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".

Parinaud's Syndrome is a cluster of abnormalities of eye movement and pupil dysfunction, characterized by:

1. Paralysis of upgaze: Downward gaze is usually preserved. This vertical palsy is supranuclear, so doll's head maneuver should elevate the eyes, but eventually all upward gaze mechanisms fail.

2. Pseudo-Argyll Robertson pupils: Accommodative paresis ensues, and pupils become mid-dilated and show light-near dissociation.

3. Convergence-Retraction nystagmus: Attempts at upward gaze often produce this phenomenon. On fast up-gaze, the eyes pull in and the globes retract. The easiest way to bring out this reaction is to ask the patient to follow down-going stripes on an optokinetic drum.

4. Eyelid retraction (Collier's sign)

5. Conjugate down gaze in the primary position: "setting-sun sign". Neurosurgeons see this sign most commonly in patients with failed hydrocephalus shunts.

It is also commonly associated with bilateral papilledema. It has less commonly been associated with spasm of accommodation on attempted upward gaze, pseudoabducens palsy (also known as thalamic esotropia) or slower movements of the abducting eye than the adducting eye during horizontal saccades, see-saw nystagmus and associated ocular motility deficits including skew deviation, oculomotor nerve palsy, trochlear nerve palsy and internuclear ophthalmoplegia.

Ophthalmoparesis or ophthalmoplegia refers to weakness (-paresis) or paralysis (-plegia) of one or more extraocular muscles which are responsible for eye movements. It is a physical finding in certain neurologic, ophthalmologic, and endocrine disease.

Internal ophthalmoplegia means involvement limited to the pupillary sphincter and ciliary muscle. External ophthalmoplegia refers to involvement of only the extraocular muscles. Complete ophthalmoplegia indicates involvement of both.

The one and a half syndrome is a rare weakness in eye movement affecting both eyes, in which one cannot move laterally at all, and the other can move in only one lateral direction (inward or outward). More formally, it is characterized by ""a conjugate horizontal gaze palsy in one direction and an internuclear ophthalmoplegia in the other"". The most common manifestation of this unusual syndrome is limitation of horizontal eye movement to abduction (moving away from the midline) of one eye (e.g. right eye in the diagram on the right) with no horizontal movement of the other eye (e.g. left eye in the diagram on the right). Nystagmus is also present when the eye on the opposite side of the lesion is abducted. Convergence is classically spared as cranial nerve III (oculomotor nerve) and its nucleus is spared bilaterally.

CPEO is a slowly progressing disease. It may begin at any age and progresses over a period of 5–15 years. The first presenting symptom of ptosis is often unnoticed by the patient until the lids droop to the point of producing a visual field defect. Often, patients will tilt the head backwards to adjust for the slowly progressing ptosis of the lids. In addition, as the ptosis becomes complete, the patients will use the frontalis (forehead) muscle to help elevate the lids. The ptosis is typically bilateral, but may be unilateral for a period of months to years before the fellow lid becomes involved.

Ophthalmoplegia or the inability or difficulty to move the eye is usually symmetrical. As such, double vision is sometimes a complaint of these patients. The progressive ophthalmoplegia is often unnoticed till decreased ocular motility limits peripheral vision. Often someone else will point out the ocular disturbance to the patient. Patients will move their heads to adjust for the loss of peripheral vision caused by inability to abduct or adduct the eye. All directions of gaze are affected; however, downward gaze appears to be best spared. This is in contrast to progressive supranuclear palsy (PSP), which typically affects vertical gaze and spares horizontal gaze.

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.

CPEO is a rare disease that may affect those of all ages, but typically manifests in the young adult years. CPEO is the most common manifestation of mitochondrial myopathy, occurring in an estimated two-thirds of all cases of mitochondrial myopathy. Patients typically present with ptosis (drooping eyelids). Other diseases like Graves' disease, myasthenia gravis and glioma that may cause an external ophthalmoplegia must be ruled out.

Internuclear ophthalmoplegia (INO) is a disorder of conjugate lateral gaze in which the affected eye shows impairment of adduction. When an attempt is made to gaze contralaterally (relative to the affected eye), the affected eye adducts minimally, if at all. The contralateral eye abducts, however with nystagmus. Additionally, the divergence of the eyes leads to horizontal diplopia. That is, if the right eye is affected the patient will "see double" when looking to the left, seeing two images side-by-side. Convergence is generally preserved.

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.

The disorder is caused by injury or dysfunction in the medial longitudinal fasciculus (MLF), a heavily myelinated tract that allows conjugate eye movement by connecting the paramedian pontine reticular formation (PPRF)-abducens nucleus complex of the contralateral side to the oculomotor nucleus of the ipsilateral side.

In young patients with bilateral INO, multiple sclerosis is often the cause. In older patients with one-sided lesions a stroke is a distinct possibility. Other causes are possible.

Conjugate gaze palsies can be classified into palsies affecting horizontal gaze and vertical gaze.

A patient may be diagnosed with a conjugate gaze palsy by a physician performing a number of tests to examine the patient's eye movement abilities. In most cases, the gaze palsy can simply be seen by inability to move both eyes in one direction. However, sometimes a patient exhibits an abduction nystagmus in both eyes, indicating evidence of a conjugate gaze palsy. A nystagmus is a back and forth "jerk" of the eye when attempting to hold a gaze in one direction.

The most common finding is oculomotor nerve dysfunction leading to ophthalmoplegia. This is often accompanied by ophthalmic nerve dysfunction, leading to hypoesthesia of the upper face. The optic nerve may eventually be involved, with resulting visual impairment.

Symptoms are usually limited to one side of the head, and in most cases the individual affected will experience intense, sharp pain and paralysis of muscles around the eye. Symptoms may subside without medical intervention, yet recur without a noticeable pattern.

In addition, affected individuals may experience paralysis of various facial nerves and drooping of the upper eyelid (ptosis). Other signs include double vision, fever, chronic fatigue, vertigo or arthralgia. Occasionally the patient may present with a feeling of protrusion of one or both eyeballs (exophthalmos).

This produces ipsilateral horizontal gaze palsy and facial nerve palsy and contralateral hemiparesis, hemisensory loss, and internuclear ophthalmoplegia.

Orbital apex syndrome, also known as Jacod syndrome, is a collection of cranial nerve deficits associated with a mass lesion near the apex of the orbit of the eye. This syndrome is a separate entity from Rochon–Duvigneaud syndrome, which occurs due to a lesion immediately anterior to the orbital apex. Most commonly optic nerve is involved.

Foville's syndrome is caused by the blockage of the perforating branches of the basilar artery in the region of the brainstem known as the pons. Most frequently caused by vascular disease or tumors involving the dorsal pons.[3]

Structures affected by the infarct are the PPRF, nuclei of cranial nerves VI and VII, corticospinal tract, medial lemniscus, and the medial longitudinal fasciculus. There's involvement of the fifth to eighth cranial nerves, central sympathetic fibres (Horner syndrome) and horizontal gaze palsy.[3]

Individuals with KSS present initially in a similar way to those with typical CPEO. Onset is in the first and second decades of life.

The first symptom of this disease is a unilateral ptosis, or difficulty opening the eyelids, that gradually progresses to a bilateral ptosis. As the ptosis worsens, the individual commonly extends their neck, elevating their chin in an attempt to prevent the eyelids from occluding the visual axis. Along with the insidious development of ptosis, eye movements eventually become limited causing a person to rely more on turning the head side to side or up and down to view objects in the peripheral visual field.

KSS results in a pigmentation of the retina, primarily in the posterior fundus. The appearance is described as a "salt-and-pepper" appearance. There is diffuse depigmentation of the retinal pigment epithelium with the greatest effect occurring at the macula. This is in contrast to retinitis pigmentosa where the pigmentation is peripheral. The appearance of the retina in KSS is similar to that seen in myotonic dystrophy type 1 (abbreviated DM1). Modest night-blindness can be seen in patients with KSS. Visual acuity loss is usually mild and only occurs in 40–50% of patients.

Tolosa–Hunt syndrome (THS) is a rare disorder characterized by severe and unilateral headaches with orbital pain, along with weakness and paralysis (ophthalmoplegia) of certain eye muscles (extraocular palsies).

In 2004, the International Headache Society provided a definition of the diagnostic criteria which included granuloma.

Enophthalmos (recession of the eyeball within the orbit) is the most common eye abnormality observed in Parry–Romberg syndrome. It is caused by a loss of subcutaneous tissue around the orbit. Other common findings include drooping of the eyelid (ptosis), constriction of the pupil (miosis), redness of the conjunctiva, and decreased sweating (anhidrosis) of the affected side of the face. Collectively, these signs are referred to as Horner's syndrome. Other ocular abnormalities include ophthalmoplegia (paralysis of one or more of the extraocular muscles) and other types of strabismus, uveitis, and heterochromia of the iris.

Initial facial changes usually involve the area of the face covered by the temporal or buccinator muscles. The disease progressively spreads from the initial location, resulting in atrophy of the skin and its adnexa, as well as underlying subcutaneous structures such as connective tissue, (fat, fascia, cartilage, bones) and/or muscles of one side of the face. The mouth and nose are typically deviated towards the affected side of the face.

The process may eventually extend to involve tissues between the nose and the upper corner of the lip, the upper jaw, the angle of the mouth, the area around the eye and brow, the ear, and/or the neck. The syndrome often begins with a circumscribed patch of scleroderma in the frontal region of the scalp which is associated with a loss of hair and the appearance of a depressed linear scar extending down through the midface on the affected side. This scar is referred to as a "coup de sabre" lesion because it resembles the scar of a wound made by a sabre, and is indistinguishable from the scar observed in frontal linear scleroderma.

In 20% of cases, the hair and skin overlying affected areas may become hyperpigmented or hypopigmented with patches of unpigmented skin. In up to 20% of cases the disease may involve the ipsilateral (on the same side) or contralateral (on the opposite side) neck, trunk, arm, or leg. The cartilage of the nose, ear and larynx can be involved. The disease has been reported to affect both sides of the face in 5-10% of the cases.

Symptoms and physical findings usually become apparent during the first or early during the second decade of life. The average age of onset is nine years of age, and the majority of individuals experience symptoms before 20 years of age. The disease may progress for several years before eventually going into remission (abruptly ceasing).

Neurological causes include:

- Optic neuritis

- Compressive optic neuropathies

- Papilledema: "The underlying mechanism for visual obscurations in all of these patients appear to be transient ischemia of the optic nerve head consequent to increased tissue pressure. Axonal swelling, intraneural masses, and increased influx of interstitial fluid may all contribute to increases in tissue pressure in the optic nerve head. The consequent reduction in perfusion pressure renders the small, low-pressure vessels that supply the optic nerve head vulnerable to compromise. Brief fluctuations in intracranial or systemic blood pressure may then result in transient loss of function in the eyes." Generally, this transient visual loss is also associated with a headache and optic disk swelling.

- Multiple Sclerosis can cause amaurosis fugax due to a unilateral conduction block, which is a result of demyelination and inflammation of the optic nerve, and "...possibly by defects in synaptic transmission and putative circulating blocking factors."

- Migraine

- Pseudotumor cerebri

- Intracranial tumor

- Psychogenic

The experience of amaurosis fugax is classically described as a temporary loss of vision in one or both eyes that appears as a black "curtain coming down vertically into the field of vision in one eye;" however, this altitudinal visual loss is relatively uncommon. In one study, only 23.8 percent of patients with transient monocular vision loss experienced the classic "curtain" or "shade" descending over their vision. Other descriptions of this experience include a monocular blindness, dimming, fogging, or blurring. Total or sectorial vision loss typically lasts only a few seconds, but may last minutes or even hours. Duration depends on the cause of the vision loss. Obscured vision due to papilledema may last only seconds, while a severely atherosclerotic carotid artery may be associated with a duration of one to ten minutes. Certainly, additional symptoms may be present with the amaurosis fugax, and those findings will depend on the cause of the transient monocular vision loss.

The most common sign at presentation is leukocoria (abnormal white reflection of the retina). Symptoms typically begin as blurred vision, usually pronounced when one eye is closed (due to the unilateral nature of the disease). Often the unaffected eye will compensate for the loss of vision in the other eye; however, this results in some loss of depth perception and parallax. Deterioration of sight may begin in either the central or peripheral vision. Deterioration is likely to begin in the upper part of the vision field as this corresponds with the bottom of the eye where blood usually pools. Flashes of light, known as photopsia, and floaters are common symptoms. Persistent color patterns may also be perceived in the affected eye. Initially, these may be mistaken for psychological hallucinations, but are actually the result of both retinal detachment and foreign fluids mechanically interacting with the photoreceptors located on the retina.

One early warning sign of Coats' disease is yellow-eye in flash photography. Just as the red-eye effect is caused by a reflection off blood vessels in the back of a normal eye, an eye affected by Coats' will glow yellow in photographs as light reflects off cholesterol deposits. Children with yellow-eye in photographs are typically advised to immediately seek evaluation from an optometrist or ophthalmologist, who will assess and diagnose the condition and refer to a vitreo-retinal specialist.

Coats' disease itself is painless. Pain may occur if fluid is unable to drain from the eye properly, causing the internal pressure to swell, resulting in painful glaucoma.