Abstract
Pupillary evaluation is a crucial part of every pediatric eye exam. It provides information about the structure of the eye as well as the afferent and efferent function of the eyes. It remains a quick and efficient test in the ocular evaluation. This chapter reviews the relevant neuroanatomy and the different components of the pupillary exam. The light-reflex and swinging flashlight tests are reviewed, as well as how a reverse afferent pupillary defect is detected. Clinical examples and pearls are provided to help the reader better understand the different aspects of the exam.
TopIntroduction
Pupil testing is a crucial component of every pediatric eye examination. The shape and movements of the pupils provide an enormous amount of diagnostic information. Unequal pupil size (anisocoria) or a relative afferent pupillary defect (RAPD) may indicate a serious intracranial pathology or a benign physiological condition. An RAPD may be produced by retinal disorders (including but not limited to retinal detachment, and retinal vascular disease such as central retinal artery occlusion), unilateral or asymmetric optic nerve pathology, as well as chiasmal compression and optic tract lesions due to an uneven number of optic fibers undergoing hemidecussation at the chiasm (Balcer, 2019). An RAPD will NOT be produced by refractive error, media opacities including cataracts, lesions posterior to the lateral geniculate body and non-physiologic visual loss.
Key Terms in this Chapter
Marcus Gunn Pupil: A pupil that exhibits a relative afferent pupillary defect.
Pupil: Circular opening in the center of the iris.
Amaurotic Pupil: A light without light perception, the involved pupil does not react to light (direct response), but will constrict when light is shined to the fellow normal eye (consensual response).
Neutral Density Filter Bar: An optical filter that reduces the intensity of light used to quantify the extent of a relative afferent pupillary defect.
Relative Afferent Pupillary Defect: Defect of the afferent visual pathway of one eye relative to the other eye.
Posterior Synechiae: Adhesions at the pupillary margin between the posterior iris and the anterior lens surface.
Horner Syndrome: Disruption of the sympathetic innervation of the eye, classically characterized by ipsilateral miosis, ptosis and anhidrosis (lack of sweating).
Swinging Flashlight Test: A test used to evaluate for differences in pupil reactions between the two eyes and for the presence of a relative afferent pupillary defect.
Light-Reflex Test: A test used to evaluate direct and consensual pupillary responses.