Ocular Anatomy and Embryology in Pediatric Optometry (2)

Eyelid

The fold of skin that covers and protects the eye, playing a crucial role in maintaining moisture and shielding the eye from debris.

Ciliary Body

A structure in the eye that produces aqueous humor and contains the muscles that control the shape of the lens for focusing.

Lens

A transparent structure in the eye that refracts light to help focus images on the retina.

Choroid

The vascular layer of the eye between the retina and the sclera, providing nourishment to the outer layers of the retina.

Retina

The light-sensitive layer at the back of the eye that converts light into neural signals for vision.

Sclera

The white outer coating of the eyeball, providing structural support and protection.

Cornea

The transparent front part of the eye that covers the iris and pupil, playing a key role in focusing light.

Iris

The colored part of the eye that controls the size of the pupil and the amount of light entering the eye.

Pupil

The opening in the center of the iris that regulates the amount of light that enters the eye.

Ectoderm

The outermost germ layer that contributes to the formation of the nervous system and skin.

Mesoderm

The middle germ layer that develops into connective tissues, muscles, and the vascular system.

Endoderm

The innermost germ layer that forms the lining of the digestive and respiratory systems.

Optic Pits

Indentations in the forebrain that give rise to the optic vesicles during embryonic development.

Optic Vesicles

Sac-shaped extensions of the optic pits that develop into structures of the eye.

Neural Plate

A thickened region of ectoderm that forms the neural tube and gives rise to the central nervous system.

Neural Folds

The raised edges of the neural plate that eventually fuse to form the neural tube.

Neural Tube

The embryonic structure that develops into the central nervous system, including the brain and spinal cord.

Mesenchyme

Loose connective tissue that develops into various structures, including those of the eye and orbit.

Neural Crest

Cells that separate from the neural folds and contribute to the formation of various structures, including parts of the eye.

Neural Ectoderm

The tissue that forms the neural tube and contributes to the development of the nervous system.

Surface Ectoderm

The outer layer of cells that contributes to the formation of the lens and other structures in the eye.

Optic Stalk

The narrow connection between the optic vesicle and the neural tube that forms during eye development.

Lens Vesicle

A hollow sphere formed during eye development that separates from the surface ectoderm and is composed of two layers of cells.

Optic Cup

A structure formed from the invagination of the optic vesicle, consisting of inner and outer layers that will develop into various parts of the eye.

Retinal Pigment Epithelium (RPE)

The outer layer of the optic cup that differentiates first and is responsible for absorbing excess light and supporting photoreceptors.

Neural Retina

The inner layer of the optic cup that develops into the light-sensitive layer of the eye containing photoreceptors.

Optic Fissure

A cleft formed during the development of the optic cup, where mesenchyme enters and contributes to the formation of various eye structures.

Hyaloid Vasculature

A network of blood vessels that supplies nutrients to the developing lens and retina during embryonic development.

Anterior Iris Epithelium

The layer of cells that develops from the outer layer of the optic cup and forms part of the iris.

Cell Elongation

The process by which cells in the lens vesicle stretch and grow to form lens fibers during eye development.

Secondary Lens Fibers

Cells that elongate and surround the embryonic nucleus of the lens, contributing to its growth and shape.

Embryonic Nucleus

The central part of the lens formed by primary lens fibers during early eye development.

Basal Lamina

A thin layer of extracellular matrix that supports the cells of the optic cup and will become the lens capsule.

Mitosis

The process of cell division that occurs in the anterior epithelial cells of the lens, contributing to the formation of new lens fibers.

Vascular Endothelium

The inner lining of blood vessels that develops from mesodermal mesenchyme during eye formation.

Retinal Vasculature Development

The process by which blood vessels form in the retina, crucial for supplying nutrients and oxygen.

Marginal Zone

An anuclear region that serves as a precursor to the internal limiting membrane, separating the marginal zone from the vitreal cavity.

Transient Fiber Layer of Chievitz

A temporary layer in the developing retina characterized by a nucleus-free area between the inner and outer neuroblastic layers.

Neuroblastic Layers

Two layers formed during retinal development, where differentiation of neural retinal cells occurs.

Ganglion Cells

Neurons in the retina that transmit visual information from photoreceptors to the brain.

Amacrine Cells

Interneurons in the retina that play a role in processing visual signals.

Müller Cells

Supportive glial cells in the retina that maintain homeostasis and provide structural support.

Apoptosis

A programmed cell death process essential for sculpting retinal circuitry and eliminating excess cells.

Photoreceptor Cells

Cells in the retina that detect light and convert it into electrical signals.

Foveal Development

The process involving the displacement of inner retinal components, migration of photoreceptors, and maturation of photoreceptors to form the fovea.

Cone Differentiation

The process by which cone photoreceptors develop and mature, contributing to color vision.

External Limiting Membrane

A structure formed by adhering junctions between photoreceptor cells, crucial for retinal integrity.

Bipolar Cells

Neurons in the retina that transmit signals from photoreceptors to ganglion cells.

Horizontal Cells

Retinal interneurons that integrate and regulate input from multiple photoreceptor cells.

Retinal Cell Migration

The movement of various retinal cells to their designated locations during development.

Macular Area

The central region of the retina responsible for high-acuity vision, where a dense accumulation of nuclei occurs.

Inner Nuclear Layer

A layer in the retina containing the cell bodies of bipolar cells, amacrine cells, and horizontal cells.

Rod Cells

Photoreceptors responsible for vision in low light conditions.

Retinal Ganglion Cell (RGC) Apoptosis

The process of programmed cell death in retinal ganglion cells, essential for refining the retinal circuitry.

Retinal Layers

The distinct layers of cells in the neural retina, including the ganglion cell layer, inner nuclear layer, and outer nuclear layer.

Marginal Layer

A layer in the developing retina where ganglion cells are displaced, allowing cones to be the only neural cell bodies in the center.

Cones

Photoreceptor cells in the retina responsible for color vision and sharp visual acuity.

Retinal Vessels

Blood vessels that emerge from the hyaloid artery and supply the developing retina.

Corneal Epithelium

The outermost layer of the cornea formed from epithelial cells that align during development.

Foveola

The central region of the retina with the highest density of cones, responsible for sharpest vision.

Bowman's Layer

An acellular layer of the cornea formed by fibroblasts and epithelial secretions.

Choriocapillaris

A layer of capillaries in the choroid that provides nutrients to the outer retina.

Vitreous Humor*

A gel-like substance filling the eye's vitreous space, providing support to the retina.

Pupillary Membrane

A transient membrane that forms between the lens and cornea during development.

Anterior Chamber

The fluid-filled space between the cornea and the iris, lined by endothelium.

Aqueous Humor

The clear fluid produced by the ciliary body that fills the anterior chamber and maintains intraocular pressure.

Secondary Vitreous

The gel-like substance produced by the neural retina and hyalocytes that encloses the primary vitreous.

Tertiary Vitreous

A structure formed by the accumulation of mesenchymal cells in the anterior chamber.

Henle's Fiber Layer

A layer in the retina formed by the inner fibers of cones that elongate and adopt an oblique orientation.

Central Retinal Artery

The main blood vessel supplying the retina, derived from the hyaloid artery.

Descement's Membrane

The basement membrane of the corneal endothelium, which provides structural support.

Trabecular meshwork

A structure in the eye that becomes visible as a triangular mass of cells by the 4th month of development, contributing to aqueous humor drainage.

Intratrabecular spaces

Spaces formed within the trabecular meshwork, likely resulting from programmed cell death.

Tight junctions

Cellular structures that become evident in the endothelial lining of the canal by the 4th month, helping to maintain the integrity of the barrier.

Optic nerve

A structure that develops from the optic stalk and is responsible for transmitting visual information from the retina to the brain.

Neuroglial sheath

The outer layer of the optic stalk that becomes the protective covering surrounding the optic nerve.

Tarsal plates

Structures that are among the first to develop in the eyelids, providing support and shape.

Meibomian glands

Glands that develop from buds at the margins of eyelid folds, responsible for secreting oil to prevent tear evaporation.

Orbital fat

Connective tissue derived from neural crest cells that provides cushioning for the eye within the orbit.

Extraocular muscles

Muscles responsible for eye movement, derived from mesoderm, with connective tissue components originating from neural crest.

Hypermetropic

A condition commonly seen in newborns where distant objects are seen more clearly than near ones, typically measured at +2 diopters.

Nasolacrimal system

A drainage system for tears that develops from a cord of surface ectodermal cells.

Lacrimal gland

A gland that continues to develop after birth, responsible for tear production.

Myelination

The process of forming a myelin sheath around the axons of the optic nerve, which begins once the fibers reach the lateral geniculate nucleus.

Desmosomes

Cell structures that join the margins of the fused eyelids, breaking down to allow eyelid separation.

Ciliary muscle

A muscle involved in the accommodation of the lens, derived from mesoderm.

Uveal pigment cells

Cells that contribute to the pigmentation of the uveal tract in the eye, originating from mesoderm.

Optic Nerve Fibres

Nerve fibers that transmit visual information from the retina to the brain.

Lamina Cribrosa

A sieve-like structure in the optic nerve head that supports the optic nerve fibers.

Macula

A small area in the retina responsible for sharp central vision, which fully develops several months after birth.

Vitreous Humor

A gel-like substance that fills the space between the lens and the retina, providing shape and support to the eye.

Bruch's Membrane

The innermost layer of the choroid that separates the choroidal blood supply from the retinal pigment epithelium.

Conjunctiva

A thin membrane that covers the front of the eye and lines the eyelids, providing lubrication.

Meibomian Gland

Glands located in the eyelids that secrete oils to prevent evaporation of the tear film.

Photoreceptors

Cells in the retina that detect light and convert it into electrical signals for vision.

Rods

Photoreceptor cells in the retina that are responsible for vision in low light conditions.

Corneal Diameter

The measurement across the cornea, which reaches adult size by approximately two years of age.

Zonular Fibers

Fibers that connect the ciliary body to the lens, helping to hold the lens in place.

Embryonic and Fetal period

The critical time for eye formation, where any damage can lead to congenital eye defects.

Hypermetropia

A condition where distant objects are seen more clearly than near ones, typically measured at +2 to +3 diopters in infants.