The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina. It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil. The size of the pupil is controlled by the iris, and varies depending on many factors, the most significant being the amount of light in the environment. The term "pupil" was coined by Gerard of Cremona.
General paresis, also known as general paralysis of the insane (GPI), paralytic dementia, or syphilitic paresis is a severe neuropsychiatric disorder, classified as an organic mental disorder, and is caused by late-stage syphilis and the chronic meningoencephalitis and cerebral atrophy that are associated with this late stage of the disease when left untreated. GPI differs from mere paresis, as mere paresis can result from multiple other causes and usually does not affect cognitive function. Degenerative changes caused by GPI are associated primarily with the frontal and temporal lobar cortex. The disease affects approximately 7% of individuals infected with syphilis, and is far more common in developing countries where fewer options for timely treatment are available. It is more common among men.
Mydriasis is the dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response. Non-physiological causes of mydriasis include disease, trauma, or the use of certain types of drug. It may also be of unknown cause.
Tabes dorsalis is a late consequence of neurosyphilis, characterized by the slow degeneration of the neural tracts primarily in the dorsal root ganglia of the spinal cord. These patients have lancinating nerve root pain which is aggravated by coughing, and features of sensory ataxia with ocular involvement.
The ankle jerk reflex, also known as the Achilles reflex, occurs when the Achilles tendon is tapped while the foot is dorsiflexed. It is a type of stretch reflex that tests the function of the gastrocnemius muscle and the nerve that supplies it. A positive result would be the jerking of the foot towards its plantar surface. Being a deep tendon reflex, it is monosynaptic. It is also a stretch reflex. These are monosynaptic spinal segmental reflexes. When they are intact, integrity of the following is confirmed: cutaneous innervation, motor supply, and cortical input to the corresponding spinal segment.
The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation of vision to various levels of lightness/darkness. A greater intensity of light causes the pupil to constrict, whereas a lower intensity of light causes the pupil to dilate. Thus, the pupillary light reflex regulates the intensity of light entering the eye. Light shone into one eye will cause both pupils to constrict.
Miosis, or myosis, is excessive constriction of the pupil. The opposite condition, mydriasis, is the dilation of the pupil. Anisocoria is the condition of one pupil being more dilated than the other.
In neuroanatomy, the optic tract is a part of the visual system in the brain. It is a continuation of the optic nerve that relays information from the optic chiasm to the ipsilateral lateral geniculate nucleus (LGN), pretectal nuclei, and superior colliculus.
The ciliary ganglion is a parasympathetic ganglion located just behind the eye in the posterior orbit. It is 1–2 mm in diameter and in humans contains approximately 2,500 neurons. The ganglion contains postganglionic parasympathetic neurons. These neurons supply the pupillary sphincter muscle, which constricts the pupil, and the ciliary muscle which contracts to make the lens more convex. Both of these muscles are involuntary since they are controlled by the parasympathetic division of the autonomic nervous system.
Adie syndrome, also known as Holmes–Adie syndrome, is a neurological disorder characterized by a tonically dilated pupil that reacts slowly to light but shows a more definite response to accommodation. It is frequently seen in females with absent knee or ankle jerks and impaired sweating.
Anisocoria is a condition characterized by an unequal size of the eyes' pupils. Affecting up to 20% of the population, anisocoria is often entirely harmless, but can be a sign of more serious medical problems.
Parinaud's syndrome is a constellation of neurological signs indicating injury to the dorsal midbrain. More specifically, compression of the vertical gaze center at the rostral interstitial nucleus of medial longitudinal fasciculus (riMLF).
Neurosyphilis is the infection of the central nervous system in a patient with syphilis. In the era of modern antibiotics, the majority of neurosyphilis cases have been reported in HIV-infected patients. Meningitis is the most common neurological presentation in early syphilis. Tertiary syphilis symptoms are exclusively neurosyphilis, though neurosyphilis may occur at any stage of infection.
A pinealoma is a tumor of the pineal gland, a part of the brain that produces melatonin. If a pinealoma destroys the cells of the pineal gland in a child, it can cause precocious puberty.
A relative afferent pupillary defect (RAPD), also known as a Marcus Gunn pupil, is a medical sign observed during the swinging-flashlight test whereupon the patient's pupils excessively dilate when a bright light is swung from the unaffected eye to the affected eye. The affected eye still senses the light and produces pupillary sphincter constriction to some degree, albeit reduced.
Douglas Moray Cooper Lamb Argyll Robertson FRSE, FRCSEd LLD was a Scottish ophthalmologist and surgeon. He introduced physostigmine into ophthalmic practice and the Argyll Robertson pupil is named after him. He was president of the Royal College of Surgeons of Edinburgh.
Henri Parinaud was a French ophthalmologist and neurologist, most noted for his work in the field of neuro-ophthalmology.
Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve.
Meningeal syphilis is a chronic form of syphilis infection that affects the central nervous system. Treponema pallidum, a spirochate bacterium, is the main cause of syphilis, which spreads drastically throughout the body and can infect all its systems if not treated appropriately. Treponema pallidum is the main cause of the onset of meningeal syphilis and other treponemal diseases, and it consists of a cytoplasmic and outer membrane that can cause a diverse array of diseases in the central nervous system and brain.
In ophthalmology, accommodative excess occurs when an individual uses more than normal accommodation for performing certain near work. Accommodative excess has traditionally been defined as accommodation that is persistently higher than expected for the patient's age. Modern definitions simply regard it as an inability to relax accommodation readily. Excessive accommodation is seen in association with excessive convergence also.
