![]() ![]() Have an increasing effect with larger pupils. Their experiments of optical line-spread function, CampbellĪnd Gubisch 7 found the optimal pupil diameter to be 2.4 mm scatter and focusing defects Outweighs any benefit of miosis-induced increase in focal depth. Pupillary size decreases, light diffraction at the pupil edge becomesĪ more significant factor in reducing image quality this generally to increase depth of field (analogous to the f-stop settingĪs pupillary size increases, so does chromatic and spherical aberration.Imperfections of the optical system of the cornea and lens and to diminish the chromatic and spherical aberrations produced by the peripheral.to regulate the amount of light reaching the retina.The pupil may be considered to have three major optic functions: In: Thompson HS, Daroff RB, Frisen L, et al (eds): Topics (Reprinted with permission from Loewenfeld IE: Pupillary changes related In contrast, reflexesĮlicited by short flashes show relatively flat age curve. Note early peak, followedīy decline with age for reactions to long light flashes. Indicate the number of subjects per age group. ShadedĪrea ( left bracket) is normal range for 3-second flashes stippled area is normal 3 Normal ranges of light reflex amplitude for long and for short flashes. In: Thompson HS, Daroff RB, Frisen L, et al (eds): (Reprinted with permission from Loewenfeld IE: Pupillary changes Note the wide scatter but obvious age trend. Shows horizontal diameters in millimeters, ordinate shows subjects'Īge in years. 2 Pupillary size in darkness of 1263 subjectsĬhosen at random average pupil size was used (/2). Nucleus has been implicated as the mechanism for age-relatedĭiminished pupil size in dim illumination. Decreased central sympathetic inhibition to the Edinger-Westphal Of amplitude of the light reflex declines with increasing age ( Fig. Pupillary reactivity, at least to “long” (3-second) lightįlashes, also seems related to age the range 5, 6 The pupil of the neonate is miotic but increases in size during the firstĭecade of life from the second decade on, the pupil steadily becomes To schizophrenia and from cataracts to hemorrhoids. This incessant change in pupil size has no pathologic significance, 4 although it is described in diverse conditions ranging from encephalitis In the awake state, the pupil is rather constantly moving, a condition Brain stem diagram represents section through levelĪt a given moment, any or all of the aforementioned factors may variably That uniocular light stimulus evokes bilateral and symmetric pupillaryĬonstriction. Postganglionic fibers innervate the pupillary sphincter muscles. After synapsing in the ciliary ganglia (CG), the 3 Preganglionic parasympathetic fibers ( heavy dashed lines) leave ventral aspect of midbrain in the substance of the third cranial Neurons to both Edinger–Westphal parasympathetic motor nuclei (E–W), which comprise the dorsal aspect of the oculomotor The PTN is connected by crossed and uncrossed intercalated Geniculate nucleus (LGN) is bypassed by these pupillomotorįibers. Terminate in pretectal nuclear complex (PTN). Light in left eye ( dotted arrow) stimulates retina (RET), whose afferent axons ( fine dashed lines) ascend optic nerve (ON), decussate at chiasm (CHI), and Iris color, on the other hand, may affectĬonstriction amplitude and velocity but not pupillary size. Occipital cortex above the pretectal area and from the reticular formation Light adaptation, and supranuclear influences from the frontal and Retinal illumination, the near-effort reflex, the state of retinal 2 In addition, the size of the pupils is influenced by the intensity of Pupillary size directly by dilator muscle innervation or indirectlyīy central inhibition of the oculomotor parasympathetics (Edinger-Westphal Outflow to the pupillary sphincter and ciliary muscle and (6) theĮfferent sympathetic pathway from the hypothalamus In the oculomotor nuclear complex (5) the efferent parasympathetic Of the superior colliculus (4) pretectal area of the mesencephalonĪnd the interconnecting neurons to pupilloconstrictor motor cells Not the lateral geniculate body) (3) brachium These include: (1) retinal receptors (2) ganglionĬell axons in the optic nerve, optic chiasm, and optic tract (but Pupillary function depends on the integrity of the structures along theĬourse of the pupillomotor pathway ( Fig. Loewenfeld's scholarly text, The Pupil: Anatomy, Physiology and Clinical Applications, is recommended reading for encyclopedic information about the pupil. They may be sampled and evaluated by simple clinical procedures. That control pupil size and reactivity are highly complex, yet The retina, the special sensory apparatus that it serves. The pupil is a kinetic indicator of both ocular motor function and the Protecting them like the pupil* of His eye. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |