This document provides an overview of the anatomy of the cornea. It discusses the cornea's embryology, structure, layers (epithelium, Bowman's layer, stroma, Descemet's membrane, endothelium), functions, transparency, blood and nerve supply, and the limbus. Key points include that the cornea provides over 70% of the eye's refractive power, has no blood vessels but receives its blood supply from vessels at the limbus, and maintains transparency through the ordered arrangement of its collagen fibrils and the pumping function of the endothelial cells. The limbus is described as the circumcorneal transition zone between the cornea and sclera.
The document discusses the anatomy and surgical applications of the limbus. It defines the limbus as the transitional zone between the cornea and sclera, containing the pathways for aqueous humor outflow. Histologically, it describes how the layers of the cornea and conjunctiva become continuous at the limbus. Surgically, it notes the anterior limbal border, blue limbal zone, mid-limbal line, posterior limbal border, and white limbal zone. The best site for cataract incisions is the mid-limbal line, while anterior or posterior incisions risk damage to underlying structures. The limbus contains stem cells that renew the corneal epithelium.
The document summarizes the anatomy and physiology of the eyelids. It describes the main parts of the eyelids including the palpebral aperture, lid margin, tarsal plate, conjunctiva and glands. It discusses the layers of the eyelids from anterior to posterior including the skin, subcutaneous tissue, muscle and conjunctiva layers. It also summarizes the blood supply, nerves and functions of the eyelids.
This document provides information on the anatomy and physiology of the cornea. It describes the layers of the cornea including the epithelium, Bowman's membrane, stroma, Dua's layer, Descemet's membrane, and endothelium. It discusses the transparency of the cornea, metabolic processes, drug permeability, wound healing, and the effects of contact lens wear on corneal physiology. The cornea has several specialized functions including refracting light and protecting the interior of the eye.
The document discusses the anatomy and physiology of aqueous humor dynamics. It describes the structures involved in aqueous humor formation, which occurs primarily through active transport by the non-pigmented ciliary epithelium. These include the iris, ciliary body, trabecular meshwork, Schlemm's canal, and collector channels. Aqueous humor is formed at a rate of around 2.3 μl/min through diffusion, ultrafiltration and secretion across the ciliary epithelium. Various factors influence aqueous humor production and outflow through the trabecular meshwork into episcleral veins.
This document provides an overview of the anatomy of the cornea including its dimensions, structures, physiology, and nerve supply. The cornea has 5 layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. It is avascular and transparent to allow for vision. The epithelium is stratified and squamous, the stroma contains collagen bundles, and the endothelium maintains deturgescence of the stroma. The cornea has important optical and protective functions for the eye.
Lens is a transparent, biconvex, crystalline structure placed between iris and the vitreous in a saucer-shaped depression, the patellar fossa. The lens is a crystalline structure that is avascular and is devoid of nerves and connective tissue
It consists of three distinct part:
Lens capsule
Anterior lens epithelium, and
Lens substance or lens fibres
The document discusses the anatomy and surgical applications of the limbus. It defines the limbus as the transitional zone between the cornea and sclera, containing the pathways for aqueous humor outflow. Histologically, it describes how the layers of the cornea and conjunctiva become continuous at the limbus. Surgically, it notes the anterior limbal border, blue limbal zone, mid-limbal line, posterior limbal border, and white limbal zone. The best site for cataract incisions is the mid-limbal line, while anterior or posterior incisions risk damage to underlying structures. The limbus contains stem cells that renew the corneal epithelium.
The document summarizes the anatomy and physiology of the eyelids. It describes the main parts of the eyelids including the palpebral aperture, lid margin, tarsal plate, conjunctiva and glands. It discusses the layers of the eyelids from anterior to posterior including the skin, subcutaneous tissue, muscle and conjunctiva layers. It also summarizes the blood supply, nerves and functions of the eyelids.
This document provides information on the anatomy and physiology of the cornea. It describes the layers of the cornea including the epithelium, Bowman's membrane, stroma, Dua's layer, Descemet's membrane, and endothelium. It discusses the transparency of the cornea, metabolic processes, drug permeability, wound healing, and the effects of contact lens wear on corneal physiology. The cornea has several specialized functions including refracting light and protecting the interior of the eye.
The document discusses the anatomy and physiology of aqueous humor dynamics. It describes the structures involved in aqueous humor formation, which occurs primarily through active transport by the non-pigmented ciliary epithelium. These include the iris, ciliary body, trabecular meshwork, Schlemm's canal, and collector channels. Aqueous humor is formed at a rate of around 2.3 μl/min through diffusion, ultrafiltration and secretion across the ciliary epithelium. Various factors influence aqueous humor production and outflow through the trabecular meshwork into episcleral veins.
This document provides an overview of the anatomy of the cornea including its dimensions, structures, physiology, and nerve supply. The cornea has 5 layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. It is avascular and transparent to allow for vision. The epithelium is stratified and squamous, the stroma contains collagen bundles, and the endothelium maintains deturgescence of the stroma. The cornea has important optical and protective functions for the eye.
Lens is a transparent, biconvex, crystalline structure placed between iris and the vitreous in a saucer-shaped depression, the patellar fossa. The lens is a crystalline structure that is avascular and is devoid of nerves and connective tissue
It consists of three distinct part:
Lens capsule
Anterior lens epithelium, and
Lens substance or lens fibres
The conjunctiva is a thin moist membrane that covers the outer layer of the eyeball and lines the inner surface of the eyelids. It is made up of different parts, including the bulbar conjunctiva covering the sclera, palpebral conjunctiva lining the eyelids, and conjunctival fornices in the upper and lower eyelid regions. The conjunctiva contains goblet cells that secrete mucus to lubricate the eye and protect the epithelial cells, and it receives its blood supply from the anterior ciliary arteries and its nerve supply varies by region.
The optic nerve has no myelin sheath and is surrounded by meninges. It transmits signals from the retina and has four parts - intraocular, intraorbital, canalicular, and intracranial. The optic nerve head contains zones like the superficial nerve fiber layer, prelaminar zone, lamina cribrosa, and retrolaminar region. The lamina cribrosa provides a blood supply and the nerve increases in diameter after passing through it. In glaucoma, retinal ganglion cell loss leads to cupping of the optic disc. The optic nerve receives blood supply from the ophthalmic and ciliary arteries. Dysfunctions can cause visual field defects, changes to acuity and
The document discusses the biochemistry of tears and the cornea. It describes the three layers of the tear film - the outer lipid layer secreted by meibomian glands, the middle aqueous layer secreted by lacrimal glands, and the inner mucin layer secreted by conjunctival goblet cells. The tear film nourishes the cornea, washes away debris, and prevents infections through its pH, osmolarity, proteins, and other components. The cornea stays clear through avascularity maintained by VEGF and water transport proteins.
The vitreous is a clear jelly-like structure that fills the vitreous cavity between the lens and retina. It is composed primarily of water along with collagen fibrils and hyaluronic acid which give it structure and elasticity. The vitreous develops in three stages - primary, secondary, and tertiary vitreous. It has three main regions - the hyaloid layer, cortical vitreous, and medullary vitreous. The vitreous provides optical clarity and acts as a scaffold that helps maintain the shape of the eyeball.
Anatomy and embryology of anterior chamber angle ppt newanupama manoharan
This document discusses the anatomy and embryology of the angle of the anterior chamber. It begins by defining the angle of the anterior chamber as the recess formed between the posterior surface of the cornea and anterior surface of the iris, which is the main pathway for drainage of aqueous humor. It then covers the embryology of eye development from the formation of the optic vesicle and stalk to the optic cup. The document also discusses conditions that affect the angle such as congenital glaucoma and posterior embryotoxon. Assessment techniques for the anterior chamber angle including gonioscopy, torchlight examination, and imaging modalities like UBM and OCT are provided.
Keratoconus is a non-inflammatory, progressive thinning and protrusion of the cornea that results in irregular astigmatism and decreased vision. It typically presents after puberty with no gender or racial predilection. Diagnosis is made based on corneal thinning, Fleischer ring, Vogt's striae, and irregular astigmatism seen on keratometry and topography. Mild cases are managed with spectacles while more severe cases require rigid gas permeable contact lenses, Intacs, or corneal transplantation.
The cornea develops from surface ectoderm, mesenchyme, and neural crest cells during embryogenesis. It has five layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The stroma comprises the majority of the cornea and contains tightly packed collagen fibrils for strength. The endothelium regulates hydration to maintain corneal transparency. Metabolic processes and the avascular nature of the cornea allow it to remain clear by preventing edema. The cornea refracts light, protects the eye, and contains nerves for sensation.
The document provides an overview of the physiology of the cornea, including its embryology, optical properties, metabolism, hydration, transparency, and wound healing. Key points include that the cornea has 5 layers and gets its oxygen from the atmosphere, aqueous humor, and limbal capillaries. It maintains transparency through ordered collagen fibrils and avascularity. Hydration is regulated by the endothelial pump and stromal proteoglycans. Wound healing involves epithelial migration, proliferation, and adhesion as well as stromal scarring and endothelial remodeling.
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.
The document discusses the anatomy and physiology of the lens. It begins with the embryological development of the lens from surface ectoderm and describes the formation of the lens placode, pit, and vesicle. It details the anatomical structures of the lens including the capsule, epithelium, fibers, and zonules. The document also discusses the biochemical composition and metabolic processes that maintain lens transparency. Finally, it covers age-related changes to the lens and clinical significance including cataracts.
This document provides an overview of the anatomy of the cornea. It begins with definitions and then discusses the embryology, gross anatomy, histological structures, blood and nerve supply of the cornea. The histological structures section describes the layers of the cornea in detail, including the epithelium, Bowman's layer, stroma, Dua's layer, Descemet's membrane, and endothelium. It highlights the composition, structure, and clinical significance of each layer. The document emphasizes the parallel arrangement of collagen fibrils in the stroma, which allows for easy dissection during corneal transplant surgeries.
The lens is a transparent, biconvex structure located between the iris and vitreous. It maintains clarity, refracts light, and provides accommodation. During development, the lens forms from the lens placode and vesicle. Lens fibers are produced from epithelial cells and elongate to fill the lens. The lens is encapsulated and avascular, relying on aqueous humor for nutrition. In aging, the lens becomes less elastic and refractive index changes, reducing accommodative power and increasing risk for conditions like cataracts and presbyopia. Diseases of the lens can be congenital or acquired and include cataracts, posterior capsular opacification, and ectopia lentis.
The eyelids develop from the frontonasal and maxillary processes during embryogenesis. They contain skin, muscle, fibrous tissue and glands that work together to protect the eye. The orbicularis oculi muscle helps with blinking while the levator palpebrae superioris muscle elevates the upper eyelid. The tarsal plates provide structure and the meibomian glands secrete oils to form the tear film. Blood vessels from the internal and external carotid arteries provide a rich blood supply to support the eyelids' functions.
The document summarizes tear film dynamics and the structure of the tear film. It describes the three layers of the tear film - the outer lipid layer derived from meibomian and other glands, the middle aqueous layer secreted by lacrimal glands, and the inner mucin layer secreted by conjunctival goblet cells. It discusses the functions of each layer and the role of the tear film in lubrication, protection, and maintaining a smooth optical surface on the cornea. The dynamics of tear secretion, formation of the tear film layers, retention, redistribution, evaporation, and drainage of tears is also summarized.
The document summarizes key anatomical structures and outflow pathways involved in aqueous humor drainage from the eye. It describes the transition from the trabecular meshwork to Schlemm's canal, noting structures like the scleral spur, Schwalbe's line, and trabecular endothelial cells. The trabecular meshwork consists of three layers - uveal meshwork, corneoscleral meshwork, and juxtacanalicular tissue. Aqueous humor drains through the trabecular meshwork into Schlemm's canal and collector channels before exiting into episcleral and conjunctival veins. The main outflow pathways are trabecular outflow, accounting for 85-95%
The orbits are bony sockets that house the eyeballs. Each orbit has several openings and walls. The walls include an inferior floor formed by the maxilla and zygomatic bones, a superior roof formed by the frontal bone, medial and lateral walls formed by several bones, and an apex formed by the sphenoid bone. The orbits contain the eyeballs, extraocular muscles, blood vessels and three cranial nerves: the optic nerve (CN II), oculomotor nerve (CN III), and abducens nerve (CN VI). Openings between the orbits and cranial cavities transmit these structures and other nerves and vessels.
Corneal metabolism
1. o Cornea requires energy for normal metabolic activities as well as for maintaining transparency and dehydration o Energy is generated by the breakdown of glucose in the form of ATP o Most actively metabolizing layer are epithelium and endothelium o Sources of nutrients : o Oxygen : mainly from atmosphere through tear film , with minor amount supplied by the aqueous and limbal vasculature o Glucose , amino acid, vitamins and other nutrients supplied to cornea by aqueous humor o Glucose also derived from glycogen stores in corneal epithelium o Epithelium consumes O2 10 times faster then stroma
2. o Three process or pathways – o Pentose shunt (Hexose monophosphate shunt) –occurs both in hypoxic and normoxic condition o Glycolysis (Embden meyerhof pathway) –anaerobic process , glucose / glycogen converted to pyruvate yeilding 2 ATPs o TCA or krebs or citric acid cycle- aerobic condition pyruvate is oxidized to yield 36 ATP, water, CO2.
3. o In normal conditions all the glucose consumed by the cornea o Glucose mostly come from aqueous humor o The rate of glucose consumption by the whole cornea is approx. 100 microgram/hr/cm2. o 1 mol. of glucose will be converted to the pyruvic acid and produced 2 molecules lactic acid and 2 mol. of ATP o In the krebs cycle, 1 mol. of glucose will utilize the pyruvic acid and O2 to produced 36 mol. ATP o Epithelium and endothelium will consume the oxygen
4. o The pentose phosphate pathway is used to metabolize five carbon sugars; one ATP and 2 NADH molecules are produced from oxidation of one glucose molecule o Produced intermediates for nucleic acid synthesis and some amino acids o This process will happen in hypoxic or normoxic condition o The purpose of glucose metabolism through the pentose shunt is the production of NADPH
The eyelids are composed of several layers including skin, muscle, orbital septum, fat and conjunctiva. The upper eyelid is raised by the levator palpebrae superioris muscle and Muller's muscle. The lower eyelid is retracted by the capsulopalpebral fascia. Several glands including the meibomian glands and glands of Zeis and Moll are located within the eyelids and help form the tear film. The orbicularis oculi muscle allows for eyelid closure and blinking. Together, the eyelid structures protect the eye and help spread tears across the surface of the eye.
Cornea is the clear front surface of the eye. It lies directly in front of the iris and pupil, and it allows light to enter the eye.
Cornea forms the transparent and anterior 1/6th of the external fibrous coat of the globe of the eyeball.
The cornea is the eye's most powerful structure for focusing light that provides approximately 65 to 75 percent of the focusing power of the eye.
The cornea has unmyelinated nerve endings sensitive to touch, temperature and chemicals; a touch of the cornea causes an involuntary reflex to close the eyelid.
anatomy and physiology of cornea-.pdf gfhhepicsoundever
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. It has five layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The stroma makes up around 90% of the cornea's thickness and contains regularly arranged collagen fibrils that provide strength and optimal light refraction into the eye. The cornea has no blood vessels and receives nutrients from the aqueous humor and surrounding limbal vasculature to maintain its avascular and transparent state.
The conjunctiva is a thin moist membrane that covers the outer layer of the eyeball and lines the inner surface of the eyelids. It is made up of different parts, including the bulbar conjunctiva covering the sclera, palpebral conjunctiva lining the eyelids, and conjunctival fornices in the upper and lower eyelid regions. The conjunctiva contains goblet cells that secrete mucus to lubricate the eye and protect the epithelial cells, and it receives its blood supply from the anterior ciliary arteries and its nerve supply varies by region.
The optic nerve has no myelin sheath and is surrounded by meninges. It transmits signals from the retina and has four parts - intraocular, intraorbital, canalicular, and intracranial. The optic nerve head contains zones like the superficial nerve fiber layer, prelaminar zone, lamina cribrosa, and retrolaminar region. The lamina cribrosa provides a blood supply and the nerve increases in diameter after passing through it. In glaucoma, retinal ganglion cell loss leads to cupping of the optic disc. The optic nerve receives blood supply from the ophthalmic and ciliary arteries. Dysfunctions can cause visual field defects, changes to acuity and
The document discusses the biochemistry of tears and the cornea. It describes the three layers of the tear film - the outer lipid layer secreted by meibomian glands, the middle aqueous layer secreted by lacrimal glands, and the inner mucin layer secreted by conjunctival goblet cells. The tear film nourishes the cornea, washes away debris, and prevents infections through its pH, osmolarity, proteins, and other components. The cornea stays clear through avascularity maintained by VEGF and water transport proteins.
The vitreous is a clear jelly-like structure that fills the vitreous cavity between the lens and retina. It is composed primarily of water along with collagen fibrils and hyaluronic acid which give it structure and elasticity. The vitreous develops in three stages - primary, secondary, and tertiary vitreous. It has three main regions - the hyaloid layer, cortical vitreous, and medullary vitreous. The vitreous provides optical clarity and acts as a scaffold that helps maintain the shape of the eyeball.
Anatomy and embryology of anterior chamber angle ppt newanupama manoharan
This document discusses the anatomy and embryology of the angle of the anterior chamber. It begins by defining the angle of the anterior chamber as the recess formed between the posterior surface of the cornea and anterior surface of the iris, which is the main pathway for drainage of aqueous humor. It then covers the embryology of eye development from the formation of the optic vesicle and stalk to the optic cup. The document also discusses conditions that affect the angle such as congenital glaucoma and posterior embryotoxon. Assessment techniques for the anterior chamber angle including gonioscopy, torchlight examination, and imaging modalities like UBM and OCT are provided.
Keratoconus is a non-inflammatory, progressive thinning and protrusion of the cornea that results in irregular astigmatism and decreased vision. It typically presents after puberty with no gender or racial predilection. Diagnosis is made based on corneal thinning, Fleischer ring, Vogt's striae, and irregular astigmatism seen on keratometry and topography. Mild cases are managed with spectacles while more severe cases require rigid gas permeable contact lenses, Intacs, or corneal transplantation.
The cornea develops from surface ectoderm, mesenchyme, and neural crest cells during embryogenesis. It has five layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The stroma comprises the majority of the cornea and contains tightly packed collagen fibrils for strength. The endothelium regulates hydration to maintain corneal transparency. Metabolic processes and the avascular nature of the cornea allow it to remain clear by preventing edema. The cornea refracts light, protects the eye, and contains nerves for sensation.
The document provides an overview of the physiology of the cornea, including its embryology, optical properties, metabolism, hydration, transparency, and wound healing. Key points include that the cornea has 5 layers and gets its oxygen from the atmosphere, aqueous humor, and limbal capillaries. It maintains transparency through ordered collagen fibrils and avascularity. Hydration is regulated by the endothelial pump and stromal proteoglycans. Wound healing involves epithelial migration, proliferation, and adhesion as well as stromal scarring and endothelial remodeling.
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.
The document discusses the anatomy and physiology of the lens. It begins with the embryological development of the lens from surface ectoderm and describes the formation of the lens placode, pit, and vesicle. It details the anatomical structures of the lens including the capsule, epithelium, fibers, and zonules. The document also discusses the biochemical composition and metabolic processes that maintain lens transparency. Finally, it covers age-related changes to the lens and clinical significance including cataracts.
This document provides an overview of the anatomy of the cornea. It begins with definitions and then discusses the embryology, gross anatomy, histological structures, blood and nerve supply of the cornea. The histological structures section describes the layers of the cornea in detail, including the epithelium, Bowman's layer, stroma, Dua's layer, Descemet's membrane, and endothelium. It highlights the composition, structure, and clinical significance of each layer. The document emphasizes the parallel arrangement of collagen fibrils in the stroma, which allows for easy dissection during corneal transplant surgeries.
The lens is a transparent, biconvex structure located between the iris and vitreous. It maintains clarity, refracts light, and provides accommodation. During development, the lens forms from the lens placode and vesicle. Lens fibers are produced from epithelial cells and elongate to fill the lens. The lens is encapsulated and avascular, relying on aqueous humor for nutrition. In aging, the lens becomes less elastic and refractive index changes, reducing accommodative power and increasing risk for conditions like cataracts and presbyopia. Diseases of the lens can be congenital or acquired and include cataracts, posterior capsular opacification, and ectopia lentis.
The eyelids develop from the frontonasal and maxillary processes during embryogenesis. They contain skin, muscle, fibrous tissue and glands that work together to protect the eye. The orbicularis oculi muscle helps with blinking while the levator palpebrae superioris muscle elevates the upper eyelid. The tarsal plates provide structure and the meibomian glands secrete oils to form the tear film. Blood vessels from the internal and external carotid arteries provide a rich blood supply to support the eyelids' functions.
The document summarizes tear film dynamics and the structure of the tear film. It describes the three layers of the tear film - the outer lipid layer derived from meibomian and other glands, the middle aqueous layer secreted by lacrimal glands, and the inner mucin layer secreted by conjunctival goblet cells. It discusses the functions of each layer and the role of the tear film in lubrication, protection, and maintaining a smooth optical surface on the cornea. The dynamics of tear secretion, formation of the tear film layers, retention, redistribution, evaporation, and drainage of tears is also summarized.
The document summarizes key anatomical structures and outflow pathways involved in aqueous humor drainage from the eye. It describes the transition from the trabecular meshwork to Schlemm's canal, noting structures like the scleral spur, Schwalbe's line, and trabecular endothelial cells. The trabecular meshwork consists of three layers - uveal meshwork, corneoscleral meshwork, and juxtacanalicular tissue. Aqueous humor drains through the trabecular meshwork into Schlemm's canal and collector channels before exiting into episcleral and conjunctival veins. The main outflow pathways are trabecular outflow, accounting for 85-95%
The orbits are bony sockets that house the eyeballs. Each orbit has several openings and walls. The walls include an inferior floor formed by the maxilla and zygomatic bones, a superior roof formed by the frontal bone, medial and lateral walls formed by several bones, and an apex formed by the sphenoid bone. The orbits contain the eyeballs, extraocular muscles, blood vessels and three cranial nerves: the optic nerve (CN II), oculomotor nerve (CN III), and abducens nerve (CN VI). Openings between the orbits and cranial cavities transmit these structures and other nerves and vessels.
Corneal metabolism
1. o Cornea requires energy for normal metabolic activities as well as for maintaining transparency and dehydration o Energy is generated by the breakdown of glucose in the form of ATP o Most actively metabolizing layer are epithelium and endothelium o Sources of nutrients : o Oxygen : mainly from atmosphere through tear film , with minor amount supplied by the aqueous and limbal vasculature o Glucose , amino acid, vitamins and other nutrients supplied to cornea by aqueous humor o Glucose also derived from glycogen stores in corneal epithelium o Epithelium consumes O2 10 times faster then stroma
2. o Three process or pathways – o Pentose shunt (Hexose monophosphate shunt) –occurs both in hypoxic and normoxic condition o Glycolysis (Embden meyerhof pathway) –anaerobic process , glucose / glycogen converted to pyruvate yeilding 2 ATPs o TCA or krebs or citric acid cycle- aerobic condition pyruvate is oxidized to yield 36 ATP, water, CO2.
3. o In normal conditions all the glucose consumed by the cornea o Glucose mostly come from aqueous humor o The rate of glucose consumption by the whole cornea is approx. 100 microgram/hr/cm2. o 1 mol. of glucose will be converted to the pyruvic acid and produced 2 molecules lactic acid and 2 mol. of ATP o In the krebs cycle, 1 mol. of glucose will utilize the pyruvic acid and O2 to produced 36 mol. ATP o Epithelium and endothelium will consume the oxygen
4. o The pentose phosphate pathway is used to metabolize five carbon sugars; one ATP and 2 NADH molecules are produced from oxidation of one glucose molecule o Produced intermediates for nucleic acid synthesis and some amino acids o This process will happen in hypoxic or normoxic condition o The purpose of glucose metabolism through the pentose shunt is the production of NADPH
The eyelids are composed of several layers including skin, muscle, orbital septum, fat and conjunctiva. The upper eyelid is raised by the levator palpebrae superioris muscle and Muller's muscle. The lower eyelid is retracted by the capsulopalpebral fascia. Several glands including the meibomian glands and glands of Zeis and Moll are located within the eyelids and help form the tear film. The orbicularis oculi muscle allows for eyelid closure and blinking. Together, the eyelid structures protect the eye and help spread tears across the surface of the eye.
Cornea is the clear front surface of the eye. It lies directly in front of the iris and pupil, and it allows light to enter the eye.
Cornea forms the transparent and anterior 1/6th of the external fibrous coat of the globe of the eyeball.
The cornea is the eye's most powerful structure for focusing light that provides approximately 65 to 75 percent of the focusing power of the eye.
The cornea has unmyelinated nerve endings sensitive to touch, temperature and chemicals; a touch of the cornea causes an involuntary reflex to close the eyelid.
anatomy and physiology of cornea-.pdf gfhhepicsoundever
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. It has five layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The stroma makes up around 90% of the cornea's thickness and contains regularly arranged collagen fibrils that provide strength and optimal light refraction into the eye. The cornea has no blood vessels and receives nutrients from the aqueous humor and surrounding limbal vasculature to maintain its avascular and transparent state.
The cornea is the transparent front part of the eye that transmits and focuses light. It has 3 main layers - an outer epithelial layer, a thick middle stromal layer made of collagen, and an inner single-cell endothelial layer. The cornea derives its strength and curvature from the orderly arrangement of collagen in the stroma. It remains transparent due to its regular structure without blood vessels and the deturgescent properties maintained by the endothelial pump. The cornea has a high metabolic rate powered by glucose and oxygen and is innervated by nerves for vision and protection.
The document summarizes the anatomy and structure of the cornea, conjunctiva, and sclera. It describes the five layers of the cornea (epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium) and provides details on the composition, thickness, cellular structure, and function of each layer. It also discusses corneal embryology, repair, innervation and blood supply.
The cornea is the transparent front part of the eye that allows light to enter. It has five layers - an epithelial layer, Bowman's layer, the stromal layer, Dua's layer, Descemet's membrane, and an endothelial layer. The stromal layer makes up most of the cornea's thickness and contains collagen fibrils that are responsible for the cornea's strength and transparency. The endothelial layer functions to pump fluid out of the stroma to maintain deturgescence and transparency. The cornea has no blood vessels and receives nutrients primarily from the aqueous humor and tear film. It heals rapidly through epithelial cell migration when wounded.
The cornea is the transparent front part of the eye that helps refract light. It has several layers including an epithelium, Bowman's layer, a thick stroma, Descemet's membrane, and an endothelium. The stroma makes up most of the thickness and contains collagen lamellae that provide strength and optical clarity. The cornea obtains oxygen from surrounding vessels and has a high density of nerves for protection. Its anatomy allows functions like refraction, protection, and nutrient exchange crucial for vision.
The document discusses the histology of the normal corneal layers and pathology in endothelial decompensation. It describes the five layers of the cornea - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The stroma makes up 90% of the corneal thickness and contains lamellae of collagen fibrils and keratocytes. Endothelial decompensation occurs when the endothelial pump fails, allowing stromal edema and clouding.
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The cornea is the transparent outer layer at the front of the eye. It is about 0.5 mm thick and has 5 layers - an epithelial layer, Bowman's layer, a thick stromal layer, Descemet's membrane, and a single layer of endothelial cells. The stroma makes up 90% of the thickness and contains collagen fibrils that give the cornea its shape and refractive power. The cornea has no blood vessels and receives nutrients from aqueous humor and tears.
The document summarizes key details about the anatomy and physiology of the cornea. It describes the cornea's layers, thickness, curvature, cell types, refractive power, transparency mechanisms, metabolism, innervation, and role in maintaining hydration. A new potential layer called Dua's layer is also mentioned. The summary is as follows:
The document describes the anatomy and physiology of the cornea, including its layers, cells, curvature, thickness, refractive power, and mechanisms of transparency and hydration. A potential new layer called Dua's layer is also discussed.
The cornea consists of 6 layers - epithelium, Bowman's layer, stroma, Dua's layer, Descemet's membrane, and endothelium. The stroma makes up most of the thickness and consists of collagen lamellae and keratocytes in a ground substance. The endothelium is a single layer of cells that regulates fluid movement. The cornea has no blood vessels but receives nutrients from limbal vessels and is innervated by nerves from the trigeminal nerve.
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 document describes the anatomy and physiology of the cornea. It discusses that the cornea is the transparent, avascular tissue on the front of the eye that helps transmit and refract light. It has five layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The stroma makes up 90% of the cornea thickness and contains collagen fibrils and keratocytes. The cornea has no blood vessels but receives its nerve supply from the ophthalmic division of the trigeminal nerve. It serves to transmit and refract light entering the eye and help maintain the integrity and hydration of the eyeball.
anatomyofthecornea-161101224539-converted.pptxArun Kumar A
The cornea is the transparent front layer of the eye that refracts light. It has five layers - an epithelial layer, Bowman's layer, a thick stromal layer, Descemet's membrane, and an endothelial cell layer. The stromal layer makes up most of the cornea's thickness and contains collagen fibrils that give it structure and strength to protect the delicate interior of the eye. The cornea has no blood vessels and receives nutrients from tears and surrounding tissues. It has detailed measurements and refractive properties that allow light to pass through and focus on the retina.
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 provides information on the anatomy and physiology of the cornea. It discusses the gross anatomy including the layers of the cornea - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The microanatomy and ultrastructure of each layer is described. Key points include the lamellar structure of the stroma providing transparency, regeneration of the epithelium from basal stem cells, and the theories behind corneal transparency relating to the structure of the stromal collagen fibers.
- The cornea is the transparent anterior wall of the eye and provides two-thirds of the eye's refractive power. It has key functions in vision, protection, and structural integrity.
- The cornea is composed of 5 layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The epithelium and endothelium are actively involved in wound healing and maintaining deturgescence of the stroma.
- Embryologically, the cornea derives from both surface ectoderm and neural crest cells. Its detailed anatomy and physiology allow it to fulfill its important optical and protective roles in the eye.
The document provides an overview of the anatomy of the cornea. It begins by introducing the cornea as the transparent outer layer of the eyeball that allows for vision. The summary is as follows:
1) The cornea consists of 5 layers - epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium.
2) The stroma makes up around 90% of the corneal thickness and contains collagen fibrils and keratocyte cells.
3) The cornea has no blood vessels and receives nourishment by diffusion from the aqueous humor and vessels at its edges.
4) Knowledge of corneal anatomy is important for diagnosing and treating eye diseases as
This document summarizes the anatomy and physiology of the cornea. It describes the cornea as transparent, avascular tissue that is approximately 11-12mm horizontally and 10-11mm vertically. It notes that the cornea contributes 74% of the eye's refractive power. The document then details the different zones of the cornea and describes the layers that make up the cornea, including the epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. It provides information on the cell types, thickness, composition and functions of each layer.
Basavarajeeyam is a Sreshta Sangraha grantha (Compiled book ), written by Neelkanta kotturu Basavaraja Virachita. It contains 25 Prakaranas, First 24 Chapters related to Rogas& 25th to Rasadravyas.
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- Video recording of this lecture in English language: https://youtu.be/kqbnxVAZs-0
- Video recording of this lecture in Arabic language: https://youtu.be/SINlygW1Mpc
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
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Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
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
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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.
3. INTRODUCTION
Defintion: Transparent, avascular, anterior coat of the eye that
covers the iris, pupil and anterior chamber being continuous with the
sclera at the periphery.
Forms anterior one-sixth of fibrous coat of the eyeball
Refractive power: Anterior surface of cornea has a refractory
power of +48D and it’s posterior surface of
about -5D. Hence the net refractory power of cornea is
+43D which is 3/4th of the total refractory power of the eye (+60D).
• Refractive index is 1.37
4. DIMENSIONS
• Anterior surface of cornea is horizontally
elliptical 11.75 mm. by 11 mm.
• Posterior surface of cornea is circular with
diameter of 11.5 mm.
5. DIMENSIONS ctd…….
• Cornea is 0.52 mm. thick at the center which
gradually increases to 0.67mm at the
periphery.
• The radius of curvature of the central part of
cornea is 7.8 mm anteriorly and 6.5 mm.
posteriorly.
6. TOPOGRAPHY
• Steeper in infants.
• Greater flattening nasally than temporally.
• Near the limbus, the curvature increases before entering the trough
like contour of limbal zone.
• Flattens on convergence.
• Knowledge of topography important for CL fitting
8. EMBROLOGY OF CORNEA
• Mesenchymal mass of neural crest origin is now considered to give rise to cornea , iris
and anterior chamber angle.
• Three waves of tissue come forward between surface ectoderm and developing lens,
from the developing undifferentiated mesenchymal mass of NCC origin to contribute to
structures of anterior segment origin
9.
10. EMBRYOLOGY: EPITHELIUM
• 40 days POG: Superficial squamous layer & a
basal cuboidal layer.
• 2-3rd month POG: Superficial cells increase in
size & are covered by microvilli & microplicae.
• 5-6 months POG: corneal epithelium attains Adult morphology
11.
12. EMBRYOLOGY: BOWMAN’S ZONE
• Not formed until 4th month POG.
• Always acellular.
• Superficial keratocytes synthesize & lay down the
ground substance & collagen.
• At this stage the hemidesmosomes & anchoring
filaments in the basal lamina are partially developed.
•By 26 wks they have an adult appearance
13. EMBRYOLOGY: STROMA
• 7 weeks POG: Anterior extension of mesenchymal cells
migrates btw epithelium and endothelium & contributes to
growth of stroma.
• Initially acellular but ingrowing cells differentiate to
keratocytes that secrete type 1 collagen & stromal matrix.
• Fibrils are organized as lamellae and successive lamellae are
formed.
• Posterior layers of stroma are confluent with the condensed
tissue of the future sclera.
14. EMBRYOLOGY: DM & ENDOTHELIUM
Formed from mesenchymal cells derived from neural crest , which are
situated at margins of rim of optic cup. These cells migrate into
developing eye beneath the basal lamina of corneal epithelium and
form primordial corneal endothelium
15. EMBRYOLOGY: DM & ENDOTHELIUM ctd…..
• At about 40 days of POG – corneal endothelium consist of 2 layered
flattened cells
• By 3rd month endothelium in the centre of cornea becomes a single
layer of flattened cells that rest on the interrupted basal lamina the
future DM
• Apices of endothelial cells are joined by zona occludens in the middle
of 4th month
• 6th months of gestation DM demarcated clearly
16. FUNCTIONS
Refraction - 70% of total refractory power of eye is due to
smooth surface tear film & regular anterior
Curvature (Power = +43.1D , RI = 1.376)
Contains IOP - Function of collagen fibres in stroma
Transparency - Mainly due to Corneal endothelium which
continuously pumps out excess water
Protection - Acts as mechanical barrier to external
noxious stimuli.
17.
18. EPITHELIUM
Epithelium type-Stratified squamous
non keratinized
Thickness-50-90 microns,
5-6 layers of nucleated cells.
Continuous with conjunctiva at limbus but devoid of goblet cells.
Consists of 5-6 layers of nucleated cells resting on a basal lamina, namely –
basal cells , wing cells , surface cells
19. BASAL LAYER
Deepest layer
Cells are arranged in palisade manner
Germinativelayer of epithelium
Cells are columnar with rounded heads & flat bases
Nucleus is oval & oriented parallel to long axis of the cell
20. WING CELLS
Second layer of epithelium (1-2 layers) Polyhedral cells
Convex anteriorly forming cap over basal cells & send processes
between them
Nucleus is oval & oriented parallel to corneal surface
21. SURFACE CELLS
Most superficial layer (2-3 layers)
Cells are polyhedral & become wider & flatter towards the surface
Flattened nuclei project backwards leaving the surface perfectly smooth
Most superficial cells are mostly hexagonal & exhibit surface microvilli /
microplicae
22. BASAL LAMINA
Secreted by basal cells.
•Made up of collagen (*Type7 & glycoprotein
•Structurally attached with the underlying Bowman’s layer by short anchoring
filaments forming anchoring plaques
•Cohesion between basal lamina & Bowman’s zone maybe loosened by lipid
solvents, edema or inflammation but it remains attached to basal cells.
•Thicker in periphery and in diabetes & certain corneal disorders
Thickened with old age.
23. EPITHELIAL TURNOVER
The germinative region lies at the limbus, the stem cells, and cells migrate at a very
slower rate (123 μm/week) to the centre of cornea.
The XYZ hypothesis:ThoftR. and Friend J. (1983) proposed on the basis of experimental
evidence ,that both limbal basal and corneal basal cells are the source for corneal
epithelial cells,and there is a balance among division, migration & shedding.
The corneal epithelium is maintained by a balance among sloughing (Z) of cells from
the corneal surface, cell division (X) in the basal layer and renewal of basal cells by
centripetal migration (Y) of new basal cells originating from the limbalstem cells.
24.
25. BOWMANS MEMBRANE
Modified region of anterior stroma
Acellular homogeneous zone
8 –14 μm thick
Ant. surface is smooth & parallel with corneal surface
It delineates the anterior junction between cornea and limbus
Perimeter delineates anterior junction btw the cornea & the limbus &
is clinically marked by summits of marginal arcades of
limbalcapillaries.
26. Ultrastructurallyit is a felted meshwork of fine collagen fibrils of
uniform size in a ground substance
Posteriorly it becomes blended & interweaving with fibrils of ant.
Stroma
Compact arrangement of collagen gives it great strength and relatively
resistant to trauma both mechanical and infective
Perforated in many places by corneal nerves.
Convex ridges may generate over surface if its tension is relaxed during
indentation, hypotonyor manipulation causes ant.cornealmosaic,
polygonal or chicken-wire pattern over surface
No regeneration and replaced by coarse scar tissue
27. STROMA
About 500 μm thick (about 90% of corneal thickness)
Two components : 1) Lamellae 2) Cells
stroma consists of regularly arranged lamellae of collagen bundles, lie in
proteoglycan ground substance.
In the anterior 1/3rd there is more interweave & some lamellae pass
forward to be inserted into Bowman’s layer
In the deep stroma lamellae form strap like ribbons which run
approxright angle to consecutive layers. Approx300 lamellae.
28. Interfibrillar separation is equal to the fibril diameter. This separation
decreases with age.
Precise ordering is responsible for transparency of the stroma.
CELLS-
1)Keratocytesmake up 2.5 –5% of the stromal volume and are responsible
for synthesis of collagen & proteoglycan during development &
maintaining it thereafter.
2) Other cells found in stroma occasionally: lymphocytes,macrophages and
very rarely polymorphonuclearlymphocytes.
29. DUA’S LAYER
Named after Dr.Harminder Dua, who
discovered it
Acellular layer between stroma & DM , 6-15 μ
thick
Consists of about 5-8 lamellae of type-1
collagen bundles
Bundle spacing is similar to stromal tissue but
devoid of keratocytes
Very strong layer
Can withstand upto200 kPa pressure
30. DESCEMET’S MEMBRANE
It is the basal lamina of corneal endothelium
First appears at 2nd month of gestation and synthesis continue
throughout adult life
Thickness –at birth :-3 –4 μm at childhood :-about 5 μm
at adult :-10 –12 μm
Acts as a strong resistant sheet
It thickens with age and in some corneal degenerative conditions
Major protein of DM is Type IV collagen
31. ENDOTHELIUM
It is a single layer of hexagonal, cuboidal cells attached posterior aspect of
DM
It is neuroectodermalin origin
Corneal endothelial cells production is relatively fixed
Endothelial cells density –about 6000cells/mm² at birth
26%lost in 1styear, Further 26% lost over next 11years
cell loss slows stabilizes around middle age about 2500 cells/mm²
If cells density falls upto500 cells/mm² corneal oedema develops and
transparency reduced
32. CORNEAL TRANSPARENCY
The cornea transmits nearly 100% of the light that enters it. Transparency achieved by –
1. Arrangement of stromal lamellae
Two theories –
i)Maurice(1957): The transparency of the stroma is due to the lattice arrangement of
collagen fibrils. He explained, because of their small diameter and regularity of separation,
back scattered light would be almost completely suppressed by destructive interference
ii) Goldman et al. (1968): He suggest, a perfect crystalline lattice periodicity is not always
necessary for sufficient destructive interference. He explained, if fibril separation and
diameter is less than a third of the wavelength of incident light, then almost perfect
transparency will ensue. This is the situation which obtains in normal cornea.
33. 2.Corneal epithelium & tear film
•Epithelial non-keratinization
•Regular & uniform arrangement of corneal epithelium
•Junctions between cells & its compactness and also tear film
maintain a homogenicityof its refractive index
3.Relative deturgescencestate of normal cornea
4.Corneal avascularity
5.Non myelenatednerve fibres
34. BLOOD SUPPLY
• Avascular
• Loops of anterior ciliary artery invade the
subconjunctival tissue at corneal periphery by 1mm.
• Many pathologic processes show corneal
vascularisation.
• Superficial vessels are bright red, arborescent and
may raise the epithelium
• Deep vessels are greyish red, run parallel and do not raise the
epithelium.
40. LIMBUS
Anatomically , the limbus refers to circumcorneal transition zone of
conjunctivo-corneal and corneoscleral
Junction
1.5 mm wide in horizontal plane and 2mm in the vertical plane.
Limbus is the weakest region in the corneoscleralenvelope.
41.
42. CONJUNCTIVOCORNEAL JUNCTION
At this point bulbar conjunctiva is firmly adherent to the underlying
structures
Epithelium becomes several layers thick here and arranged
irregularly at limbus
Limbal epithelial basal cells are arranged in a peculiar pattern of
palisade of vogt, containing stem cells
43. SCLEROCORNEAL JUNCTION
At this point transparent corneal lamellae becomes continuous with
the oblique , circular and opaque fibres of sclera
44. SURGICAL LIMBUS
Its 2mm wide circumcorneal transition zone between the clear cornea
on one side and the opaque sclera on the other side
45. BORDERS OF SURGICAL LIMBUS
Anterior limbal border- marked by insertion of conjunctiva and tenon’s capsule into
cornea , forms anterior border of surgical limbus
Mid limbal line-junction of blue and white zone overlies termination of Descemet’s
membrane
Posterior limbal border-lies 1mm posterior to mid limbal line. It overlies the scleral spur
and can only be seen with the use of sclerotic scatter illumination
46. ZONES OF SURGICAL LIMBUS
Blue limbal zone – translucent zone seen posterior to anterior limbal border
dissecting limbus free of conjunctiva and tenon’s capsule
Extent - superior quadrant – 1mm
Inferior quadrant– 0.8mm
nasal and temporal – 0.4mm
47. WHITE LIMBAL ZONE
Its 1mm wide whitish area lies between mid-limbal line and the posterior limbal
border
Overlies trabecular meshwork
Its width is constant in all quadrant 1mm , so surgical limbus is greatest in superior
quadrant where width of blue zone is 1mm