In humans the eye is of the camera type, with an iris diaphragm and variable focusing, or accommodation. It is due to damage inoptic nerve or severe retinal disease. Relative afferent pupillary defect rapd is a condition in which a persons pupils respond differently from one another to light stimuli shone, based on when it is shone into one eye at a time. An appreciation of the anatomy and understanding of the mechanisms involved in abnormal pupil responses, knowledge of the proper technique of the swinging flashlight test, and an awareness of potential pitfalls in performing this test will aid the physician in the detection of an afferent pupillary defect. We are fascinated by the material presented in the case report by forman et al. If all is normal, both pupils will remain constricted. Afferent pathway of pupillary light reflex solid yellow above. The normal pupillary light reflex is symmetric when the righteye stimulus is compared with the lefteye stimulus. Physiological anisocoria is a harmless condition that has to be distinguished from horners syndrome.
Relative afferent pupillary defect with normal visual. Moving a bright light from the unaffected eye to the affected eye would cause both eyes to dilate, because the ability to perceive the bright light is diminished. This will often result in one pupil appearing larger than the other relative afferent pupillary defect rapd. Sixtyfive participants were recruited 32 with open. Hippus is a twitchy pupil jerkiness and sometimes is normal but can be seen in response to certain drugs. Keeping an eye out for the signs and symptoms of brain tumours subconjunctival hemorrhage of the nasal conjunctiva in the left eye and relative afferent pupillary defect rapd were observed. Disorders of the parasympathetic system will impair the.
A clinical evaluation of the pupillary response reveals valuable information about the integrity of the structures involved in the pupil reflex. If a relative afferent pupillary defect is present in the opposite eye, then the pupil will constrict to light and will dilate when the light is shined in the unobserved eye. There is a useful simulation of the relative afferent pupillary defect, rapd relative afferent pupillary defect. To observe these examples, move the mouse pointer over the pupil or each eye as if it were a light pen.
To study the presence of relative afferent pupillary defect rapd in patients with glaucoma with the help of a custombuilt pupillometer. Afferent pupillary defect apd or marcusgunn pupil is a condition of the eye where the pupil doesnt dilate appropriately to the level of light reaching it. In normal circumstances, when a light is shone in one eye, both pupils constrict. This article seeks to outline the neural pathway underlying pupil constriction and provides a guide to assessing pupillary light reaction to detect a relative afferent pupillary defect.
Clinical grading of relative afferent pupillary defects. Richmond eye associates, relative afferent pupillary defect. A marcus gunn pupil indicates an afferent defect, usually at the level of the retina or optic nerve. This was likened to a case previously described by ellis. Relative afferent pupillary defect interactive clinical examples. The afferent pupillary defect is a reduction in the response of the pupils to light stimulation of an eye with impaired vision, which is detected by comparing the defective response with that. Relative afferent pupillary defect medical student education author. Relative afferent pupillary defect rapd, marcus gunn pupil an rapd is a defect in the direct response. Argyll robertson pupil one that is miotic and responds to accommodation effort, but not to light. Is the afferent or efferent pathway defective in rapd. Correlation of afferent pupillary defect with visual field. Records both the right and left pupil responses simultaneously to calculate the magnitude of the relative afferent pupillary defect in light log units pupil diameter for refractive surgery provides very accurate measurement of pupil diameter for refractive surgery screening and planning lasik and iols under. An overview how to examine pupillary function and handle pupillary abnormalities is presented. Marcus gunn pupil relative afferent pupillary defect.
With diminished afferent stimulation, less light is perceived, and pupil contraction diminishes ie, dilates as a result. Relative afferent pupillary defect medical student. An afferent defect of the pupil refers to an abnormal dilation instead of constriction when light hits the eye. The swinging flashlight test,otherwise known as the marcus gunn.
How to test for a relative afferent pupillary defect rapd. The swinging light test is used to detect a relative. Its when the eyes pupil only slightly contracts or. A doctor can identify this defect with the swinging light test, where she moves a light rapidly back and forth between. For example, if a patient with a retinal detachment in the left eye had had that pupil dilated so that the left pupil was 7 mm and the right 4 mm, and if the measured afferent pupil defect was 0. Pupillary disorders may involve the afferent pathways relative afferent pupillary defect or the efferent pathways. Relative afferent pupillary defect in eyes with retinal. We prospectively studied patients with relative afferent pupillary defects by using the swinging flashlight test. Relative affective pupillary defect affective limb. To assess the validity and reproducibility of quantitating relative afferent pupillary defects with the swinging flashlight test, using a 3second pause technique, and to compare this grading system with that using neutral density filters. Afferent pupillary defects assessment of afferent input from the retina, optic nerve, and chiasm, optic tract and midbrain till lgb damage anywhere along this portion of the visual pathway reduces the amplitude of pupil movement in response to a light stimulus the pupillary light reflex summates the entire area of the visual field, with some. Other types of eye are the simple eye, found in many invertebrates, and the compound eye, found in insects and many other click the link for more information. Start studying afferent visual system cases visual pathway cases.
Detecting a relative afferent pupillary defect using the. The pupil responses can be assessed with a virtual pen torch. Relative afferent pupillary defect rapd relative afferent pupillary defect rapd simulator. The diagram below shows the neuroanatomical pathways of the pupillary light reflex. The relative afferent pupillary defect rapd, or marcusgunn pupil is an extremely significant and highly objective clinical finding in the examination of the visual system. The pupillary light reflex regulates the amount of light reaching the retina. This article seeks to outline the neural pathway underlying pupil constriction and provides a guide to assessing pupillary light reaction to detect a relative afferent. Afferent pupillary defect synonyms, afferent pupillary defect pronunciation, afferent pupillary defect translation, english dictionary definition of afferent pupillary defect.
An afferent pupillary defect is an eye condition where one eye is less sensitive to light, and will not contract as sharply in response to light as the unaffected eye. Even in an unconscious patient, the determination of an rapd can be made. The relative afferent pupillary defect rapd, is also called the marcus gunn pupil, after the ophthalmologist that described the defect in 1883. The detection of a relative afferent pupillary defect. Marcus gunn pupil is also known as marcus gunn sign and relative afferent pupillary defect rapd. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The details of the pathway are detailed below the diagram. Rapd, relative afferent pupillary defect, marcusgunn. This pupillary sign is characterized by the presence of a normal bilateral pupillary response when the normal eye is illuminated, but when the light is quickly moved to the abnormal side there is pupillary dilatation. Optic nerve ii this is the afferent nerve it detects the light, and sends this signal to the brain.
Relative afferent pupillary defect ophthalight digital. The relative afferent pupillary defect rapd tested by shining light into the eyes and checking their pupillary response can be useful for detecting unilateral or asymmetrical disease of the. However a defect in the afferent nerve does not necessarily have to be in the optic nerve itself, it could be at the optic chiasm likely to be bilateral, or in the optic tract. This person with apd is often unaware of it except by looking in a mirror. An rapd is due to unilateral or asymmetrical disease of the retina or optic nerve. It is due to major loss of total light input in the affected eye such as massive retinal loss, optic nerve disease, etc. In this situation, the affected side is said to demonstrate an afferent pupillary defect apd, and the pupil is called a marcus gunn pupil.
However, when a light is shone in the abnormal eye of a patient with an apd, the pupil of the affected eye paradoxically dilates rather than constricts. This can be a sign of optic nerve damage, tumor, glaucoma, and a number of other eye issues. Portable pupillography of the swinging flashlight test to. The advantage to this technique is that small pupillary changes are easily seen under the slitlamp magnification. Emergency atlas of afferent pupillary defect marcus. How to test for a relative a erent pupillary defect rapd. In this case pharmacological testing with cocaine eyedrops is helpful. It is important to be able to differentiate whether a patient is complaining of decreased vision from an ocular problem such as cataract or from a defect of the optic nerve.
Also known as a marcusgunn pupil, the afferent pupillary defect is due to dysfunction of cranial nerve 2 optic nerve. In a very dark room, shine a penlight in the left eye. Find it by a swinging flashlight test a medical term. Afferent pupillary defect legal definition of afferent.
Rapd, relative afferent pupillary defect, marcusgunn pupil neuroophthalmology with dr. The sign causes much confusion, but in reality is a very simple sign. Cn2 governs sight, and is thus stimulated by light. An afferent pupillary defect is identified by examining the eyes with a bright light. A relative afferent pupillary defect apd, established by the swinging or alternating. An asymmetric pupillary light reflex or relative afferent pupillary defect rapd is a useful way to detect asymmetric retinal or optic nerve diseases. Visual pathways and pupil defects questions and study. In these cases, assume that the testing is being done in a dimly illuminated room. Correlation of afferent pupillary defect with visual field loss on automated perimetry lenworth n.