Vision in the affected eye is impaired, the degree of which depends on the size of the defect, and typically affects the visual field more than visual acuity. Additionally, there is an increased risk of serous retinal detachment, manifesting in 1/3 of patients. If retinal detachment does occur, it is usually not correctable and all sight is lost in the affected area of the eye, which may or may not involve the macula.

ONH can be unilateral (in one eye) or bilateral (in both eyes), although it presents most often bilaterally (80%). Because the unilateral cases tend to have better vision, they are typically diagnosed at a later age than those with bilateral ONH. Visual acuity can range from no light perception to near-normal vision.

Children diagnosed with ONH generally present with vision problems which include nystagmus (involuntary movement of the eyes), which tends to develop at 1 to 3 months and/or strabismus (inability to align both eyes simultaneously), manifested during the first year of life.

The majority of children affected experience improvement in vision during the first few years of life, though the reason for this occurrence is unknown. There have been no reported cases of decline in vision due to ONH.

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.

The first noticeable signs of the syndrome usually do not appear until after the first twelve months of the child’s life. The child usually has severe balance issues as he or she learns to sit or walk, often leaning or tilting the head toward the good eye to correct the brain’s skewed perception of the world. Often the child will fall in the same direction while walking or run into objects that are placed on his or her blind side. Additionally, family members may notice a white reflex in the pupil of an affected child instead of the normal red reflex when taking photographs. The presence of this phenomenon is dependent on the degree of the coloboma, with larger colobomas more likely to manifest this particular phenomenon.

This anomaly must be confirmed through pupillary dilation and examination of the optic disc, as the symptoms alone do not constitute a diagnosis.

People with optic nerve colobomas live relatively normal lives. Although non-prescription glasses should be worn for eye protection, this syndrome does not usually prevent the individual from living a normal life, driving cars, playing sports, reading, etc. Certain activities, however, may be more difficult for patients with optic nerve colobomas due to a compromised view of the world. Like most other eye conditions, a diagnosis of optic nerve coloboma precludes a person from certain occupations.

More than 70% of children with ONH experience developmental delay, ranging from isolated focal defects to delay in all areas of development (global delay). Motor delay is most common (75%) and communication delay is least common (44%). Predictors of significantly delayed development include hypoplasia or agenesis of the corpus callosum and hypothyroidism. The absence of the septum pellucidum does not predict developmental delay. Delays may occur in unilateral (39%) as well as bilateral (78%) cases.

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

Sclerocornea is a congenital anomaly of the eye in which the cornea blends with sclera, having no clear-cut boundary. The extent of the resulting opacity varies from peripheral to total ("sclerocornea totalis"). The severe form is thought to be inherited in an autosomal recessive manner, but there may be another, milder form that is expressed in a dominant fashion. In some cases the patients also have abnormalities beyond the eye (systemic), such as limb deformities and craniofacial and genitourinary defects.

According to one tissue analysis performed after corneal transplantation, the sulfation pattern of keratan sulfate proteoglycans in the affected area is typical for corneal rather than scleral tissue.

Sclerocornea may be concurrent with cornea plana.

Lagophthalmos can arise from a malfunction of the facial nerve. Lagopthalmos can also occur in comatose patients having a decrease in orbicularis tone, in patients having palsy of the facial nerve (7th cranial nerve), in people with severe exophthalmos, and in people with severe skin disorders such as ichthyosis.

Today, lagophthalmos may arise after an overenthusiastic upper blepharoplasty. Blepharoplasty is an operation performed to remove excessive skin overlying the upper eyelid (suprapalpebral hooding) that often occurs with aging. This can appreciably improve the patient's appearance, and make the patient look younger. If, however, excessive skin is removed, the appearance is unnatural and "lagophthalmos" is one of the signs of such excessive skin removal.

Aphakia is the absence of the lens of the eye, due to surgical removal, a perforating wound or ulcer, or congenital anomaly. It causes a loss of accommodation, far sightedness (hyperopia), and a deep anterior chamber. Complications include detachment of the vitreous or retina, and glaucoma.

Babies are rarely born with aphakia. Occurrence most often results from surgery to remove congenital cataract (clouding of the eye's lens, which can block light from entering the eye and focusing clearly). Congenital cataracts usually develop as a result of infection of the fetus or genetic reasons. It is often difficult to identify the exact cause of these cataracts, especially if only one eye is affected.

People with aphakia have relatively small pupils and their pupils dilate to a lesser degree.

The most common malformation in patients with the syndrome is kidney hypodysplasia, which are small and underdeveloped kidneys, often leading to end-stage renal disease (ESRD). Estimates show approximately 10% of children with hypoplastic kidneys are linked to the disease. Many different histological abnormalities have been noted, including:

- decrease in nephron number associated with hypertrophy

- focal segmental glomerulosclerosis

- interstitial fibrosis and tubular atrophy

- multicystic dysplastic kidney

Up to one-third of diagnosed patients develop end stage kidney disease, which may lead to complete kidney failure.

Ocular disc dysplasia is the most notable ocular defect of the disease. An abnormal development in the optic stalk causes optic disc dysplasia, which is caused by a mutation in the "Pax2" gene. The nerve head typically resembles the morning glory disc anomaly, but has also been described as a coloboma. A coloboma is the failure to close the choroid fissure, which is the opening from the ventral side of the retina in the optic stalk. Despite the similarities with coloboma and morning glory anomaly, significant differences exist such that optic disc dysplasia cannot be classified as either one entity.

Optic disc dysplasia is noted by an ill-defined inferior excavation, convoluted origin of the superior retinal vessels, excessive number of vessels, infrapapillary pigmentary disturbance, and slight band of retinal elevation adjacent to the disk. Some patients have normal or near normal vision, but others have visual impairment associated with the disease, though it is not certain if this is due only to the dysplastic optic nerves, or a possible contribution from macular and retinal malformations. The retinal vessels are abnormal or absent, in some cases having small vessels exiting the periphery of the disc. There is a great deal of clinical variability.

The generalized, common presentation for this broad and inclusive group of diseases is painless, bilateral loss of visual acuity and pallor of the optic disc accompanied with varying degrees of dyschromatopsia and central/cecocentral scatomas. On examination the papillary response may be sluggish to light, one would not expect to find an afferent papillary defect. This is because optic neuropathies are often bilateral and symmetric. The optic disc may be mildly hyperemic with small splinter hemorrhages on or around the disc. Optic atrophy may early on be non-existent and only later become mild. In later stages the optic atrophy is severe and this indicates less opportunity for recovery.

The duration of onset can vary between immediate and insidious, owing to the specific etiology. Two key features may be helpful in distinguishing acquired from inherited optic neuropathies: absence of a family history and simultaneous involvement of both eyes; the former more commonly characterized by these two features.

Ophthalmoparesis can involve any or all of the extraocular muscles, which include the superior recti, inferior recti, medial recti, lateral recti, inferior oblique and superior oblique muscles.

It can also be classified by the directions of affected movements, e.g. "vertical ophthalmoparesis".

Axenfeld syndrome (also known as Axenfeld-Rieger syndrome or Hagedoom syndrome) is a rare autosomal dominant disorder, which affects the development of the teeth, eyes, and abdominal region.

Without the focusing power of the lens, the eye becomes very farsighted. This can be corrected by wearing glasses, contact lenses, or by implant of an artificial lens. Artificial lenses are described as "pseudophakic." Also, since the lens is responsible for adjusting the focus of vision to different lengths, patients with aphakia have a total loss of accommodation.

Some individuals have said that they perceive ultraviolet light, invisible to those with a lens, as whitish blue or whitish-violet.

Lagophthalmos is the inability to close the eyelids completely.

Blinking covers the eye with a thin layer of tear fluid, thereby promoting a moist environment necessary for the cells of the exterior part of the eye. The tears also flush out foreign bodies and wash them away. This is crucial to maintain lubrication and proper eye health. If this process is impaired, as in lagophthalmos, the eye can suffer abrasions and infections. Lagopthalmos leads to corneal drying and ulceration.

The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near-centered tasks. They may include, but are not limited to, diplopia (double vision), asthenopia (eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue,

headache, and abnormal postural adaptation, among others. In some cases, difficulty with making eye contact have been noted as a complaint amongst sufferers.

Note that some Internet resources confuse convergence and divergence dysfunction, reversing them.

Pathological nystagmus is characterized by "excessive drifts of stationary retinal images that degrades vision and may produce illusory motion of the seen world: oscillopsia (an exception is congenital nystagmus)".

When nystagmus occurs without fulfilling its normal function, it is pathologic (deviating from the healthy or normal condition). Pathological nystagmus is the result of damage to one or more components of the vestibular system, including the semicircular canals, otolith organs, and the vestibulocerebellum.

Pathological nystagmus generally causes a degree of vision impairment, although the severity of such impairment varies widely. Also, many blind people have nystagmus, which is one reason that some wear dark glasses.

Physiological nystagmus is a form of involuntary eye movement that is part of the vestibulo-ocular reflex (VOR), characterized by alternating smooth pursuit in one direction and saccadic movement in the other direction.

Convergence insufficiency or convergence disorder is a sensory and neuromuscular anomaly of the binocular vision system, characterized by a reduced ability of the eyes to turn towards each other, or sustain convergence.

Typically not diagnosed until late childhood or later, Bonnet–Dechaume–Blanc syndrome usually presents itself with a combination of central nervous system features (midbrain), ophthalmic features (retina), and facial features. The degree of expression of the syndrome's components varies both clinically and structurally. Common symptoms that lead to diagnosis are headaches, retro-orbital pain and hemianopia.

The ophthalmic features of the Bonnet–Dechaume–Blanc syndrome occur as retinal arteriovenous malformation (AVMs). There are three categories of AVMs that are categorized depending on the severity of the malformation. The first category consists of the patient having small lesions that usually are asymptomatic. The second category, more severe than the first, is when the patient’s malformation is missing a connecting capillary. The missing capillary is meant to serve as a link between an artery and a vein; without it, edemas, hemorrhages, and visual impairments can result. Category three, the most severe, occurs when the patient’s malformations are so severe that the dilated vessels cause no distinction between artery and vein. When the symptoms are this severe, the patient has a significantly increased risk of developing vision loss. Since the retinal lesions categorized vary from large vascular malformations that affect a majority of the retina to malformations that are barely visible, the lesions cause a wide range of symptoms including decrease in visual sharpness, proptosis, pupillary defects, optic degeneration and visual field defects. The most common type of visual field impairment due to AVMs is homonymous hemianopia. Homonymous hemianopia typically presents unilaterally, but bilateral cases have been reported as well.

The extent of the central nervous system (CNS) features/symptoms of Bonnet–Dechaume–Blanc syndrome is highly dependent of the location of the cerebral AVMs and the extent of the malformation. The most common symptom affecting the CNS is an intracranial hemangioma in the midbrain. Along with hemangiomas, the malformations result in severe headaches, cerebral hemorrhages, vomiting, meningism, seizures, acute strokes or progressive neurological deficits due to acute or chronic ischaemia caused by arteriovenous shunting.

The distinguishable facial features that result from Bonnet–Dechaume–Blanc syndrome vary from case to case. A person showing signs of the syndrome may display faint skin discoloration, nevi and angiomas of the skin. Some patients with this disorder also present with high flow arteriovenous malformations of the maxillofacial or mandibular (jaw) regions. Another facial indicator of this disease is malformations affecting the frontal and/or maxillary sinuses.

Signs that are found in patients on the affected side of the face include

- partial ptosis

- upside-down ptosis (slight elevation of the lower lid)

- anhidrosis

- miosis

- pseudoenophthalmos (the impression that the eye is sunken, caused by a narrow palpebral aperture)

- pupillary dilation lag

- loss of ciliospinal reflex

- bloodshot conjunctiva, depending on the site of lesion.

- unilateral straight hair (in congenital Horner's syndrome); the hair on the affected side may be straight in some cases.

- heterochromia iridum (in congenital Horner's syndrome)

Interruption of sympathetic pathways leads to several implications. It inactivates the dilator muscle and thereby produces miosis. It inactivates the superior tarsal muscle which produces ptosis. It inactivates the orbitalis muscle which produces the effect of enophthalmos. It also reduces sweat secretion in the face.

Sometimes there is flushing on the affected side of the face due to dilation of blood vessels under the skin. The pupil's light reflex is maintained as this is controlled via the parasympathetic nervous system.

In children, Horner's syndrome sometimes leads to heterochromia, a difference in eye color between the two eyes. This happens because a lack of sympathetic stimulation in childhood interferes with melanin pigmentation of the melanocytes in the superficial stroma of the iris.

In veterinary medicine, signs can include partial closure of the third eyelid, or nictitating membrane.

Horner's syndrome is a combination of symptoms that arises when a group of nerves known as the sympathetic trunk is damaged. The signs and symptoms occur on the same side as the lesion of the sympathetic trunk. It is characterized by miosis (a constricted pupil), partial ptosis (a weak, droopy eyelid), apparent anhidrosis (decreased sweating), with or without enophthalmos (inset eyeball).

The nerves of the sympathetic trunk arise from the spinal cord in the chest, and from there ascend to the neck and face. The nerves are part of the sympathetic nervous system, a division of the autonomic (or involuntary) nervous system. Once the syndrome has been recognized, medical imaging and response to particular eye drops may be required to identify the location of the problem and the underlying cause.

Neurological causes for photophobia include:

- Autism spectrum disorders

- Chiari malformation

- Occipital Neuralgia

- Dyslexia

- Encephalitis including Myalgic encephalomyelitis aka Chronic fatigue syndrome

- Meningitis

- Trigeminal disturbance causes central sensitization (hence, multiple other associated hypersensitivities. Causes can be bad bite, infected tooth, etc.

- Subarachnoid haemorrhage

- Tumor of the posterior cranial fossa

Enophthalmos is the posterior displacement of the eyeball within the orbit due to changes in the volume of the orbit (bone) relative to its contents (the eyeball and orbital fat), or loss of function of the orbitalis muscle. It should not be confused with its opposite, exophthalmos, which is the anterior displacement of the eye.

It may be a congenital anomaly, or be acquired as a result of trauma (such as in a blowout fracture of the orbit), Horner's syndrome (apparent enophthalmos due to ptosis), Marfan syndrome, Duane's syndrome, silent sinus syndrome or phthisis bulbi.