What is a Marcus Gunn pupil?
What is a 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.
How do you test Marcus Gunn’s pupil?
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.
How do you use relative afferent pupillary defect?
- Figure 2. Open in a separate window. Swinging-light test – normal (no RAPD) Illumination of either eye induces normal and equal pupil responses in both eyes (consensual responses).
- Figure 3. Open in a separate window.
- Figure 4. Open in a separate window.
How do you check your pupils for APD?
Most commonly, the presence of an APD is evaluated in office using the swinging flashlight test, in which each pupil is illuminated and the velocity and amplitude of the pupillary response is compared. In a healthy patient, light stimulation into one pupil results in equal constriction of both.
What causes Marcus Gunn?
The exact cause of Marcus Gunn phenomenon is not known. For reasons that are unclear, there is a bad connection between the nerves that stimulate, and the muscles that move, the eyelids and the jaw. Some clinical researchers believe that about half of the cases of Marcus Gunn phenomenon are genetically determined.
Can Marcus Gunn be cured?
Treatment is only necessary if there is an eye or vision problem, although some people choose to have the condition corrected for cosmetic reasons. Treatment for Marcus Gunn syndrome usually corrects the condition with no long-term problems.
What causes an afferent pupillary defect?
Afferent pupillary defects are caused by lesions in the ‘front end’ of the pupillary light reflex pathway and most commonly by lesions in the retina and optic nerve.
What causes 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.
Can Marcus Gunn syndrome be cured?
Treatment of Marcus Gunn phenomenon is usually not needed because the condition tends to grow less noticeable with age. Genetic counseling may be of benefit for patients and their families. Other related eye problems such as strabismus, amblyopia, etc., may be corrected with eyeglasses, surgery and/or drugs.
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.