What is the Marcus Gunn pupil?

Marcus Gunn pupil (MGP) is the term given to an abnormal pupil showing aberrant pupillary response in certain ocular disorders. In literature, the term is often used synonymously with Marcus Gunn phenomenon or relative afferent pupillary defect (RAPD). [1] After exposure to bright light, a normal pupil constricts.

What causes a Marcus Gunn pupil?

Different types of cerebrovascular disease include strokes, aneurysms, and vascular malformations. Retinal diseases or damage can also cause Marcus Gunn pupil. These conditions include retinal detachment, retinal infections, and ischemic retinal disease.

When do you see a Marcus Gunn pupil?

A Marcus Gunn pupil is seen, among other conditions, in optic neuritis. It is also common in retrobulbar optic neuritis due to multiple sclerosis but only for 3–4 weeks, until the visual acuity begins to improve in 1–2 weeks and may return to normal.

How is Marcus Gunn pupil detected?

The Marcus Gunn pupil can be detected by swinging a flashlight between both eyes. Of course, normally, if you flash light in one eye, both pupils will constrict.

What causes Argyll Robertson pupil?

Argyll Robertson pupil is found in late-stage syphilis, a disease caused by the spirochete Treponema pallidum. Neurosyphilis occurs due to an invasion of the cerebrospinal fluid (CSF) by the spirochete which likely occurs soon after the initial acquisition of the disease.

What is reverse Argyll Robertson pupil?

Inverse Argyll Robertson Pupil (IARP), absence of pupillary constriction to near stimuli with retention of pupillary light reflex, has rarely been described. Chrousos and colleagues (1985) reported a child with absence of complete near reflex triad.

What is Argyll Robertson pupil?

The Argyll Robertson (AR) pupil has been defined as a pupil that is small and constricts poorly to direct light but briskly when a target within reading distance is viewed (“light-near dissociation”).

What are the causes of optic neuritis?

Infections. Bacterial infections, including Lyme disease, cat-scratch fever and syphilis, or viruses, such as measles, mumps and herpes, can cause optic neuritis. Other diseases. Diseases such as sarcoidosis, Behcet’s disease and lupus can cause recurrent optic neuritis.

What is a hippus?

What is Hippus? Rhythmic constriction and dilation of the pupil. ● Can be easily observed when light is shined on eyes. ○ Hippus is however independent of light. ● Often likened to a person dancing or a horse galloping.

Is pupillary hippus normal?

It is particularly noticeable when pupil function is tested with a light, but is independent of eye movements or changes in illumination. It is usually normal, however pathological hippus can occur.

What happens in Argyll Robertson pupil?

Argyll Robertson pupil describes the physical exam finding of bilaterally small pupils that do not constrict when exposed to bright light but do constrict when focused on a nearby object. Argyll Robertson pupil is a highly specific sign of late-stage syphilis.

Why are pupils small in Argyll Robertson?

Typically, the pupil constricts, or shrinks, in response to bright light and dilates, or expands, in response to dim light. The Argyll Robertson pupil occurs when a disease interferes with the light reflex pathway, thereby inhibiting the pupil’s natural response to bright light.

What causes black eye pupils?

Conjunctivitis (inflammation of the eye surface)

What is a relative afferent pupil defect?

Relative afferent pupillary defect (RAPD) or Marcus Gunn pupil is a medical sign observed during the swinging-flashlight test whereupon the patient’s pupils constrict less (therefore appearing to dilate) when a bright light is swung from the unaffected eye to the affected eye.

Why are the pupils of eyes black?

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.

What size are pupils?

According to the American Academy of Ophthalmology , pupils generally range in size from 2 to 8 mm. Pupil size also changes based on whether you are looking at something close or far away. When you’re focusing on an object that’s near, your pupils become smaller. When the object is far away, your pupils widen.