myasthenia gravis is an autoimmune condition that causes muscle weakness that often worsens with activity and improves with rest. It is commonly discussed in eye care because it can cause droopy eyelids (ptosis) and double vision (diplopia). It is also used as a medical diagnosis in neurology and internal medicine when weakness affects other body muscles.
ocular myasthenia is a form of myasthenia gravis that affects the eyes and eyelids. It commonly causes fluctuating droopy eyelids (ptosis) and double vision (diplopia). It is used as a clinical term in eye clinics and neurology to describe eye-limited neuromuscular weakness. It is evaluated when symptoms vary during the day or worsen with fatigue.
optic chiasm compression means pressure on the optic chiasm, the crossing point of the optic nerves. It can interrupt visual signals traveling from the eyes to the brain. It is commonly discussed in eye clinics when visual field tests are abnormal. It is also a key topic in neuro-ophthalmology, neurology, endocrinology, and neurosurgery.
A pituitary adenoma is a usually benign (non-cancerous) tumor that arises from the pituitary gland. The pituitary gland sits at the base of the brain, just below the optic nerves where they cross. The term pituitary adenoma is commonly used in neurology, endocrinology, neurosurgery, and eye care. In ophthalmology, it matters because it can affect vision by pressing on nearby visual pathways.
compressive optic neuropathy is vision loss or optic nerve dysfunction caused by physical pressure on the optic nerve. The optic nerve is the “cable” that carries visual signals from the eye to the brain. Compression can come from nearby swelling, abnormal anatomy, or a growth in the orbit (eye socket) or brain. The term is commonly used in eye clinics and neuro-ophthalmology to describe a cause of gradual or sometimes rapid vision decline.
Adie tonic pupil is an eye finding where one pupil is larger and reacts slowly to light. It happens because the nerve supply that normally constricts the pupil and helps focusing is partly disrupted. Many people notice it as uneven pupil size (anisocoria), light sensitivity, or blur when reading. The term is commonly used in ophthalmology and optometry to describe a characteristic pattern on pupil testing.
Horner syndrome is a pattern of eye and facial findings caused by reduced sympathetic nerve signals to one side of the face and eye. It commonly shows up as a droopy upper eyelid and a smaller pupil on the same side. It is used in eye care and neurology as a clinical clue that helps localize where a nerve pathway may be disrupted. It is a finding, not a single disease, and it can have many possible causes.
internuclear ophthalmoplegia is a disorder of coordinated eye movement that usually causes double vision and difficulty moving the eyes together. It happens when a specific brainstem pathway that links the eye-movement nerves is disrupted. Clinicians most often discuss it in neuro-ophthalmology and neurology because it helps localize where a problem is in the nervous system. It is commonly identified during an eye movement exam rather than through a single standalone “test.”
The term abducens palsy describes weakness or paralysis of the eye movement controlled by the sixth cranial nerve. It commonly causes trouble moving one eye outward and can lead to double vision. Clinicians use it in eye care and neurology to describe a specific pattern of eye misalignment. It is used in clinics, emergency settings, and inpatient care when evaluating new eye movement symptoms.
sixth nerve palsy is weakness or loss of function of the sixth cranial nerve (the abducens nerve). It affects how one eye moves outward (away from the nose). It commonly causes horizontal double vision and an eye that turns inward. The term is used in eye clinics and neurology settings to describe a specific eye-movement problem and its causes.
trochlear palsy is a problem with the fourth cranial nerve, which helps control one of the eye’s moving muscles. It commonly causes vertical double vision and a head tilt that feels “needed” to see clearly. The term is used in ophthalmology, optometry, neurology, and emergency care when evaluating binocular vision symptoms. It can be present from birth or acquired later in life.
fourth nerve palsy is a condition where the fourth cranial nerve (the trochlear nerve) does not work normally. It affects the superior oblique eye muscle, which helps control vertical movement and eye rotation. People often notice vertical or “tilted” double vision and may tilt their head to compensate. The term is commonly used in ophthalmology, optometry, neurology, and emergency care when evaluating eye misalignment.
oculomotor palsy is weakness or paralysis of the third cranial nerve (the oculomotor nerve). It can affect eyelid position, eye movements, and sometimes the pupil. It is commonly used as a clinical diagnosis in ophthalmology, optometry, and neurology.
third nerve palsy is a condition where the third cranial nerve (the oculomotor nerve) does not work normally. It can affect eyelid position, eye movements, and sometimes the pupil. It is commonly discussed in eye care, neurology, and emergency settings because the causes range from mild to serious. Clinicians use the term to describe a recognizable pattern of eye findings that helps guide evaluation.
cortical visual impairment is reduced or inconsistent vision caused by how the brain processes visual information. It can occur even when the eyes look structurally healthy on examination. It is commonly discussed in pediatric ophthalmology, neuro-ophthalmology, and low-vision care. It is also used in educational and rehabilitation settings to describe brain-based visual needs.
quadrantanopia is a visual field loss affecting one quarter of what a person can see. It is a type of “visual field defect,” meaning vision is missing in a specific area while the rest may be normal. It is most commonly discussed in neuro-ophthalmology because it often reflects changes in the brain’s visual pathways. Clinicians use the pattern of loss to help describe symptoms and localize where a problem may be occurring.
homonymous hemianopia is a pattern of vision loss affecting the same side of the visual world in both eyes. It happens when the brain’s visual pathways are disrupted, not because the eyes themselves are damaged. Clinicians use this term to describe and document visual field (side vision) loss found on testing. It is commonly discussed in neuro-ophthalmology, stroke care, neurology, optometry, and vision rehabilitation.
bitemporal hemianopia is a visual field pattern where the outer (temporal) half of vision is missing in both eyes. It is a type of “hemianopia,” meaning loss of half of the visual field. It most often points to a problem near the optic chiasm, where key optic nerve fibers cross. Clinicians commonly use the term when interpreting visual field tests and planning further evaluation.
A cecocentral scotoma is a vision “blind spot” or dim area that involves both central vision and the normal blind spot. It is a visual field pattern that can be measured on formal vision testing. People may notice missing, blurred, or washed-out detail when looking straight ahead. Clinicians most often use the term in visual field interpretation and optic nerve or macular evaluations.
An altitudinal defect is a pattern of vision loss affecting either the upper half or the lower half of the visual field. It is most often identified on visual field testing (perimetry) and described in clinical notes. Clinicians use it as a clue to where and how the visual pathway may be affected. It is commonly discussed in conditions involving the optic nerve or retinal circulation.