Causes a ‘white reflex’ in the affected eye (leukocoria), prompting further investigation.

The primary vitreous used in formation of the eye during fetal development remains in the eye upon birth and is hazy and scarred. The symptoms are leukocoria, strabismus, nystagmus and blurred vision, blindness.

Alezzandrini syndrome is a very rare syndrome characterized by a unilateral degenerative retinitis, followed after several months by ipsilateral vitiligo on the face and ipsilateral poliosis. Deafness may also be present.

Although there are no specific symptoms for this condition, common complains include progressively increasing pelvic pain during menstruation and haematocolpos due to the buildup of blood in the body. Other symptoms may include swelling of the abdomen, nausea and vomiting during menstruation, and pelvic pain. Fertility may also be affected.

The condition often leads to an increased need for C-sections due to the smaller uteruses.

Congenital cystic eye (also known as "CCE" or "cystic eyeball") is an extremely rare ocular malformation where the eye fails to develop correctly "in utero" and is replaced by benign, fluid-filled tissue. Its incidence is unknown, due to the very small number of cases reported. An audit by Duke-Elder of the medical literature from 1880 to 1963 discovered only 28 cases. The term was coined in 1937 by the renowned ophthalmologist Ida Mann.

Embryologically, the defect is thought to occur around day 35 of gestation, when the vesicle fails to invaginate. Dysgenesis of the vesicle later in development may result in coloboma, a separate and less severe malformation of the ocular structures.

CCE is almost always unilateral, but at least 2 cases of bilateral involvement have been described. Patients may also present with skin appendages attached to the skin surrounding the eyes. Association with intracranial anomalies has been reported.

Treatment of CCE is usually by enucleation, followed by insertion of an ocular implant and prosthesis.

Trotter's syndrome is a cluster of symptoms associated with certain types of advanced nasopharyngeal carcinoma. The cause of pain is the mandibular nerve of the foramen ovale, through which the tumor enters the calvarium. Symptoms include the following:

1. Unilateral conductive deafness due to middle ear effusion

2. Trigeminal neuralgia due to perineural spread

3. Soft palate immobility

4. Difficulty opening mouth

OHVIRA, or Herlyn-Werner-Wunderlich syndrome, is a rare anomaly of the Müllerian ducts. In most cases, it is presented as a double uterus with unilateral obstructed (or blind) hemivagina and ipsilateral renal agenesis. Although the true incidence is unknown, it has been reported to be between 0.1% and 3.8%.

Hemifacial hypertrophy (also termed facial hemihypertrophy, facial hemihyperplasia, or Friedreich's disease) abbreviated as (HFH) is rare congenital disease characterized by unilateral enlargement of the head and teeth. It is classified as true HFH (THFH) with unilateral enlargement of the viscerocranium, and partial HFH (PHFH) in which not all structures are enlarged. Hemifacial hypertrophy can cause a wide spectrum of defects or may involve only muscle or bone. it is usually treated surgically. It is believed to be a minor form of hemihypertrophy.

It can be unilateral or bilateral.

- Sometimes, a unilateral choanal atresia is not detected until much later in life because the baby manages to get along with only one nostril available for breathing.

- Bilateral choanal atresia is a very serious life-threatening condition because the baby will then be unable to breathe directly after birth as babies are obligate nasal breathers (they mainly use their noses to breathe). In some cases, this may present as cyanosis while the baby is feeding, because the oral air passages are blocked by the tongue, further restricting the airway. The cyanosis may improve when the baby cries, as the oral airway is used at this time. These babies may require airway resuscitation soon after birth.

Encephalocraniocutaneous lipomatosis (ECCL), otherwise known as Haberland syndrome, is a rare condition primarily affecting the brain, eyes, and skin of the head and face. It is characterized by unilateral subcutaneous and intracranial lipomas, alopecia, unilateral porencephalic cysts, epibulbar choristoma and other ophtalmic abnormalities.

It was named after Haberland and Perou who first described it.

There are four grades of microtia:

- Grade I: A less than complete development of the external ear with identifiable structures and a small but present external ear canal

- Grade II: A partially developed ear (usually the top portion is underdeveloped) with a closed [stenotic] external ear canal producing a conductive hearing loss.

- Grade III: Absence of the external ear with a small peanut-like vestige structure and an absence of the external ear canal and ear drum. Grade III microtia is the most common form of microtia.

- Grade IV: Absence of the total ear or anotia.

Sometimes babies born with choanal atresia also have other abnormalities:

- coloboma

- heart defects

- mental retardation

- growth impairment

- others (see also CHARGE syndrome)

Also any condition that causes significant depression of the nasal bridge or midface retraction can be associated with choanal atresia. Examples include the craniosynostosis syndromes such as Crouzon syndrome, Pfeiffer syndrome, Treacher Collins and Antley-Bixler syndrome.

Although large vestibular aqueducts are a congenital condition, hearing loss may not be present from birth. Age of diagnosis ranges from infancy to adulthood, and symptoms include fluctuating and sometimes progressive sensorineural hearing loss and disequilibrium.

Other symptoms of the syndrome include:

- retroorbital pain due to pain in the area supplied by the ophthalmic branch of the trigeminal nerve (fifth cranial nerve),

- abducens nerve palsy (sixth cranial nerve), and

- otitis media.

Other symptoms can include photophobia, excessive lacrimation, fever, and reduced corneal sensitivity.

The syndrome is usually caused by the spread of an infection into the petrous apex of the temporal bone.

Tumors within the nerve canaliculi initially present with unilateral sensorineural hearing loss, unilateral tinnitus, or disequilibrium (vertigo is rare, on account of the slow growth of neuromas). Speech discrimination out of proportion to hearing loss, difficulty talking on the telephone are frequent accompaniments. Tumors extending into the CPA will likely present with disequilibrium or ataxia depending on the amount of extension on the brainstem. With brainstem extension, midfacial and corneal hypesthesia, hydrocephalus, and other cranial neuropathies become more prevalent.

For example, involvement of CN V from a cerebellopontine mass lesion often results in loss of the ipsilateral (same side of the body) corneal reflex (involuntary blink).

Patients with larger tumours can develop Bruns nystagmus ('dancing eyes') due to compression of the flocculi.

The goal of medical intervention is to provide the best form and function to the underdeveloped ear.

Crossed dystopia (syn.unilateral fusion cross fused renal ectopia) is a rare form of renal ectopia where both kidneys are on the same side of the spine. In many cases, the two kidneys are fused together, yet retain their own vessels and ureters. The ureter of the lower kidney crosses the midline to enter the bladder on the contralateral side. Both renal pelvis can lie one above each other medial to the renal parenchyma (unilateral long kidney) or the pelvis of the crossed kidney faces laterally (unilateral "S" shaped kidney). Urogram is diagnostic.

The anomaly can be diagnosed through ultrasound of urography, but surgical intervention is only necessary if there are other complications, such as tumors or pyelonephritis.

Patients present with acute unilateral decreased vision, photopsias and central or paracentral scotoma. An antecedent viral prodrome occurs in approximately one-third of cases. Myopia is commonly seen in patients.

Eye exam during the acute phase of the disease reveals multiple discrete white to orange spots at the level of the RPE or deep retina, typically in a perifoveal location (around the fovea).

The vestibular aqueduct acts as a canal between the inner ear and the cranial cavity. Running through it is a tube called the endolymphatic duct, which normally carries a fluid called endolymph from the inner ear to the endolymphatic sac in the cranial cavity. When the endolymphatic duct and sac are larger than normal, as is the case in large vestibular aqueduct syndrome, endolymph is allowed to travel back from the endolymphatic sac into the inner ear. This often results fluctuations in hearing levels. Enlarged vestibular aqueducts often occur with other inner ear development problems, such as cochlear deformities. Enlarged vestibular aqueducts are part of the classic Mondini deformity. Enlarged vestibular aqueducts with enlarged endolymphatic sacs occur in Pendred syndrome which is caused by a defect on chromosome 7q31.. Enlarged vestibular aqueducts can also occur in Branchio-oto-renal syndrome, CHARGE syndrome and Renal Tubular Acidosis.

Enlarged vestibular aqueducts can be bilateral or unilateral.

Hearing loss caused by large vestibular aqueduct syndrome is not inevitable, although people with the syndrome are at a much higher risk of developing hearing loss than the general population. Hearing loss is very likely.

Segmental odontomaxillary dysplasia is a painless, unilateral enlargement of the upper jaw. The cause is unknown, and the disease affects the jaws, teeth, and adjacent soft tissue. The premolars may be congenitally missing, and the primary teeth (baby teeth) may be smaller than usual. It is a relatively recent discovery.

This lesion is usually unilateral and affects several structures in the midbrain including:

It is caused by midbrain infarction as a result of occlusion of the paramedian branches of the posterior cerebral artery or of basilar bifurcation perforating arteries.

Although the finding itself is rare, MGDA can be associated with midline cranial defects and abnormal carotid circulation, such as carotid stenosis/aplasia or progressive vascular obstruction with collateralization (also known as moyamoya disease). The vascular defects may lead to ischemia, stroke, or seizures and so a finding of MGDA should be further investigated with radiographic imaging.

Incontinentia pigmenti achromians (also known as "hypomelanosis of Ito") is a cutaneous condition characterized by various patterns of bilateral or unilateral hypopigmentation following the lines of Blaschko. Though the consistency of the skin findings have led to the term "hypomelanosis of Ito", it actually refers to a group of disorders with various genetic causes including polyploidies and aneuploidies. Based upon the specifics of the genetic defect, the skin findings can be accompanied by a great range of systemic findings. These include central nervous system, ocular, and musculoskeletal defects. Nonetheless, the vast majority of cases are limited to the skin. As opposed to incontinentia pigmenti, hypomelanosis of Ito affects both genders equally.

Prominent ear, otapostasis or bat ear is an abnormally protruding human ear. It may be unilateral or bilateral. The concha is large with poorly developed antihelix and scapha. It is the result of malformation of cartilage during primitive ear development in intrauterine life. The deformity can be corrected anytime after 6 years. The surgery is preferably done at the earliest in order to avoid psychological distress. Correction by otoplasty involves changing the shape of the ear cartilage so that the ear is brought closer to the side of the head. The skin is not removed, but the shape of the cartilage is altered. The surgery does not affect hearing. It is done for cosmetic purposes only. The complications of the surgery, though rare, are keloid formation, hematoma formation, infection and asymmetry between the ears.

Patients who have malignant gliomas of the optic nerve have rapidly progressive, painful visual loss accompanied by signs of an optic neuropathy. Initial visual loss may be unilateral or bilateral (chiasmal involvement), but rapid progression to bilateral blindness and death are constant features. Depending on the initial location of the tumor, visual loss may be accompanied by exophthalmos, extraocular motility

Optic nerve melanocytoma does not usually produce symptoms or grow. If they slowly grow, optic nerve melanocytoma can produce afferent pupillary defects (30%), subretinal fluid (10%), and an enlarged blind spot (75%).

On fundoscopic exam, the optic disc may be swollen, atrophic, or even normal. Central retinal vein occlusion may occur.

If the tumor is next to the optic nerve, growth can compress the nerve and cause gradual loss of vision and unilateral proptosis. Dyschromatopsia may occur. Growth can also cause compressive vascular problems like central retinal vein occlusion. Lastly, growth also causes the tumor to exceed its blood supply. In these cases, necrotic areas form inside the tumor. Necrosis can (in turn) cause intraocular and rarely orbital inflammation.