The most extensive epidemiological survey on this congenital malformation has been carried out by Dharmasena et al and using English National Hospital Episode Statistics, they calculated the annual incidence of anophthalmia, microphthalmia and congenital malformations of orbit/lacrimal apparatus from 1999 to 2011. According to this study the annual incidence of congenital microphthalmia in the United Kingdom was 10.8 (8.2 to 13.5) in 1999 and 10.0 (7.6 to 12.4) in 2011.

The abnormalities common to cat eye syndrome were first cataloged in 1899. It was described in association with a small marker chromosome in 1965. Early reports of cat eye syndrome discuss the possibility of chromosome 13 involvement. Now, CES is considered to be present with the chromosome 22 trisomy findings.

Cat eye syndrome (CES), or Schmid–Fraccaro syndrome, is a rare condition caused by the short arm (p) and a small section of the long arm (q) of human chromosome 22 being present three (trisomic) or four times (tetrasomic) instead of the usual two times. There is no significant reduction in life expectancy in patients who are not afflicted with one of CES' life-threatening abnormalities.

If binocular vision is present and head position is correct, treatment is not obligatory.

Treatment is required for: visual symptoms, strabismus, or incorrect head position.

Acquired cases that have active inflammation of the superior oblique tendon may benefit from local corticosteroid injections in the region of the trochlea.

The goal of surgery is to restore free ocular rotations. Various surgical techniques have been used:

- Harold Brown advocated that the superior oblique tendon be stripped. A procedure named sheathotomy. The results of such a procedure are frequently unsatisfactory because of reformation of scar tissue.

- Tenotomy of the superior oblique tendon (with or with out a tendon spacer) has also been advocated. This has the disadvantage that it frequently produces a superior oblique paresis.

- Weakening of the inferior oblique muscle of the affected eye may be needed to compensate for iatrogenic fourth nerve palsy.

During surgery, a traction test is repeated until the eye rotations are free and the eye is anchored in an elevated adducted position for about two weeks after the surgery. This maneuver is intended to prevent the reformation of scar tissue in the same places. Normalization of head position may occur but restoration of full motility is seldom achieved. A second procedure may be required.

In itself, NSML is not a life-threatening diagnosis, most people diagnosed with the condition live normal lives. Obstructive cardiomyopathy and other pathologic findings involving the cardiovascular system may be a cause of death in those whose cardiac deformities are profound.

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.

The treatment, and therefore prognosis, varies depending upon the underlying tumour.

Colobomas of the iris may be treated in a number of ways. A simple cosmetic solution is a specialized cosmetic contact lens with an artificial pupil aperture. Surgical repair of the iris defect is also possible. Surgeons can close the defect by stitching in some cases. More recently artificial iris prosthetic devices such as the Human Optics artificial iris have been used successfully by specialist surgeons. This device cannot be used if the natural lens is in place and is not suitable for children. Suture repair is a better option where the lens is still present.

Vision can be improved with glasses, contact lenses or even laser eye surgery but may be limited if the retina is affected or there is amblyopia.

Microphthalmia (Greek: μικρός "micros" = small; ὀφθαλμός "ophthalmos" = eye), also referred as microphthalmos, is a developmental disorder of the eye in which one (unilateral microphthalmia) or both (bilateral microphthalmia) eyes are abnormally small and have anatomic malformations. It is different from nanophthalmos in which the eye is small in size but has no anatomical alterations.

Knobloch syndrome is a rare genetic disorder presenting severe eyesight problems and often a defect in the skull. It was named after W.H. Knobloch, who first described the syndrome in 1971. A usual occurrence is a degeneration of the vitreous humour and the retina, two components of the eye. This breakdown often results in the separation of the retina (the light-sensitive tissue at the back of the eye) from the eye, called retinal detachment, which can be recurrent. Extreme myopia (near-sightedness) is a common feature. The limited evidence available from electroretinography suggests a cone-rod pattern of dysfunction is also a feature.

Knobloch syndrome is caused by mutations in an autosomal recessive inherited gene. These mutations have been found in the COL18A1 gene that instructs for the formation of a protein that builds collagen XVIII. This type of collagen is found in the basement membranes of various body tissues. Its deficiency in the eye is thought to be responsible for affecting normal eye development. There are two types of Knobloch syndrome and the case has been made for a third.

When caused by mutations in the COL18A1 gene it is called Knobloch syndrome type 1. The genes causing types II and III have yet to be identified.

Knobloch syndrome is also characterised by cataracts, dislocated lens with skull defects such as occipital encephalocele and occipital aplasia. Encephalocele is a neural tube defect where the skull has not completely closed and sac-like protrusions of the brain can push through the skull; (it can also result from other causes).

In Knobloch’s syndrome this is usually seen in the occipital region, and aplasia is the underdevelopment of tissue again in this reference in the occipital area.

It is suggested that, once diagnosed, individuals be routinely followed by a cardiologist, endocrinologist, dermatologist, and other appropriate specialties as symptoms present.

It is recommended that those with the syndrome who are capable of having children seek genetic counseling before deciding to have children. As the syndrome presents frequently as a "forme fruste" (incomplete, or unusual form) variant, an examination of all family members must be undertaken. As an autosomal dominant trait there is a fifty percent chance with each child that they will also be born with the syndrome. Although fully penetrant, since the syndrome has variable expressivity, one generation may have a mild expression of the syndrome, while the next may be profoundly affected.

Once a decision to have children is made, and the couple conceives, the fetus is monitored during the pregnancy for cardiac evaluation. If a gross cardiac malformation is found, parents receive counseling on continuing with the pregnancy.

Other management is routine care as symptoms present:

1. For those with endocrine issues (low levels of thyrotopin [a pituitary hormone responsible for regulating thyroid hormones], follicle stimulating hormone) drug therapy is recommended.

2. For those who are disturbed by the appearance of lentigines, cryosurgery may be beneficial. Due to the large number of lentigines this may prove time consuming. An alternative treatment with tretinoin or hydroquinone creams may help.

3. Drug therapies for those with cardiac abnormalities, as those abnormalities become severe enough to warrant the use of these therapies. ECG's are mandatory prior to any surgical interventions, due to possible arrythmia.

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 number of cases is around 0.5 to 0.7 per 10,000 births, making it a relatively rare condition.

In Brown's original series there was a 3:2 predominance of women to men and nearly twice as many cases involved the right eye as the left. 10% of cases showed bilaterality. Familial occurrence of Brown's syndrome has been reported.

There have been cases of improvement in extra-ocular movement with botulinum toxin injection.

Telecanthus is often associated with many congenital disorders. Congenital disorders such as Down syndrome, fetal alcohol syndrome, Cri du Chat syndrome, Klinefelter syndrome, Turner syndrome, Ehlers-Danlos syndrome, Waardenburg syndrome often present with prominent epicanthal fold and if these folds are nasal (most commonly are) they will cause telecanthus.

Fig of the used terms

Foster–Kennedy syndrome (also known as Gowers–Paton–Kennedy syndrome, Kennedy's phenomenon or Kennedy's syndrome) refers to a constellation of findings associated with tumors of the frontal lobe.

Although "Foster–Kennedy syndrome" is equated with "Kennedy syndrome", it should not be confused with Kennedy disease, which is named for William R. Kennedy.

"Pseudo-Foster–Kennedy syndrome" is defined as one-sided optic atrophy with papilledema in the other eye but with the absence of a mass.

Cri du chat syndrome, also known as chromosome 5p deletion syndrome, 5p− syndrome (pronounced "Five P Minus") or Lejeune’s syndrome, is a rare genetic disorder due to chromosome deletion on chromosome 5. Its name is a French term ("cat-cry" or "call of the cat") referring to the characteristic cat-like cry of affected children. It was first described by Jérôme Lejeune in 1963. The condition affects an estimated 1 in 50,000 live births across all ethnicities and is more common in females by a 4:3 ratio.

Causes of the one and a half syndrome include pontine hemorrhage, ischemia, tumors, infective mass lesions such as tuberculomas, and demyelinating conditions like multiple sclerosis.

Telecanthus (from the Greek word "tele" (τῆλε) meaning far, and the Latin word canthus, meaning either corner of the eye, where the eyelids meet) refers to increased distance between the medial canthi of the eyes, while the inter-pupillary distance is normal. This is in contrast to hypertelorism, where the inter-pupillary distance is increased.

The distance between the inner corner of the left eye and the inner corner of the right eye, is called intercanthal distance. In most people, the intercanthal distance is equal to the distance between the inner corner and the outer corner of each eye, that is, the width of the eye. The average interpupillary distance is 60–62 millimeters (mm), which corresponds to an intercanthal distance of approximately 30–31 mm. The situation, where intercanthal distance is intensely bigger than the width of the eye, is called telecanthus (tele= Greek τηλε = far, and Greek ακανθα = thorn). This can be an ethnic index or an indication for hypertelorism or hypotelorism, if it is combined with abnormal relation to the interpupillary distance (A D STEAS).

"Traumatic Telecanthus" refers to telcanthus resulting from traumatic injury to the nasal-orbital-ethmoid (NOE) complex. The diagnosis of traumatic telecanthus requires a measurement in excess of those normative values. The pathology can be either unilateral or bilateral, with the former more difficult to measure.

Several other corneal ectatic disorders also cause thinning of the cornea:

- Keratoglobus is a very rare condition that causes corneal thinning primarily at the margins, resulting in a spherical, slightly enlarged eye. It may be genetically related to keratoconus.

- Pellucid marginal degeneration causes thinning of a narrow (1–2 mm) band of the cornea, usually along the inferior corneal margin. It causes irregular astigmatism that, in the early stages of the disease can be corrected by spectacles. Differential diagnosis may be made by slit-lamp examination.

- Posterior keratoconus, a distinct disorder despite its similar name, is a rare abnormality, usually congenital, which causes a nonprogressive thinning of the inner surface of the cornea, while the curvature of the anterior surface remains normal. Usually only a single eye is affected.

- Post-LASIK ectasia is a complication of LASIK eye surgery.

Diagnosis is based on the distinctive cry and accompanying physical problems. These common symptoms are quite easily observed in infants. Affected children are typically diagnosed by a doctor or nurse at birth. Genetic counseling and genetic testing may be offered to families with individuals who have cri du chat syndrome. Prenatally the deletion of the cri du chat related region in the p arm of chromosome 5 can be detected from amniotic fluid or chorionic villi samples with BACs-on-Beads technology. G-banded karyotype of a carrier is also useful. Children may be treated by speech, physical and occupational therapists. Heart abnormalities often require surgical correction.

In early stages of keratoconus, glasses or soft contact lenses can suffice to correct for the mild astigmatism. As the condition progresses, these may no longer provide the person with a satisfactory degree of visual acuity, and most practitioners will move to manage the condition with rigid contact lenses, known as rigid, gas-permeable, (RGP) lenses. RGP lenses provide a good level of visual correction, but do not arrest progression of the condition.

In people with keratoconus, rigid contact lenses improve vision by means of tear fluid filling the gap between the irregular corneal surface and the smooth regular inner surface of the lens, thereby creating the effect of a smoother cornea. Many specialized types of contact lenses have been developed for keratoconus, and affected people may seek out both doctors specialized in conditions of the cornea, and contact lens fitters who have experience managing people with keratoconus. The irregular cone presents a challenge and the fitter will endeavor to produce a lens with the optimal contact, stability and steepness. Some trial-and-error fitting may prove necessary.

Heterochromia has also been observed in those with Duane syndrome.

Treatment is a relatively simple surgery in which excess skin of the outer lids is removed or tendons and muscles are shortened with one or two stitches. General anesthesia is sometimes used before local anesthetics are injected into the muscles around the eye. Prognosis is excellent if surgery is performed before the cornea is damaged.

@Congenital entropion:: may resolve with time ,or Hotz procedure

@Cicatricial entropion::

1 Anterior lamellar resection

2 Tarsal wedge resection

3 Transposition of tarso conjunctival wedge

4 Posterior lamellar graft

@Senile entropion::

1 Wies operation

2 Transverse everting suture

3 Quicker procedure