; inflammation of the orbital portion of the nerve is called "retrobulbar optic neuritis" or "orbital optic neuritis". It is often associated with substantial losses in visual fields, pain on moving the globe, and sensitivity to light pressure on the globe. It is often an early sign of multiple sclerosis.

Papillitis may have the same appearance as papilledema. However, papillitis may be unilateral, whereas papilledema is almost always bilateral. Papillitis can be differentiated from papilledema by an afferent pupillary defect (Marcus Gunn pupil), by its greater effect in decreasing visual acuity and color vision, and by the presence of a central scotoma. Papilledema that is not yet chronic will not have as dramatic an effect on vision. Because increased intracranial pressure can cause both papilledema and a sixth (abducens) nerve palsy, papilledema can be differentiated from papillitis if esotropia and loss of abduction are also present. However, esotropia may also develop secondarily in an eye that has lost vision from papillitis. Retrobulbar neuritis, an inflamed optic nerve, but with a normal-appearing nerve head, is associated with pain and the other findings of papillitis. Pseudopapilledema is a normal variant of the optic disk, in which the disk appears elevated, with indistinct margins and a normal vascular pattern. Pseudopapilledema sometimes occurs in hyperopic individuals.

Workup of the patient with papillitis includes lumbar puncture and cerebrospinal fluid analysis. B henselae infection can be detected by serology. MRI is the preferred imaging study. An abnormal MRI is associated with a worse visual outcome.

Parinaud's syndrome, also known as dorsal midbrain syndrome, vertical gaze palsy, and Sunset Sign, is an inability to move the eyes up and down. It is caused by compression of the vertical gaze center at the rostral interstitial nucleus of medial longitudinal fasciculus (riMLF). The eyes lose the ability to move upward and down .

It is a group of abnormalities of eye movement and pupil dysfunction. It is caused by lesions of the upper brain stem and is named for Henri Parinaud (1844–1905), considered to be the father of French ophthalmology.