This document provides an overview of ocular embryology, including the development of ocular structures from conception through birth. Key milestones include the formation of the optic vesicle and cup, lens vesicle, and closure of the embryonic fissure during the 4th-8th weeks of gestation. After birth, structures like the lacrimal system mature, intraocular pressure increases gradually to adult levels, and the iris continues developing pigmentation.
The development of the eye begins at day 22 of gestation. The optic vesicle forms from the neuroectoderm and gives rise to the retina, iris, and optic nerve. The lens forms from surface ectoderm. Mesoderm surrounding the optic vesicle forms fibrous and vascular coats. Neural crest cells contribute to the choroid, sclera, and corneal epithelium. By the 5th month, all retinal layers are recognizable. The lens, vitreous, blood vessels, eyelids, and lacrimal apparatus also develop from specified tissues during gestation. By birth, the structures of the eye are largely complete.
Eye development begins at 3 weeks in the embryo and continues through 10 weeks. Cells from both mesodermal and ectodermal tissues contribute to eye formation, with the eye derived from neuroepithelium surface ectoderm and extracellular mesenchyme. The major eye structures including the retina, lens, cornea, iris, ciliary body, choroid, and optic nerve are developed from the optic vesicle, lens placode, and surrounding mesenchyme between 3-10 weeks of gestation.
The document summarizes the embryology of the eye. It describes how the eye develops from four primordia originating from different germ layers by the third week of gestation. Key structures like the lens, cornea, iris and anterior chamber develop through the fourth week. The optic cup forms by the fourth week and most basic eye structures are present by the seventh week. Factors regulating eye development include growth factors, homeobox genes and neural crest cells. Common congenital anomalies that can occur due to disturbances during embryogenesis are also discussed.
The document summarizes the development of the eye from early embryogenesis through birth. It discusses the formation of the three primary germ layers - ectoderm, mesoderm, and endoderm - and how they give rise to the different tissues of the eye. Key stages of eye development are described from 3-5 months of gestation. The retina, lens, vitreous humor, choroid, sclera and other ocular structures develop from specific germ layers and their precursor tissues like the neural crest.
1. During the 5th week of development, the optic cup begins to invaginate from the optic vesicles and forms the double-walled optic cup with inner and outer layers. The lens placode also begins to form from surface ectoderm.
2. By the 7th week, the choroid fissure has closed and the optic cup forms the round opening of the future pupil. The lens placode has invaginated to form the lens vesicle.
3. Various structures develop from the layers of the optic cup, including the neural retina from the inner layer and the pigmented retina and iris from the outer layer. The iris muscles and ciliary body also begin to form at this stage
Embryology of the eye by Sumayya Naseem OptometristSumayya Naseem
The human eye begins developing in the embryo as shallow grooves on the sides of the forebrain that form optic vesicles. These vesicles invaginate to form the double-walled optic cup, with the inner layer forming the retina and the outer layer forming the pigmented choroid layer. The surface ectoderm then invaginates to form the lens vesicle. By the fifth week, the optic cup tissues differentiate into the inner retinal layer and outer choroid layer. The optic stalk transforms into the optic nerve. Visual reflexes like the pupillary light reflex develop by 30 weeks gestation. Abnormalities can occur if development of structures like the choroid fissure or iridopupillary membrane is disrupted.
This document discusses the embryology of the eye. It notes that the eye develops from the ectoderm and mesoderm germ layers. The eye begins as optic vesicles that invaginate to form the two-layered optic cup. The inner layer forms the retina and outer forms the retinal pigment epithelium. Growth factors, homeobox genes, and neural crest cells regulate eye development. The optic cup, lens, vitreous body, iris, ciliary body, retina and other structures continue developing throughout gestation. Failure of structures to form properly can result in various congenital eye anomalies.
The development of the eye begins at day 22 of gestation. The optic vesicle forms from the neuroectoderm and gives rise to the retina, iris, and optic nerve. The lens forms from surface ectoderm. Mesoderm surrounding the optic vesicle forms fibrous and vascular coats. Neural crest cells contribute to the choroid, sclera, and corneal epithelium. By the 5th month, all retinal layers are recognizable. The lens, vitreous, blood vessels, eyelids, and lacrimal apparatus also develop from specified tissues during gestation. By birth, the structures of the eye are largely complete.
Eye development begins at 3 weeks in the embryo and continues through 10 weeks. Cells from both mesodermal and ectodermal tissues contribute to eye formation, with the eye derived from neuroepithelium surface ectoderm and extracellular mesenchyme. The major eye structures including the retina, lens, cornea, iris, ciliary body, choroid, and optic nerve are developed from the optic vesicle, lens placode, and surrounding mesenchyme between 3-10 weeks of gestation.
The document summarizes the embryology of the eye. It describes how the eye develops from four primordia originating from different germ layers by the third week of gestation. Key structures like the lens, cornea, iris and anterior chamber develop through the fourth week. The optic cup forms by the fourth week and most basic eye structures are present by the seventh week. Factors regulating eye development include growth factors, homeobox genes and neural crest cells. Common congenital anomalies that can occur due to disturbances during embryogenesis are also discussed.
The document summarizes the development of the eye from early embryogenesis through birth. It discusses the formation of the three primary germ layers - ectoderm, mesoderm, and endoderm - and how they give rise to the different tissues of the eye. Key stages of eye development are described from 3-5 months of gestation. The retina, lens, vitreous humor, choroid, sclera and other ocular structures develop from specific germ layers and their precursor tissues like the neural crest.
1. During the 5th week of development, the optic cup begins to invaginate from the optic vesicles and forms the double-walled optic cup with inner and outer layers. The lens placode also begins to form from surface ectoderm.
2. By the 7th week, the choroid fissure has closed and the optic cup forms the round opening of the future pupil. The lens placode has invaginated to form the lens vesicle.
3. Various structures develop from the layers of the optic cup, including the neural retina from the inner layer and the pigmented retina and iris from the outer layer. The iris muscles and ciliary body also begin to form at this stage
Embryology of the eye by Sumayya Naseem OptometristSumayya Naseem
The human eye begins developing in the embryo as shallow grooves on the sides of the forebrain that form optic vesicles. These vesicles invaginate to form the double-walled optic cup, with the inner layer forming the retina and the outer layer forming the pigmented choroid layer. The surface ectoderm then invaginates to form the lens vesicle. By the fifth week, the optic cup tissues differentiate into the inner retinal layer and outer choroid layer. The optic stalk transforms into the optic nerve. Visual reflexes like the pupillary light reflex develop by 30 weeks gestation. Abnormalities can occur if development of structures like the choroid fissure or iridopupillary membrane is disrupted.
This document discusses the embryology of the eye. It notes that the eye develops from the ectoderm and mesoderm germ layers. The eye begins as optic vesicles that invaginate to form the two-layered optic cup. The inner layer forms the retina and outer forms the retinal pigment epithelium. Growth factors, homeobox genes, and neural crest cells regulate eye development. The optic cup, lens, vitreous body, iris, ciliary body, retina and other structures continue developing throughout gestation. Failure of structures to form properly can result in various congenital eye anomalies.
The eye develops from tissues originating from both the ectoderm and mesenchyme. By the fifth week of development, the optic cup and lens vesicle have formed from invaginations of the ectoderm and overlying surface ectoderm. The neural retina develops within the optic cup as the neuroblastic layers proliferate. The optic stalk contains fibers that will form the optic nerve. Additional structures including the iris, ciliary body, choroid, sclera, cornea and extraocular muscles arise from the surrounding mesenchyme and ectoderm. Failure of structures to develop properly can result in various congenital eye abnormalities.
1. Embryogenesis begins with fertilization and progresses through cleavage, blastocyst formation, and gastrulation to form the three germ layers.
2. The optic vesicle invaginates to form the optic cup, which will give rise to the retina. The lens placode forms the lens.
3. By 8 weeks gestation, the neural tube has closed and the eye has developed into three layers - the retina, lens, and surrounding mesenchyme tissues.
The eye develops from four sources: neuroectoderm of the forebrain, surface ectoderm of the head, mesoderm between the layers, and neural crest cells. The neuroectoderm forms the retina, iris, optic nerve. The surface ectoderm forms the lens. The surrounding mesoderm forms the vascular and fibrous coats. The neural crest forms the choroid, sclera, and cornea. The optic cup and lens vesicle form by the 4th week. The optic cup layers form the retinal pigment epithelium and neural retina. The optic stalk transforms into the optic nerve. The ciliary body and iris develop from the optic cup and surrounding mesenchyme. Congen
The document provides an overview of eye anatomy and development from embryology through childhood visual milestones. It describes the development of eye structures from the optic vesicle and lens placode in the embryo. Key structures of the adult eye are defined including the orbits, lids, anterior and posterior segments. The visual pathways and extraocular muscle innervation are also reviewed. Childhood visual development milestones from pupillary light reflex to coordinated eye movements and visual exploration are outlined.
anatomical consideration of development of eye from embryonic stage. gives insight into future anatomical and pharmacological basis of drug development in disorders of eye.
here are fully explaned eye embryology & after birth what changes happens in eye which are Prepared &
presented by Mr.jasmin modi & Mr.nehal lilawala under guidance of Mr manoj kahar
This document provides an overview of the anatomy and physiology of the lens. It discusses the embryological development of the lens from the surface ectoderm. Key anatomical structures include the lens capsule, epithelium, fibers forming the nucleus and cortex. The lens receives nutrients from the aqueous humor and maintains transparency through electrolyte balance and antioxidant glutathione. The physiology of accommodation and factors contributing to lens transparency are also summarized.
The development of the human eye begins around day 22 of gestation as the optic vesicle forms laterally from the prosencephalon. The optic vesicle invaginates and contacts the overlying surface ectoderm to form the lens placode. By day 33, the lens vesicle separates from the surface ectoderm. The optic vesicle then forms the double-layered optic cup, with the lens vesicle embedded within. Various ocular structures develop from the optic cup, surface ectoderm, and surrounding mesenchyme including the retina, lens, cornea, iris, ciliary body, and more. The development of the eye is complete by birth.
This document discusses the embryological development of the human eye. It begins with an overview of the objectives and presentation layout. It then covers general embryology topics like formation of germ layers and eye primordia. Specific structures are discussed like development of the lens from surface ectoderm, formation of the optic vesicle, and migration of mesenchymal cells in corneal development. Congenital anomalies that can result from defects in embryogenesis are also mentioned. The development of the anterior and posterior eye segments are outlined over two sessions.
Organogenesis is the process by which the three germ layers (ectoderm, endoderm, and mesoderm) form the internal organs. The development of the eye occurs through interactions between the lens placode and optic vesicle. The optic vesicle induces formation of the lens placode and positions the lens in relation to the retina. The optic vesicle then becomes the optic cup with two layers that differentiate into the pigmented retina and neural retina. The lens placode invaginates to form the lens.
The document provides information on the anatomy and physiology of the lens. It discusses the position, dimensions, surfaces, parts and zones of the lens. It describes the biochemistry of the lens including its water, protein, amino acid, carbohydrate and lipid content. It explains the metabolic activities of the lens such as glucose metabolism and protein synthesis and breakdown. It discusses permeability, transport mechanisms and the role of various components in maintaining lens transparency.
The document summarizes the anatomy and embryology of the lens. It discusses the gross anatomy, functions, embryological development from optic vesicles and lens placode, and structure of the lens including the capsule, epithelium, fibers, nucleus and zonules. It describes the aging changes that occur in the lens and various diseases that can affect it, including congenital disorders, cataracts, posterior capsular opacification, ectopia lentis and others. The document provides a detailed overview of the key anatomical structures and developmental processes involved in lens formation and function.
This document provides an overview of the human crystalline lens, including its embryology, anatomy, biochemical composition, physiology, and clinical significance.
The lens develops from surface ectoderm beginning around the 4th week of gestation. It progresses from a lens placode to a lens pit and then a lens vesicle, with cells differentiating into primary lens fibers and an embryonic nucleus. Secondary lens fibers are added throughout life from lens epithelial cells.
The adult lens is a transparent, biconvex structure held in place by zonules attached at the lens equator. It has a refractive power of 16-17 diopters that decreases with age. The lens is composed of a capsule enclosing epithelial cells at the anterior surface
Anatomy of crystalline lens by Dr. Aayush Tandon Aayush Tandon
The document summarizes the anatomy of the crystalline lens. It discusses the lens's structure, composition, dimensions, and surgical anatomy. Key points include:
- The lens is a transparent biconvex structure composed mainly of specialized cells and proteins. It helps focus light onto the retina to allow vision.
- Structurally, it has an outer lens capsule enclosing lens epithelium cells and elongated lens fibers in concentric layers. The fibers are arranged in a nucleus and surrounding cortex.
- Dimensions vary with age but the lens is roughly 10mm in diameter and weighs around 258mg in adults. It provides around 16-17 diopters of refractive power and accommodates vision changes.
- Surgically
The vitreous body develops in three stages - primary, secondary, and tertiary. It fills the vitreous cavity and is attached at the vitreous base, posterior lens capsule, optic nerve head, macula, and around blood vessels. The vitreous is composed of a central medullary portion and outer cortical portion. The cortical vitreous contains more collagen fibers and cells. The vitreous is attached to the retina by the internal limiting membrane and vitreoretinal interface.
Anatomy and embryology of crystalline lens DrBPdrbhushan17
This document provides an overview of the embryology and anatomy of the crystalline lens. It discusses how the lens forms from the lens vesicle which sinks from the surface ectoderm. The lens vesicle then develops into the lens as lens fibers elongate from the posterior wall. The lens fibers form the embryonic, fetal, and adult nuclei over time. The document also describes the detailed anatomy of the adult lens, including its capsule, epithelium, fibers organized into the nucleus and cortex. It notes the lens' role in the eye's optical system and ability to accommodate.
The document discusses the human lens. It begins with the embryology of the lens, describing primary and secondary fiber formation. It then discusses lens anatomy, including the lens capsule, epithelium, fibers, zones of the lens (nucleus and cortex). Accommodation and presbyopia are also summarized. The document provides details on lens sutures, topography, refractive power and structure. Homeostasis and apoptosis of lens epithelial cells are also covered. Key lens disorders mentioned include cataract and coloboma.
The lens is a transparent biconvex structure located behind the iris. It has slightly more curved posterior surface with radii of curvature of 10mm (anterior) and 6mm (posterior). The lens thickens with age from 3mm at birth to 6mm in older age. It focuses light onto the retina and its elasticity allows it to change shape for accommodation via the ciliary body. The lens is composed of transparent cells and fibers arranged in concentric layers surrounded by an elastic capsule.
ANATOMY & EMBRYOLOGY OF LENS- Dr. Anuj Pawar.pptxDrAnujPawar
The lens begins developing very early in embryogenesis. By day 25, the optic vesicle forms from the forebrain. By day 27, the lens plate forms, becoming the lens pit by day 29. On day 33, the lens vesicle forms. On day 35, primary lens fibers develop. By 7 weeks, secondary lens fibers form the fetal nucleus, which develops between 2-8 months. The lens capsule surrounds the entire lens. The lens contains an anterior epithelium layer and inner cortex and nucleus zones, with the nucleus containing the oldest lens fibers in concentric layers.
The development of the eye begins around day 22 of gestation with the formation of the optic vesicle from thickenings in the neural plate. By day 27, the lens placode thickens over the optic vesicle and sinks to form the lens vesicle, detaching from the surface ectoderm by day 33. Primary lens fibers then elongate from the posterior wall of the lens vesicle to anchor in the basal lamina, growing toward the anterior epithelium. These primary fibers form the embryonic nucleus of the lens. Secondary lens fibers then form from the equatorial cells of the anterior epithelium, extending around the primary fibers. Cataracts present at birth or within the first year are called congenital or infantile
The eye develops from tissues originating from both the ectoderm and mesenchyme. By the fifth week of development, the optic cup and lens vesicle have formed from invaginations of the ectoderm and overlying surface ectoderm. The neural retina develops within the optic cup as the neuroblastic layers proliferate. The optic stalk contains fibers that will form the optic nerve. Additional structures including the iris, ciliary body, choroid, sclera, cornea and extraocular muscles arise from the surrounding mesenchyme and ectoderm. Failure of structures to develop properly can result in various congenital eye abnormalities.
1. Embryogenesis begins with fertilization and progresses through cleavage, blastocyst formation, and gastrulation to form the three germ layers.
2. The optic vesicle invaginates to form the optic cup, which will give rise to the retina. The lens placode forms the lens.
3. By 8 weeks gestation, the neural tube has closed and the eye has developed into three layers - the retina, lens, and surrounding mesenchyme tissues.
The eye develops from four sources: neuroectoderm of the forebrain, surface ectoderm of the head, mesoderm between the layers, and neural crest cells. The neuroectoderm forms the retina, iris, optic nerve. The surface ectoderm forms the lens. The surrounding mesoderm forms the vascular and fibrous coats. The neural crest forms the choroid, sclera, and cornea. The optic cup and lens vesicle form by the 4th week. The optic cup layers form the retinal pigment epithelium and neural retina. The optic stalk transforms into the optic nerve. The ciliary body and iris develop from the optic cup and surrounding mesenchyme. Congen
The document provides an overview of eye anatomy and development from embryology through childhood visual milestones. It describes the development of eye structures from the optic vesicle and lens placode in the embryo. Key structures of the adult eye are defined including the orbits, lids, anterior and posterior segments. The visual pathways and extraocular muscle innervation are also reviewed. Childhood visual development milestones from pupillary light reflex to coordinated eye movements and visual exploration are outlined.
anatomical consideration of development of eye from embryonic stage. gives insight into future anatomical and pharmacological basis of drug development in disorders of eye.
here are fully explaned eye embryology & after birth what changes happens in eye which are Prepared &
presented by Mr.jasmin modi & Mr.nehal lilawala under guidance of Mr manoj kahar
This document provides an overview of the anatomy and physiology of the lens. It discusses the embryological development of the lens from the surface ectoderm. Key anatomical structures include the lens capsule, epithelium, fibers forming the nucleus and cortex. The lens receives nutrients from the aqueous humor and maintains transparency through electrolyte balance and antioxidant glutathione. The physiology of accommodation and factors contributing to lens transparency are also summarized.
The development of the human eye begins around day 22 of gestation as the optic vesicle forms laterally from the prosencephalon. The optic vesicle invaginates and contacts the overlying surface ectoderm to form the lens placode. By day 33, the lens vesicle separates from the surface ectoderm. The optic vesicle then forms the double-layered optic cup, with the lens vesicle embedded within. Various ocular structures develop from the optic cup, surface ectoderm, and surrounding mesenchyme including the retina, lens, cornea, iris, ciliary body, and more. The development of the eye is complete by birth.
This document discusses the embryological development of the human eye. It begins with an overview of the objectives and presentation layout. It then covers general embryology topics like formation of germ layers and eye primordia. Specific structures are discussed like development of the lens from surface ectoderm, formation of the optic vesicle, and migration of mesenchymal cells in corneal development. Congenital anomalies that can result from defects in embryogenesis are also mentioned. The development of the anterior and posterior eye segments are outlined over two sessions.
Organogenesis is the process by which the three germ layers (ectoderm, endoderm, and mesoderm) form the internal organs. The development of the eye occurs through interactions between the lens placode and optic vesicle. The optic vesicle induces formation of the lens placode and positions the lens in relation to the retina. The optic vesicle then becomes the optic cup with two layers that differentiate into the pigmented retina and neural retina. The lens placode invaginates to form the lens.
The document provides information on the anatomy and physiology of the lens. It discusses the position, dimensions, surfaces, parts and zones of the lens. It describes the biochemistry of the lens including its water, protein, amino acid, carbohydrate and lipid content. It explains the metabolic activities of the lens such as glucose metabolism and protein synthesis and breakdown. It discusses permeability, transport mechanisms and the role of various components in maintaining lens transparency.
The document summarizes the anatomy and embryology of the lens. It discusses the gross anatomy, functions, embryological development from optic vesicles and lens placode, and structure of the lens including the capsule, epithelium, fibers, nucleus and zonules. It describes the aging changes that occur in the lens and various diseases that can affect it, including congenital disorders, cataracts, posterior capsular opacification, ectopia lentis and others. The document provides a detailed overview of the key anatomical structures and developmental processes involved in lens formation and function.
This document provides an overview of the human crystalline lens, including its embryology, anatomy, biochemical composition, physiology, and clinical significance.
The lens develops from surface ectoderm beginning around the 4th week of gestation. It progresses from a lens placode to a lens pit and then a lens vesicle, with cells differentiating into primary lens fibers and an embryonic nucleus. Secondary lens fibers are added throughout life from lens epithelial cells.
The adult lens is a transparent, biconvex structure held in place by zonules attached at the lens equator. It has a refractive power of 16-17 diopters that decreases with age. The lens is composed of a capsule enclosing epithelial cells at the anterior surface
Anatomy of crystalline lens by Dr. Aayush Tandon Aayush Tandon
The document summarizes the anatomy of the crystalline lens. It discusses the lens's structure, composition, dimensions, and surgical anatomy. Key points include:
- The lens is a transparent biconvex structure composed mainly of specialized cells and proteins. It helps focus light onto the retina to allow vision.
- Structurally, it has an outer lens capsule enclosing lens epithelium cells and elongated lens fibers in concentric layers. The fibers are arranged in a nucleus and surrounding cortex.
- Dimensions vary with age but the lens is roughly 10mm in diameter and weighs around 258mg in adults. It provides around 16-17 diopters of refractive power and accommodates vision changes.
- Surgically
The vitreous body develops in three stages - primary, secondary, and tertiary. It fills the vitreous cavity and is attached at the vitreous base, posterior lens capsule, optic nerve head, macula, and around blood vessels. The vitreous is composed of a central medullary portion and outer cortical portion. The cortical vitreous contains more collagen fibers and cells. The vitreous is attached to the retina by the internal limiting membrane and vitreoretinal interface.
Anatomy and embryology of crystalline lens DrBPdrbhushan17
This document provides an overview of the embryology and anatomy of the crystalline lens. It discusses how the lens forms from the lens vesicle which sinks from the surface ectoderm. The lens vesicle then develops into the lens as lens fibers elongate from the posterior wall. The lens fibers form the embryonic, fetal, and adult nuclei over time. The document also describes the detailed anatomy of the adult lens, including its capsule, epithelium, fibers organized into the nucleus and cortex. It notes the lens' role in the eye's optical system and ability to accommodate.
The document discusses the human lens. It begins with the embryology of the lens, describing primary and secondary fiber formation. It then discusses lens anatomy, including the lens capsule, epithelium, fibers, zones of the lens (nucleus and cortex). Accommodation and presbyopia are also summarized. The document provides details on lens sutures, topography, refractive power and structure. Homeostasis and apoptosis of lens epithelial cells are also covered. Key lens disorders mentioned include cataract and coloboma.
The lens is a transparent biconvex structure located behind the iris. It has slightly more curved posterior surface with radii of curvature of 10mm (anterior) and 6mm (posterior). The lens thickens with age from 3mm at birth to 6mm in older age. It focuses light onto the retina and its elasticity allows it to change shape for accommodation via the ciliary body. The lens is composed of transparent cells and fibers arranged in concentric layers surrounded by an elastic capsule.
ANATOMY & EMBRYOLOGY OF LENS- Dr. Anuj Pawar.pptxDrAnujPawar
The lens begins developing very early in embryogenesis. By day 25, the optic vesicle forms from the forebrain. By day 27, the lens plate forms, becoming the lens pit by day 29. On day 33, the lens vesicle forms. On day 35, primary lens fibers develop. By 7 weeks, secondary lens fibers form the fetal nucleus, which develops between 2-8 months. The lens capsule surrounds the entire lens. The lens contains an anterior epithelium layer and inner cortex and nucleus zones, with the nucleus containing the oldest lens fibers in concentric layers.
The development of the eye begins around day 22 of gestation with the formation of the optic vesicle from thickenings in the neural plate. By day 27, the lens placode thickens over the optic vesicle and sinks to form the lens vesicle, detaching from the surface ectoderm by day 33. Primary lens fibers then elongate from the posterior wall of the lens vesicle to anchor in the basal lamina, growing toward the anterior epithelium. These primary fibers form the embryonic nucleus of the lens. Secondary lens fibers then form from the equatorial cells of the anterior epithelium, extending around the primary fibers. Cataracts present at birth or within the first year are called congenital or infantile
The eyeball is not a perfect sphere but an oblate spheroid. It has three coats - fibrous, vascular, and nervous. The fibrous coat is transparent in the front as the cornea and opaque in back as the sclera. The vascular coat supplies nutrition and consists of the iris, ciliary body, and choroid. The nervous coat is concerned with vision. The eyeball is divided into anterior and posterior segments, with the anterior containing the lens and aqueous humor-filled chambers and the posterior containing structures behind the lens.
1. The document provides an overview of ocular embryology, outlining the development of the eye and its structures from gestational weeks 4-8.
2. Key stages include formation of the optic vesicle and cup, lens placode and vesicle, and differentiation of structures like the retina, choroid, iris from surrounding tissue layers.
3. By the end of the fetal period at birth, most major ocular structures have developed, with some continuing to mature like the fovea in the postnatal period.
Eye development starts from 22nd day of gestation when the embryo is about 2 mm in length it is 8 somite stage. The eyeball and its related structures are derived from some primordial.
Eyeball is derived from three embryonic layers. These layers include: 1. surface ectoderm 2. neural ectoderm 3. mesoderm
The document discusses the embryology, anatomy, physiology and applied anatomy of the lens. It begins by describing the early embryonic development of the lens, including the formation of the lens vesicle from surface ectoderm. It then details the anatomy of the adult lens, including its layers of capsule, epithelium and fibers which make up the nucleus and cortex. The physiology section covers lens transparency, metabolism and accommodation. Finally, it briefly mentions some anatomical anomalies of accommodation such as presbyopia and paralysis.
The development of the human eye begins around day 22 of gestation with the outgrowth of the optic vesicle from the prosencephalon. The optic vesicle invaginates to form the optic cup, with the inner layer forming the retina and the outer layer forming the retinal pigment epithelium. The lens placode develops from surface ectoderm and invaginates to form the lens vesicle. Surrounding mesenchyme tissues differentiate to form various ocular structures. By approximately 33 days, the eye consists of the optic cup, lens, and surrounding tissues that will give rise to the iris, ciliary body, choroid, sclera, and other ocular components.
The third week of development is characterized by major events including the formation of the primitive streak, three germ layers, notochord, allantois, neural plate and tube, somites, and intra-embryonic coelom. Gastrulation occurs as epiblast cells migrate through the primitive streak, forming the definitive endoderm, mesoderm and ectoderm. The notochord develops from the primitive node and defines the embryonic axis. Chorionic villi also develop further with mesodermal cores and capillaries. Neurulation involves the formation and closure of the neural tube from the neural plate.
Embryology of eye- Anatomical ConsiderationsTanvi Gupta
The eye develops rapidly during gestation and in the first years of life. During the 4th-8th week of gestation, the optic vesicle forms and invaginates to become the optic cup, which later develops into the neural retina and retinal pigment epithelium. The lens placode also forms during this time. After birth, the eye continues growing, with the axial length increasing most in the first year of life. The retina and visual cortex also continue developing postnatally. Proper development of the eye and visual system during these critical periods is required for normal visual function.
The document summarizes the anatomy and embryology of the lens. It discusses:
- How the lens develops from the surface ectoderm forming the lens placode which sinks below the surface to form the lens vesicle.
- The optic cup surrounds the upper and lateral sides of the lens, leaving an opening (fetal fissure) on the inferior side.
- The anatomy of the adult lens, including its biconvex shape, dimensions, layers (capsule, epithelium, fibers), and refractive properties.
- The formation and layers of lens fibers, from primary fibers forming the embryonic nucleus to secondary fibers comprising additional nuclei layers over time.
This document provides an overview of the human crystalline lens, including its embryology, anatomy, biochemistry, physiology, and clinical significance. It begins with a brief introduction and then covers the lens's development from the surface ectoderm starting at around 4 weeks of gestation. It describes the formation of the lens placode, pit, and vesicle, as well as the primary and secondary lens fibers. The document discusses the lens's structural anatomy, dimensions, shape, weight, surfaces, and refractive properties in adults and how they change with age. It also reviews the lens's composition, including the capsule, epithelium, nucleus, cortex, and zonules. Finally, it mentions some clinical implications and congenital anomalies associated with
This document provides an overview of the anatomy and physiology of the human lens. It begins with a brief discussion of lens embryology, including the formation of the lens placode and vesicle. It then describes the microscopic structure of the adult lens, including the lens capsule, epithelium, and fibers. Key aspects of lens molecular biology are summarized, such as the predominant crystallin proteins and role of water. The document also reviews lens metabolism, with glucose being the primary energy source broken down via the glycolytic and sorbitol pathways.
This document provides information on the embryology, anatomy, and physiology of the lens. It discusses the developmental stages of the lens from the lens placode to the formation of the lens vesicle and fibers. The anatomy sections describe the layers and structures of the lens including the capsule, epithelium, fibers that make up the nucleus and cortex. The physiology section explains how the lens maintains transparency and focuses light through accommodation using active transport mechanisms and crystalline proteins. It also discusses metabolic pathways and anomalies that can affect accommodation.
The document summarizes eye development from embryogenesis through formation of ocular structures and appendages. It describes how the eye begins developing on day 22 before neural tube closure through formation of the lens placode, optic vesicle, optic cup, and retina. The lens, cornea, uvea, vitreous, retina, sclera, orbit, extraocular muscles, eyelids, and lacrimal gland all develop through contributions from ectoderm, mesoderm, and neural crest cells over gestational weeks 4-12.
The development of the human eye begins around 22 days when the embryo is about 2 mm long. The main components that form the eyeball are the optic vesicle, lens placode, and surrounding mesoderm. By the end of the fourth week, the optic vesicle bulges out to form the optic cup, with the proximal part forming the optic stalk. The surface ectoderm thickens over the optic vesicle to form the lens placode which then sinks below the surface to form the lens vesicle. Associated mesenchyme condenses and differentiates to form layers that will develop into structures like the cornea, sclera, iris, choroid and ciliary body.
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This document provides an overview of basic human embryology. It discusses that embryology deals with prenatal development from the period of fertilization to 8 weeks when the embryo becomes a fetus. During this time critical processes like cleavage, differentiation of the germ layers, implantation, formation of the placenta and organs occur. It then outlines the key developmental events and changes that occur in each of the three trimesters.
The document summarizes eye development from day 22 of gestation. Key steps include formation of the optic vesicle and stalk from the forebrain, which induce the surface ectoderm to form the lens placode. The optic vesicle then invaginates to form the optic cup. Mesoderm enters through the choroidal fissure to form hyaloid vessels and vitreous humor. The optic cup develops into the two layers of the retina while the optic stalk forms the optic nerve. PAX6 is the master regulatory gene for eye development. By 7 weeks, the optic nerve is myelinated and structures such as the iris, ciliary body, sclera, choroid, cornea and conjunctiva have
This document provides an overview of the six eye movement systems: fixation, vestibular, optokinetic, saccadic, smooth pursuit, and vergence. It describes the function of each system, including holding the eye steady during head movements (vestibular), tracking targets (optokinetic, smooth pursuit), and bringing the fovea onto targets (saccadic). The neural pathways and control centers in the brainstem and cortex that underlie each system are also summarized.
This document provides an overview of malaria, including its evolution and life cycle. It discusses the five Plasmodium species that cause malaria in humans and their transmission via mosquitoes. Globally, over 200 million cases of malaria occur annually, with most cases concentrated in sub-Saharan Africa and India. The document outlines the complex life cycle of the malaria parasite within humans and mosquitoes. It also describes the clinical presentation of malaria, from uncomplicated to severe forms such as cerebral malaria, and approaches to diagnosis and treatment, including various classes of antimalarial drugs.
Optical Coherence Tomography (OCT) is a high resolution 3D imaging technique that uses low coherence interferometry to visualize internal structures of the eye. There are two main types - time domain OCT which uses a scanning reference mirror, and Fourier domain OCT which uses a fast sweeping laser and fixed reference mirror. OCT is useful for examining retinal layers, monitoring disease progression and treatment response, and planning treatments. Images are interpreted based on reflectivity, and common pathologies like retinal detachment, macular holes, and cystoid macular edema are identifiable. Commercially, Cirrus HD-OCT provides quantitative measurements and deviation maps to analyze retinal nerve fiber layer and macular thickness. Anterior segment OCT also allows imaging of anterior chamber
This document provides an overview of gonioscopy, a technique used to examine the anterior chamber angle. It describes the anatomy visualized during gonioscopy including the iris, ciliary body band, scleral spur, trabecular meshwork, Schlemm's canal, and Schwalbe's line. Common indications for gonioscopy include evaluating narrow angles, glaucoma, angle recession, and anterior chamber anomalies. Direct gonioscopy is performed using a convex lens like the Koeppe lens which eliminates total internal reflection and allows visualization of angle structures.
Fungal keratitis is a fungal infection of the cornea that is common in developing nations. It is most often caused by filamentous fungi like Aspergillus, Fusarium, and Curvularia in tropical areas, and Candida species in temperate regions. Risk factors include corneal injury, topical steroid use, diabetes, and contact lens use. Symptoms include pain, blurred vision, photophobia, and corneal ulceration. Diagnosis involves corneal scraping and culture, though PCR is more rapid. Treatment consists of topical antifungals like natamycin, amphotericin B, or voriconazole, with systemic antifungals as adjunctive therapy for severe cases
This document provides information on bacterial keratitis including its definition, demographic data, predisposing factors, pathogenesis, symptoms, clinical presentation, diagnostic testing, and treatment. Bacterial keratitis is an infection of the cornea associated with a corneal infiltrate and epithelial defect caused by bacteria. It most commonly affects contact lens users and individuals with ocular trauma or surface disease. Clinical presentation depends on the causative organism, with Gram-positive cocci like staphylococci causing well-defined lesions and Gram-negatives like Pseudomonas typically progressing rapidly. Diagnosis involves slit lamp examination, staining, and cultures of corneal scrapings.
1. Visual acuity is a measure of the ability to resolve fine detail and is defined as the smallest object or angle that can be seen by an observer.
2. There are several types of visual acuity charts used to test visual acuity including Snellen charts, logMAR charts, and picture charts suitable for children. Snellen charts use letters of decreasing size while logMAR charts use a logarithmic progression of letters.
3. Factors that can affect visual acuity include stimulus characteristics, observer factors like retinal location and pupil size, and psychological factors. Visual acuity is measured through tasks that assess minimum resolution ability.
The document discusses various implantable intraocular pressure (IOP) sensors. It describes smart contact lenses with embedded sensors that can monitor IOP and other biomarkers in tears. The sensors use transparent graphene and metal nanowire electrodes. A second approach involves incorporating IOP sensors into the haptics of intraocular lenses, where the sensors would detect IOP changes capacitively. A third proposed method is a choroid-IOP sensor that could be fixed or sutured to the sclera surface to directly measure pressure changes at the choroid. The document reviews the potential for these implantable sensors to continuously monitor IOP for glaucoma diagnosis and management.
Muktapishti is a traditional Ayurvedic preparation made from Shoditha Mukta (Purified Pearl), is believed to help regulate thyroid function and reduce symptoms of hyperthyroidism due to its cooling and balancing properties. Clinical evidence on its efficacy remains limited, necessitating further research to validate its therapeutic benefits.
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Our backs are like superheroes, holding us up and helping us move around. But sometimes, even superheroes can get hurt. That’s where slip discs come in.
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These lecture slides, by Dr Sidra Arshad, offer a quick overview of the physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
6. Describe the flow of current around the heart during the cardiac cycle
7. Discuss the placement and polarity of the leads of electrocardiograph
8. Describe the normal electrocardiograms recorded from the limb leads and explain the physiological basis of the different records that are obtained
9. Define mean electrical vector (axis) of the heart and give the normal range
10. Define the mean QRS vector
11. Describe the axes of leads (hexagonal reference system)
12. Comprehend the vectorial analysis of the normal ECG
13. Determine the mean electrical axis of the ventricular QRS and appreciate the mean axis deviation
14. Explain the concepts of current of injury, J point, and their significance
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
8 Surprising Reasons To Meditate 40 Minutes A Day That Can Change Your Life.pptxHolistified Wellness
We’re talking about Vedic Meditation, a form of meditation that has been around for at least 5,000 years. Back then, the people who lived in the Indus Valley, now known as India and Pakistan, practised meditation as a fundamental part of daily life. This knowledge that has given us yoga and Ayurveda, was known as Veda, hence the name Vedic. And though there are some written records, the practice has been passed down verbally from generation to generation.
2. Presentation Layout
1. Introduction on general embryology
2. Ocular embryology
3. Milestone in the development in ocular structure
4. Congenital anomalies of the eye and its adnexa
26-06-2020 2
14. Embryological Term
1. Oocyte (L. Ovum = egg): Female germ or sex cells
produced by ovaries.
2. Sperm (Gr. Sperma = seed): Male germ cells produced by
testes.
3. Zygote: Cell formed by union of a sperm and secondary
oocyte (ovum). The zygote is the earliest stage of embryo
(i.e., the beginning of the new human being).
4. Conceptus: Product of conception, i.e., embryo along with
its extraembryonic membranes.
26-06-2020 14
15. Embryological Term cont’d…
5. Cleavage: Series of mitotic divisions of the zygote to form
early embryonic cells—the blastomeres.
6. Morula (L. Morus = mulberry): Solid ball of 12–32 cells
(blastomeres) formed 3–4 days after fertilization, just at
the time when embryo enters the uterus.
26-06-2020 15
16. Embryological Term cont’d…
7. Blastocyst (Gr. Blastos = bud, Kystis = bladder):
o It forms at late morula stage when fluid passes into
intercellular spaces between the inner and outer layers of
cells and forms a fluid-filled cavity.
o The blastocyst is divided into two parts: an outer layer called
trophoblasts and inner cell mass called embryoblast.
o The cavity of blastocyst (blastocele) separates the
trophoblast from the inner cell mass except for a small area
where they are in contact.
26-06-2020 16
17. Embryological Term cont’d…
8. Implantation: Attachment and subsequent embedding of
blastocyst into uterine endometrium, where it develops
during gestation. Implantation occurs between fifth and
seventh day after fertilization.
9. Gastrulation: Formation of three germ layers (ectoderm,
mesoderm, and endoderm) in the embryo. It is the most
characteristic event during the third week of gestation.
10.Neurulation (Gr. Neuron = nerve): Process by which neural
plate forms the neural tube.
26-06-2020 17
18. Embryological Term cont’d…
11.Embryo (Gr. Embryon): Developing human from
conception to eighth week in uterus. This period is called
embryonic period (or period of organogenesis). By the end
of this period primordia of all the major structures of the
body are formed.
12.Primordium (L. Primus = first + Ordior = to begin):
Beginning or first discernible indication of an organ or
structure.
13.Fetus (L. Unborn = offspring): Developing human from
ninth week to birth. During this period (fetal period),
differentiation and growth of the tissues and organs
formed during the embryonic period takes place.26-06-2020 18
19. Embryological Term cont’d…
14.Abortion (L. Aboriri = to miscarry): Expulsion of a
conceptus (embryo or fetus) before it is unable, i.e.,
capable of living outside the uterus.
15.Gestation (L. Gestatio = bearing, carrying in the womb):
The duration of embryo in the uterus from fertilization of
the ovum until delivery (the period of normal pregnancy).
26-06-2020 19
20. Embryologic Derivation of Ocular Structures
Surface ectoderm gives rise to:
Lens
Corneal epithelium
Conjunctival epithelium
Epithelium of eyelids and cilia, meibomian glands, and
glands of Zeis and Moll
Epithelium lining nasolacrimal system
Lacrimal gland and epithelial lining the lacrimal apparatus
26-06-2020 20
21. Embryologic Derivation of Ocular Structures cont’d…
Neural ectoderm gives rise to:
Retinal pigment epithelium
Neural retina
Optic nerve fibers
Neuroglia
Epithelium of ciliary body
Epithelium of iris
Iris sphincter and dilator muscles
26-06-2020 21
22. Embryologic Derivation Of Ocular Structures Cont’d…
Neural crest gives rise to:
Corneal stroma (which gives rise to Bowman’s layer)
Corneal endothelium (which gives rise to Descemet’s
membrane)
Most (or all) of sclera
Trabecular structures
Uveal pigment cells
Uveal connective tissue
Ciliary muscle
Meninges of optic nerve
Vascular pericytes
26-06-2020 22
30. Optic Cup and Lens Vesicle
Choroidal fissure develops on the inferior aspect of the optic cup and optic
stalk
Lens vesicle enters into the optic cup
Optic vesicle invaginate to form double layer optic cup
lens pits
Optic vesicle comes in contact with surface ectoderm; form lens placode
Proximal part connected to forebrain constricted to form optic stalk
Optic vesicle
Optic groove/sulcus
26-06-2020 30
42. Pre-embryonic Period (Fertilization To End Of 3rd Week)
Formation of the principle germinal layer
Formation of neural plate and neural groove
26-06-2020 42
43. Embryonic Period (Beginning Of 4th To End Of 8th Week)
22 Days:
Appearance of optic pits in the neural fold.
25 To 28 Days:
Invagination of primary optic vesicle
Beginning of lens placode formation
Condensation of mesoderm determining extraocular
muscles.
26-06-2020 43
44. 5th Week Of Embryonic Period
Full development of primary optic vesicle
Earliest appearance of the primitive and marginal zones of
the presumptive retina.
Beginning of invagination of optic vesicle to form optic cup
Formation of the lens pit
26-06-2020 44
45. 5th Week Of Embryonic Period Cont’d….
Ophthalmic artery emerges from the internal carotid
Development of embryonic fissure
Hyaloid artery emerges from the primitive dorsal
ophthalmic artery
Lens pits has developed into a closed vesicle in contact with
surface ectoderm.
Hyaloid artery enters the embryonic fissure and reaches up
to posterior pole of the lens vesicle.
26-06-2020 45
46. 6th Week Of Embryonic Period
Lens vesicle become hollow sphere detached from ectoderm
Hyaloid artery takes part in the formation of the posterior
part of the tunica vasculosa lentis.
Beginning of the closure of embryonic cleft in its mid-
portion.
26-06-2020 46
47. 6th Week Of Embryonic Period Cont’d….
Second stage of retinal differentiation with formation of
primitive inner nuclear layer.
Formation of lens fibers from posterior epithelial cells of
lens vesicle.
Almost complete closure of embryonic fissure except at
anterior and posterior extent.
Optic nerve fibers travelling proximally into optic nerve.26-06-2020 47
48. 6th Week Of Embryonic Period Cont’d….
Beginning of development of secondary vitreous.
Choriocapillaris is completely formed.
Double layer of cells at the surface ectoderm forms the
corneal epithelium.
Orbital mesoderm begins to differentiate into extraocular
muscles.
26-06-2020 48
49. 7th Week Of Embryonic Period
• Distal end of the embryonic fissure is completely closed.
• Differentiation of inner and outer neuroblastic layers of
retina affected by appearance of transient fibre layer of
Chievitz at posterior pole.
• Rudiments of lids have developed into definite folds and the
fibers of the orbicularis oculi muscle begin to surround the
eye.26-06-2020 49
50. 7th Week Of Embryonic Period Cont’d….
Formation of anterior portion of tunica vasculosa lentis
Proximal remnant of embryonic fissure closed.
Beginning of nerve fibres crossing to form optic chiasma
Separation of corneal epithelium and endothelium by
acellular layer.
26-06-2020 50
51. 7th Week Of Embryonic Period Cont’d….
Nuclei of primary lens fibres disappears.
Lids folds gradually covers the eyes.
Canaliculi are present.
26-06-2020 51
52. 8th Week Of Embryonic Period
Optic chiasma is fully formed.
Penetration of acellular layer of cornea by mesoderm to
form corneal stroma.
Pupillary membrane is completely formed.
26-06-2020 52
53. 8th Week Of Embryonic Period Cont’d….
• Beginning of the anterior chamber can be recognized.
• All the motor nerves of the eye have reached the extraocular
muscles.
9th Week
• Ciliary body is begins to appear.
• Secondary vitreous is fully evident.
• Y-suture are now apparent in the embryonic nucleus of the
lens.
26-06-2020 53
54. 10th Week Of Embryonic Period
Zonule makes its appearance Bowman’s membrane is
forming.
Tenon’s capsule begins to form in the equatorial region.
Fibers of the orbicularis oculi are forming.
At the end of this period, optic tract have formed.
26-06-2020 54
55. 11th Week Of Embryonic Period
Macula begins to differentiate.
Differentiation of the occipital cortex appears.
The hyaloid system is maximally developed.
Rectus muscles are well differentiated and levator separates
from superior rectus.
26-06-2020 55
56. 4th Month
• Ciliary processes are fully formed.
• Secondary vitreous develops considerably.
• Lashes and gland of the lids appear and the plica is well formed.
• Tenon’s capsule is fully formed.
• Orbital walls are well developed.
26-06-2020 56
57. 5th Month
Myelination in the geniculate body is evident.
All layers of the choroid are now visible and melanoblasts
appear in its external portion.
Iris is fully developed.
Extraocular muscles have differentiated their tendinous insertion
Dural sheath of the optic nerve can be distinguished.
26-06-2020 57
58. 6th Month
Dilator pupillae begin to form.
Sphincter muscle of the pupil is fully differentiated.
Descemet’s membrane has appeared.
Anterior chamber angle is forming peripherally.
26-06-2020 58
59. 7th Month
Rods are differentiated in the retina.
Fovea become obvious.
Bergmeister’s papilla begins to atrophy.
Lacrimal canaliculi have opened on the lid margins and the
tarsus is well formed in the upper lids.
26-06-2020 59
60. 8th Months
All layer of the retina are extensively developed throughout.
Retinal vessels have reached the ora.
Fetal nucleus of the lens is complete.
Circulation of the anterior segment is complete.
Angle of anterior chamber is formed completely.
26-06-2020 60
61. 9th Month
• Diameter of the globe increase to 16 to 17mm.
• Except macula, general development of the retina is now
complete.
• Retinal vessels reach the periphery.
• Infantile nucleus of the lens begins to appear.
• Pupillary membrane and hyaloid vessels have disappeared.
• Formation of the physiologic cup of the disc begins.
26-06-2020 61
62. At Term
Apart from the fovea, the retina is fully developed.
Myelination of optic nerve fibre has reached lamina
cribrosa.
Coiled remnants of the hyaloid artery have attached
anteriorly up to the posterior lens capsule and float freely in
Cloquet’s canal.
Lacrimal glands are still undeveloped and tears are not
secreted.
Nasolacrimal duct has reached the nasal cavity but is
frequently separated from the inferior meatus by a
membrane.26-06-2020 62
63. Postnatal period
Orbit
Angle between orbital axes is 180 degree, at birth 71 degree
and 68 degree in adult.
Volume of the orbit at birth is 10.3 ml, 22.3ml at 1 year and
reaching the adult volume of 30 ml by 6-8 years.
Bony interorbital distance is hypoteloric due to absence of
frontal and ethmoid air cells which gives the appearance of
pseudostarbismus.
Optic canal at birth is actually a foramen but later becomes
canal, and at 1 year its length is 4mm.
26-06-2020 63
64. Lids And Lacrimal Apparatus
Vertical Dimensions
• Infants: 8-8.5mm
• 1-10 year: 9mm
Horizontal Dimensions
• At Birth: 18mm
• 1-10 year: rapid increase to adult level of 30mm
26-06-2020 64
65. Lacrimal System
Excretory and secretory functions of the lacrimal apparatus
are operational in most normal infants at birth.
Basal and reflex tear secretion in more than 80% infants at
birth, psychic and emotion tearing occurs several months
after life.
Development of NLD is complete at birth.
26-06-2020 65
66. IOP
Low at birth 7.8±0.4 mm Hg and increases 1mmHg/year for
5 years to reach adult level.
26-06-2020 66
67. Uveal Tract And Pupil
Dilator pupillae is poorly developed and does not reach
adult proportions until about the 5th year.
Iris stromal pigments develops after birth; so in white races
this tissue is initially light blue in colour for sometimes.
Pupillary light reaction is normal at birth.
Pars plana zone at birth is underdeveloped and pars plicata
is within just behind limbus.
26-06-2020 67
68. Lens
• Lens capsule increase in thickness especially anteriorly.
Hyaloid remnants at the posterior capsule gradually atrophy
through childhood.
• Nucleus: Although, the infantile nucleus is present at birth it
continues to grow by accumulation of new fibers up to
puberty.
• Cortex: the accretion of new fibers forms cortex, which
continues through out life.
26-06-2020 68
69. Macula
• Development of retina lags behind rest of the retina and thus
considerable changes occur after the birth.
• Differentiation of all layers proceeds during the first 4
months, at the end of which period the characteristic foveal
reflex is present on ophthalmoscopy.
• Macula is barely functional at birth. Histologically and
functionally mature by 4 years.
26-06-2020 69
71. Macula Cont’d…
Functional Maturity:
Visual fixation is present at birth and is well developed by 2
months.
Visual following is well developed by 3 months.
Differentiation of fovea is completed by 4 months and
characteristic foveal reflex is present on ophthalmoscopy.
26-06-2020 71
72. Optic Disc
Colour:
1. At birth, the disc is relatively and uniformly pale when
compared to the pink colour of the older disc.
2. However, this changes to the normal adult pink colour by about
6 months to 1 year of age.
Physiological Cupping:
1. Not seen in premature infants or underdeveloped full term
infants, such that the optic disc may appear grey at birth
resembling optic nerve atrophy.
26-06-2020 72
73. Peripheral Fundus
Still lacks the pigmentation of the adult.
The choroidal vessels are distinctly visible.
26-06-2020 73
74. Optic Nerve And Upper Visual Pathway
Myelination proceeds from occipital cortex downward and is
not complete until the end of the fourth month.
Myelination of the optic nerve begins during foetal life at
the lateral geniculate body and reaches the optic disc around
the time of birth.
Normally, the myelin does not extend anterior to the
cribriform plate.
26-06-2020 74
75. Refractive Status
• Term infant : +0.62 – 2.24D
• Increases up to 7 years of age
• Then decreases and stabilizes by 14-15 years
• Myopic shift:
- In hypermetropes - 0.12 D / year
- In myopes - 0.55 D / year
26-06-2020 75
76. Visual Acuity
• Postnatal maturation of visual pathway plays an important
role in development of vision.
• The 1st year of life remains the dynamic and plastic period for
visual development.
• Any pathology during this period will impair its development.
• The visual system remains malleable at least during first
decade of life, and attention to this plasticity is considered
for the prevention and treatment of amblyopia.
26-06-2020 76
77. Maturation Of Vision
• Optokinetic nystagmus is well developed at birth.
• Accommodation is well developed by 4 months.
• Ocular alignment becomes stable by 1 month.
26-06-2020 77
78. Levels Of Visual Acuity
Visual acuity 1 months 2 months 6 months Age at which 6/6 is
achieved
Optokinetic
nystagmus
6/120 6/60 6/30 20-30 months
Preferential
looking
6/120 6/60 6/30 24-36 months
VEP 6/120 6/60 6/6-6/12 6-12 months
26-06-2020 78
79. Stereopsis
• Development of stereopsis roughly parallels the
development of visual acuity. It can be demonstrated at 3 – 6
months of age and rapidly improves thereafter.
• Stereopsis ( titmus ) at adult level is achieved by 7 yrs.
26-06-2020 79
80. Visual Fields
Using suitable kinetic perimetry, the monocular visual fields
in new-borns extend 28 degrees to left and right of the
vertical meridian, and 11 degrees above and 16 degrees
below the horizontal meridian.
Rapid expansion in dimension of the visual fields follows,
and at 1 year of age the superior visual field is comparable to
that of adults.
By 10 years of age, adult visual field size is attained.
26-06-2020 80
81. Eye Movements
Initially, eye movements are irregular and not conjugate.
But by 5 – 6 weeks, the eyes can follow a light over a
considerable range.
Pursuit of small objects occurs at about 3 months and
transition from reflex to conscious fixation becomes
apparent; but conjugate fixation is not accurate until about 6
months, until convergence is established.
Corrective fusion reflexes are fully functional towards the
end of 1st year.
26-06-2020 81
82. Visual Milestones
Age Visual Milestones
• 29 weeks Gestation Pupillary reaction to light
• 30 weeks G to Birth Dislike bright light
- turns to subdued light
• Birth - 1 week Fixation present
- Follow horizontally moving
targets –OKN and vestibular
eye movements well
developed.
- Visual acuity on Acuity cards
(6/120)
26-06-2020 82
83. Visual Milestones continued…
Age Visual Milestones
• 4 weeks – 8 weeks Fixation well developed
- Follows vertically moving
objects
- Fusion develops
- Watches mother’s face intently
for prolonged duration
- Watches toys held in front of
face
- Doll’s head eye movements
26-06-2020 83
84. Visual Milestones continued…
Age Visual Milestones
• 3 months Watches movements of own hands
- Reaches out to interesting
objects
- Prefers photographs, mirror
faces to patterns
• 4 months Foveal differentiation completed
Accommodation developed
26-06-2020 84
85. Visual Milestones continued…
Age Visual Milestones
• 5 months Blink response to visual threat
- Grasps object and explores with
finger
• 6 months - VEP acuity adult level (6/6)
- Stereopsis on PLT well
developed
- Fusional convergence well
developed
26-06-2020 85
86. Visual Milestones continued..
Age Visual Milestones
• 9 months Visual differentiation of objects,
picks up small objects
• 18 months Visual acuity (Acuity cards : (6/6)
• 3 years Vision 6/9 - 6/6 On Tumbling E /
HOTV (Recognition)
- Contrast Sensitivity adult level
• 5 – 7 years Stereopsis well developed
• 10 years End of critical period for
monocular deprivation (synapse
formation completed)26-06-2020 86