Eye Anatomy and Physiology

The branch of medicine that deals with the eye, its diseases, and its related structures.

The structure and parts of the eye.

How the eye functions, including processes like focusing and light reception.

A thorough evaluation of the eye's structure and function to diagnose potential issues.

Conditions impacting the eye's ability to focus light correctly, leading to blurry vision.

A group of eye conditions causing progressive loss of vision due to damage to the optic nerve.

Conditions affecting the eyelids, including infections and inflammations.

Treatment methods used for conditions of the eye, including medications, and surgery

The optic groove forms during the 3rd week of development, marking a key step in eye formation.

The lens vesicle develops from the lens plate during the 1st month of gestation.

The hyaloid vessels form during the 1st month of gestation, and they play a supporting role in the development of the embryo.

The embryonic fissure closes by the 1 ½ months after conception to complete the eye cavity.

The retinal pigment epithelium differentiates during the first months after conception.

Corneal and trabecular endothelium form in the 7th week of gestation during the first wave of eye development.

The retinal vasculature (blood vessels in the retina) begins to form in the 4th month of development.

Differentiation of precursors of rods and cones occurs in the third month of development.

The optic vesicle grows outwards, meets ectoderm, and invaginates to become the optic cup, with a temporary open fissure.

The inner layer of the optic cup forms the retina, which is where nerve fibers grow towards the brain.

The outer layer of the optic cup, remaining as a single layer providing pigment.

The temporary opening in the optic cup, allowing for the hyaloid artery to pass.

Surface ectoderm thickens to form lens plate, invaginates to lens vesicle, then separates into lens.

Temporary artery that nourishes the developing eye structures before disappearing.

The hyaloid artery's role is eventually replaced by vitreous jelly, secreted nearby.

The eye wall consists of the dense, tough sclera (most of it) and the transparent cornea (front part).

A single layer of cells covering the iris's anterior surface, except in minute depressions.

The sensory nerves in the iris originate from the trigeminal nerve.

Pupil constriction is controlled by parasympathetic nerves from the oculomotor nerve.

Pupil dilation is controlled by sympathetic nerves from the cervical sympathetic chain.

The ciliary body is roughly triangular in shape, with the base facing forward.

The ciliary muscle originates from the ciliary tendon.

The ciliary muscle has meridional, oblique, and iridic fibers.

The inner surface of the ciliary body, the pars plicata has folds (ciliary processes), while the pars plana is smooth.

A single layer of cells between photoreceptors and Bruch's membrane; crucial for retinal metabolism and light absorption.

Transporting nutrients to photoreceptors, removing waste products, and absorbing excess light.

Dark pigment in RPE cells that absorb excess light.

RPE cell organelles containing discarded rod discs.

Light-sensitive cells in the retina, the end-organs of vision.

Rods continuously replace damaged discs.

Outer segment (light reception), inner segment (maintenance), nuclear region and synaptic layer.

Discarded discs are engulfed by RPE cells.

The size of the pupil is regulated by the afferent and efferent pathways of the pupillary light reflexes, as well as the function of the sphincter and dilator pupillae muscles.

Pupil dilation with normal mobility can occur in myopia (nearsightedness) and situations where muscle tone is compromised or the nervous system is excited.

Pupils tend to be smaller in infants and older adults.

Very large, nonreactive pupils suggest that a mydriatic (pupil-dilating substance) has been used, often accidentally, such as when an ointment containing atropine is rubbed on the eye.

Immobile pupils, often accompanied by dimness of vision, especially for close-up work, is a common symptom related to a mydriatic (pupil-dilating) substance accidentally applied to the eye.

Pupils are large and immobile in cases of bilateral blindness, suggesting a loss of retinal and optic nerve function. This is distinct from pupilloplegia (bilateral efferent pupillary defect).

Bilateral blindness can be distinguished from pupilloplegia by testing the near reflex. Even though the patient cannot see their thumb held close to their face, they can still attempt to accommodate, causing pupillary constriction.

Dilated and immobile pupils can result from third nerve palsies (absolute paralysis of the pupil), often accompanied by paralysis of accommodation, leading to internal ophthalmoplegia.