What does APD stand for in medical terms?
Afferent Pupillary Defect (“APD”) Also known as a “Marcus-Gunn Pupil,” the Afferent Pupillary Defect is due to dysfunction of Cranial Nerve 2 (Optic Nerve).
Is APD the same as glaucoma?
APD and Glaucoma. Determining the presence or absence of an APD is of great clinical value, particularly in guiding the practitioner in the course of treatment for their glaucoma patients. Though glaucoma is typically a bilateral condition, it often initially presents unilaterally or bilaterally with variation in severity between the two eyes.
What is the pathophysiology of right APD?
Patient has a Right APD. Pathology: CN-2 carries the impulse to the brain (occipital lobe). But en route, it synapses to the Edinger-Westphal nucleus in mid-brain. There, CN-3 (Oculomotor Nerve) travels back to constrict the pupil (direct response), and also to the contralateral pupil (consensual response).
What are the disadvantages of the APD test?
One disadvantage is that a small but detectable APD is sometimes observed in healthy subjects, limiting the specificity of this test modality. 6
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What is the difference between RAPD and APD?
RAPD vs APD In literature, and clinical practice, RAPD, and APD, or afferent pupillary defect, may be used synonymously. However, RAPD is technically describing the relative response of one pupil so there is no such thing as bilateral RAPD and, for a RAPD to exist, the damage must be asymmetric between the eyes.
How do they test for APD eyes?
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 happens in relative afferent pupillary defect?
Relative Afferent Pupillary Defect (RAPD) is a condition in which pupils respond differently to light stimuli shone in one eye at a time due to unilateral or asymmetrical disease of the retina or optic nerve (only optic nerve disease occurs in front of the lateral geniculate body).
Can a cataract cause an APD?
A: “It is important to understand that a cataract, no matter how asymmetric in presentation, will never cause a relative afferent pupillary defect in that eye,” says Kelly Herron, OD, of Omni Eye Services in Atlanta.
What does APD stand for?
Auditory processing disorder (APD) is a hearing problem that affects about 3%–5% of school-aged children. Kids with this condition, also known as central auditory processing disorder (CAPD), can't understand what they hear in the same way other kids do. This is because their ears and brain don't fully coordinate.
How do you calculate APD?
Testing. Your doctor can use a hearing test to see if your child's issues are caused by hearing loss, but only a hearing specialist, called an audiologist, can diagnose APD. The audiologist will do a series of advanced listening tests in which your child will listen to different sounds and respond when they hear them.
How do you know if APD is reversed?
Reverse RAPD, or reverse testing for RAPD, utilizes the swinging flashlight test while evaluating the normal, unaffected pupil for dilation. This finding is present in every RAPD but most examiners are used to only observing the affected pupil during the swinging flashlight test.
What part of the brain controls pupil dilation?
hypothalamusThe pupillary dilation pathway is a sympathetically driven response beginning in the hypothalamus and ending with the contraction of the dilator pupillae muscle.
What cranial nerve is responsible for afferent pupillary reflex?
The optic nerveThe optic nerve, or more precisely, the photosensitive ganglion cells through the retinohypothalamic tract, is responsible for the afferent limb of the pupillary reflex; it senses the incoming light.
Can a dense cataract cause and APD?
Thus, a dense cataract causes an RAPD in the contralateral eye by increasing the pupillomotor effectiveness of the stimulus light and that this is the reason why even a brunescent cataract does not cause an RAPD in the same eye.
What is pupillary defect?
pupillary defect, efferent. A defect of the pupillary reflex caused by a lesion along the pathway of either the parasympathetic supply from the Edinger–Westphal nucleus to the sphincter pupilla e muscle of the iris (Adie's pupil) or the ocular sympathetic supply from the ciliospinal centre to the dilator pupillae muscle of the iris ...
How to tell if you have an afferent pupillary defect?
An afferent pupillary defect may be subtle; when only one eye is affected the examiner can help to confirm its presence in two ways: 1. Look for a relative a fferent pupillary defect using the swinging light test, which accentuates the difference between the direct light reflex of each eye.
What is the optic disc?
Venous pulsations: the optic disc is an accessible manometer reflecting CSF pressure. In 80% of normal patients the retinal veins are subtly pulsatile as they cross the disc. These pulsations cease if the intracranial pressure rises. When no pulsations are observed, these should be induced by the slightest digital pressure exerted on the globe. This is feasible in sleepy infants or cooperative children aged 3 years and above. It is best to warn the child that you intend to press gently on their eye through the eyelid as you examine them with the ophthalmoscope. To reduce their apprehension, show them what you will do, then repeat while observing the disc through the ophthalmoscope. If significant pressure is necessary to induce venous pulsations, or these can only be induced at the same time as the artery begins to pulsate, the intracranial pressure is abnormally high.
What does decreased direct light reflex mean?
Pupils: if the parasympathetic pathway for pupillary constriction is normal (efferent pathway), a decreased direct light reflex indicates anterior visual pathway (afferent pathway) disease.
What is a slowed pupil response?
In other words a slowed or absent pupil response points to a disorder of the retina, optic nerve, chiasm, or anterior optic tract. Conversely, posterior visual pathway disease is associated with normal pupil reactions.
Can retinal disease cause a pupillary defect?
Severe retinal disease may cause a relative afferent pupillary defect, although the retinal disease must be markedly asymmetric to produce the finding and, once the finding appears, it is subtle compared with that seen in optic nerve disease.14.
Who discovered the relative afferent pupillary defect?
Although the relative afferent pupillary defect was described by R. Marcus Gunn in 1904, it is clear from his report that the sign was generally known to clinicians of his time.
What is pupillary response?
The testing of the pupillary response to light is routinely performed by the eye care practitioner and imparts valuable information regarding the presence, laterality or magnitude of diseases that mainly affect the optic nerve, such as glaucoma. 1 A relative afferent pupillary defect (APD), when present, is an important marker in the evaluation of unilateral or asymmetric function of the anterior visual pathway. 1-4 It serves as an indication of reduced afferent input from the retina or optic nerve when compared with the fellow eye. 3
Can cataracts cause APD?
Though it is rare for a cataract to cause an APD, one study reported that in severe, unilateral cases when vision is counting fingers or worse, an APD is often observed but, in the better-seeing eye, that later disappeared following extraction.
What is a RAPD test?
Relative Afferent Pupillary Defect (RAPD) is a condition in which pupils respond differently to light stimuli shone in one eye at a time due to unilateral or asymmetrical disease of the retina or optic nerve (only optic nerve disease occurs in front of the lateral geniculate body). Swinging flashlight test or Marcus Gunn test is one of the most basic eye exams that neurologists, ophthalmologists, optometrists and other physicians perform when visiting most of their patients. The doctor will ask the patient to look ahead then shines a penlight first toward one eye, then swing to the other, alternating quickly to observe patient’s pupils’ response to the light. In case if both pupils do not show a similar response to the light stimuli, shone in one eye at a time, the patient will be diagnosed with RAPD or Marcus Gunn pupils. off note if the condition is bilateral and symmetrical, there will not be a RAPD but bilateral APD. The results of this simple yet very important test help doctors in early diagnosis of many important eye related diseases such as optic neuropathy and multiple sclerosis .
Does pupil constriction change?
Normally, the pupil constriction does not change as the light is swung from eye to eye. When the light is moved quickly from eye to eye, both pupils should hold their degree of constriction. But even under the best condition, it is hard to perform this manual test accurately.
Can RAPD cause APD?
Glaucoma: While glaucoma normally is a bilateral disease, if one optic nerve has particularly severe damage, an RAPD can be seen however it can cause bilateral APD.
Can RAPD be seen with macular degeneration?
Retinal detachment: A RAPD can often be seen if the macula is detached, or if at least two quadrants of retina are detached. Severe macular degeneration: If unilateral and severe, a RAPD can be seen. Usually the visual acuity would be less than 20/400.
Can RAPD be seen in the eye?
Thus, in a patient with a homonymous hemianopia from an optic tract disorder, an RAPD could be seen in the eye with the temporal visual field defect. The nasal retina serves the temporal visual field, and these are the fibers that would cross at the chiasm .
Extraocular muscles
Hirschberg Have the patient look at a light shining from directly in front. In a non-strabismic patient, the corneal light reflex should be close to the center of the pupil. If the light reflex is deviated, you can estimate the degrees of deviation using the table below.
Disease Severity Staging
Cataract Grading: Thylefors B, Chylack LT, Konyama K et al. A simplified cataract grading system. Ophthalmic Epidemiology 2002. http://www.ncbi.nlm.nih.gov/pubmed/11821974
Exam Findings
Scheie Gonioscopy: Scheie HG. Width and pigmentation of the angle of the anterior chamber; a system of grading by gonioscopy. AMA Arch Ophthalmology 1957. http://www.ncbi.nlm.nih.gov/pubmed/13457548
