Median longitudinal ear length greater than two standard deviations above the mean and median ear width greater than two standard deviations above the mean (objective); or, apparent increase in length and width of the pinna (subjective).

Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear.

A degree of language development that is significantly below the norm for a child of a specified age.

A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.

Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.

Distance between nasal base and midline upper lip vermilion border more than 2 SD above the mean. Alternatively, an apparently increased distance between nasal base and midline upper lip vermilion border.

Reduction in the vertical distance between the upper and lower eyelids.

The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective).

A form of strabismus with one or both eyes turned inward ('crossed') to a relatively severe degree, usually defined as 10 diopters or more.

Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).

Microphthalmia is an eye abnormality that arises before birth. In this condition, one or both eyeballs are abnormally small. In some affected individuals, the eyeball may appear to be completely missing; however, even in these cases some remaining eye tissue is generally present. Such severe microphthalmia should be distinguished from another condition called anophthalmia, in which no eyeball forms at all. However, the terms anophthalmia and severe microphthalmia are often used interchangeably. Microphthalmia may or may not result in significant vision loss.\n\nPeople with microphthalmia may also have a condition called coloboma. Colobomas are missing pieces of tissue in structures that form the eye. They may appear as notches or gaps in the colored part of the eye called the iris; the retina, which is the specialized light-sensitive tissue that lines the back of the eye; the blood vessel layer under the retina called the choroid; or in the optic nerves, which carry information from the eyes to the brain. Colobomas may be present in one or both eyes and, depending on their size and location, can affect a person's vision.\n\nPeople with microphthalmia may also have other eye abnormalities, including clouding of the lens of the eye (cataract) and a narrowed opening of the eye (narrowed palpebral fissure). Additionally, affected individuals may have an abnormality called microcornea, in which the clear front covering of the eye (cornea) is small and abnormally curved.\n\nBetween one-third and one-half of affected individuals have microphthalmia as part of a syndrome that affects other organs and tissues in the body. These forms of the condition are described as syndromic. When microphthalmia occurs by itself, it is described as nonsyndromic or isolated.

Primary or spontaneous detachment of the retina occurs due to underlying ocular disease and often involves the vitreous as well as the retina. The precipitating event is formation of a retinal tear or hole, which permits fluid to accumulate under the sensory layers of the retina and creates an intraretinal cleavage that destroys the neurosensory process of visual reception. Vitreoretinal degeneration and tear formation are painless phenomena, and in most cases, significant vitreoretinal pathology is found only after detachment of the retina starts to cause loss of vision or visual field. Without surgical intervention, retinal detachment will almost inevitably lead to total blindness (summary by McNiel and McPherson, 1971).

Diminished clarity of vision.

A coloboma of the iris.

A congenital abnormality of the cornea in which the cornea and the anterior segment of the eye are smaller than normal. The horizontal diameter of the cornea does not reach 10 mm even in adulthood.

Rhythmic, involuntary sinusoidal oscillations of one or both eyes. The waveform of pendular nystagmus may occur in any direction.

A macular coloboma is an area of 2-6 disk diameters in which there is total or considerable chorioretinal maldevelopment, often with extasia of the underlying sclera which produces the white appearance visible ophthalmoscopically (summary by Phillips, 1970).

A congenital anomaly in which a part or the whole of the cornea acquires the characteristics of sclera, resulting in clouding of the cornea.

Anterior segment dysgeneses (ASGD or ASMD) are a heterogeneous group of developmental disorders affecting the anterior segment of the eye, including the cornea, iris, lens, trabecular meshwork, and Schlemm canal. The clinical features of ASGD include iris hypoplasia, an enlarged or reduced corneal diameter, corneal vascularization and opacity, posterior embryotoxon, corectopia, polycoria, an abnormal iridocorneal angle, ectopia lentis, and anterior synechiae between the iris and posterior corneal surface (summary by Cheong et al., 2016). Anterior segment dysgenesis is sometimes divided into subtypes including aniridia (see 106210), Axenfeld and Rieger anomalies, iridogoniodysgenesis, Peters anomaly, and posterior embryotoxon (Gould and John, 2002). Some patients with ASGD1 have been reported with the Peters anomaly subtype. In its simplest form, Peters anomaly involves a central corneal opacity, but it may also involve adherent iris strands. Some patients have keratolenticular content or cataract. The underlying defects in this form of congenital corneal opacity reside in the posterior stroma, Descemet membrane, and corneal endothelium. The disorder results from abnormal migration or function of neural crest cells and may include abnormalities of other anterior segment structures, such as the lens and iris (summary by Withers et al., 1999).

Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.