The pupillary mechanism refers to the process by which the size of the pupil in the eye is regulated. This regulation occurs through the action of the iris muscles in response to varying levels of light intensity. In bright light, the pupil constricts to reduce the amount of light entering the eye, whereas in dim light, the pupil dilates to allow more light to enter.
The IRISThe pupillary muscles located on the inner edge of the iris forms the outer boundary of the pupil. The ciliary muscles are located throughout the rest of the iris and into the ciliary body. The collarette is the region of the iris separating the pupillary muscle from the ciliary muscle. It also occupies the region where the sphincter muscle and dilator muscles overlap.
The optic nerve (cranial nerve II) carries sensory information about light intensity to the brain as part of the afferent pathway in the pupillary reflex.
While pupillary size in principle is controlled both by the sympathetic and the parasympathic nervous system, the typical closure of the pupil after illumination (i.e. the pupillary light reflex) is mediated by the parasympathetic innervation of the constrictor muscle of the pupil.
Pupillary response is controlled by the autonomic nervous system.In bright light or when looking at close objects, the parasympathetic nervous system will cause pupillary constriction by activating the sphincter pupillae muscle(s). The parasympathetic nerves that innervate the sphincter pupillae are the short ciliary nerves, which come from the ciliary ganglion in the orbit. Innervation of the ciliary ganglion is via parasympathetic pre-ganglionic fibers traveling with the occulomoter nerve from the edinger-westfall nucleus in the cranial midbrain.In low light, when looking at distant objects, or when stress levels are high (fight or flight) the sympathetic nervous system will cause pupillary dilation by activating the iris dilator muscle(s). The sympathetic nerves that innervate these muscles come from the superior cervical ganglion.
The pupillary reflex helps to regulate the amount of light entering the eye, allowing for optimal vision in changing light conditions. This reflex helps protect the retina from damage due to excessive light exposure and ensures that visual information is processed effectively by the brain.
The receptor in the pupillary reflex is the optic nerve, which senses changes in light intensity. The effector is the circular and radial muscles of the iris, which control the size of the pupil. In the pupillary reflex, both the receptor and the effector work together to adjust the size of the pupil to regulate the amount of light entering the eye.
pupillary light reflex is controlled by parasympathetic branch of Autonomous nervous system
Persistent pupillary membrane is a condition where parts of a fetal membrane stay attatched to the eye after birth. It can cause cataracts.
Pilocarpine is a cholinergic agonist that stimulates muscarinic receptors in the eye, leading to miosis (pupillary constriction) and increased aqueous humor outflow, lowering intraocular pressure. This mechanism of action is beneficial in treating conditions like glaucoma.
The IRISThe pupillary muscles located on the inner edge of the iris forms the outer boundary of the pupil. The ciliary muscles are located throughout the rest of the iris and into the ciliary body. The collarette is the region of the iris separating the pupillary muscle from the ciliary muscle. It also occupies the region where the sphincter muscle and dilator muscles overlap.
Yes, the pupillary light reflex is mediated by both autonomic and somatic nervous systems. The autonomic nervous system controls the constriction of the pupil in response to light, while the somatic nervous system controls the movement of the muscles that dilate and constrict the pupil.
The optic nerve (cranial nerve II) carries sensory information about light intensity to the brain as part of the afferent pathway in the pupillary reflex.
While pupillary size in principle is controlled both by the sympathetic and the parasympathic nervous system, the typical closure of the pupil after illumination (i.e. the pupillary light reflex) is mediated by the parasympathetic innervation of the constrictor muscle of the pupil.
Pupillary response is controlled by the autonomic nervous system.In bright light or when looking at close objects, the parasympathetic nervous system will cause pupillary constriction by activating the sphincter pupillae muscle(s). The parasympathetic nerves that innervate the sphincter pupillae are the short ciliary nerves, which come from the ciliary ganglion in the orbit. Innervation of the ciliary ganglion is via parasympathetic pre-ganglionic fibers traveling with the occulomoter nerve from the edinger-westfall nucleus in the cranial midbrain.In low light, when looking at distant objects, or when stress levels are high (fight or flight) the sympathetic nervous system will cause pupillary dilation by activating the iris dilator muscle(s). The sympathetic nerves that innervate these muscles come from the superior cervical ganglion.
In the experiment on the photopupillary reflex, when light is shone into one eye causing pupillary constriction (direct response), the nonilluminated eye will also exhibit pupillary constriction (consensual response) due to neural connections between both eyes and the brain. This demonstrates the consensual response component of the pupillary light reflex.
The diagnostic exam should include measurement of visual acuity under both low and high illumination, biomicroscopy with pupillary dilation, stereoscopic fundus examination with pupillary dilation.
The average pupillary distance for women is 62mm and men 64mm