Disorders of ocular muscles, binocular movement, accommodation and refraction

Brown's syndrome is a rare form of strabismus characterized by limited elevation of the affected eye.

Heterophoria is an eye condition in which the directions that the eyes are pointing at rest position, when not performing binocular fusion, are not the same as each other, or, "not straight".

Internuclear ophthalmoplegia (INO) is a disorder of conjugate lateral gaze in which the affected eye shows impairment of adduction.

Kearns–Sayre syndrome (abbreviated KSS), also known as oculocraniosomatic disorder or oculocraniosomatic neuromuscular disorder with ragged red fibers, is a mitochondrial myopathy with a typical onset before 20 years of age.

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.

Cyclotropia is a form of strabismus in which, compared to the correct positioning of the eyes, there is a torsion of one eye (or both) about the eye's visual axis.

Esophoria is a condition characterised by inward deviation of the eye, usually due to extra-ocular muscle imbalance.

Fourth cranial nerve palsy also known as Trochlear nerve palsy, is a condition affecting Cranial Nerve 4 (IV), the Trochlear Nerve, which is one of the Cranial Cranial Nerves that causes weakness or paralysis to the Superior Oblique muscle superior oblique muscle that it innervates.

Hypertropia is a condition of misalignment of the eyes (strabismus), whereby the visual axis of one eye is higher than the fellow fixating eye.

Duane syndrome is a congenital rare type of strabismus most commonly characterized by the inability of the eye to move outwards.

Astigmatism is a type of refractive error in which the eye does not focus light evenly on the retina.

Presbyopia is a condition associated with aging of the eye that results in progressively worsening ability to focus clearly on close objects.

Refractive error, also known as refraction error, is a problem with focusing of light on the retina due to the shape of the eye.

Chronic progressive external ophthalmoplegia (CPEO), also known as progressive external ophthalmoplegia (PEO), is a type of eye disorder characterized by slowly progressive inability to move the eyes and eyebrows.

Esotropia is a form of strabismus in which one or both eyes turns inward.

Ophthalmoparesis or ophthalmoplegia refers to weakness (-paresis) or paralysis (-plegia) of one or more extraocular muscles which are responsible for eye movements.

Exophoria is a form of heterophoria in which there is a tendency of the eyes to deviate outward.

Oculomotor nerve palsy or third nerve palsy is an eye condition resulting from damage to the third cranial nerve or a branch thereof.

Sixth nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI (the abducens nerve), which is responsible for causing contraction of the lateral rectus muscle to abduct (i.e., turn out) the eye.

Strabismus, also called crossed eyes, is a condition in which the eyes do not properly align with each other when looking at an object.

Exotropia is a form of strabismus where the eyes are deviated outward.

Aniseikonia is an ocular condition where there is a significant difference in the perceived size of images.

Anisometropia is the condition in which the two eyes have unequal refractive power.

Far-sightedness, also known as hyperopia, is a condition of the eye where light focuses behind, instead of on, the retina.

Near-sightedness, also known as short-sightedness and myopia, is a condition of the eye where light focuses in front, instead of on the retina.

For acquired fourth nerve palsy, see fourth nerve palsy Congenital fourth nerve palsy is a condition present at birth characterized by a vertical misalignment of the eyes due to a weakness or paralysis of the superior oblique muscle.