The retina is the light-sensitive tissue lining the back of the eye. It contains 10 layers including the retinal pigment epithelium, rods and cones, bipolar and ganglion cells. The retina is thinnest near the center and thickens toward the periphery. Key structures include the optic disc, macula with fovea for sharp central vision, and ora serrata marking the edge. The retina contains over 120 million light receptors and ganglion cells whose axons converge at the optic disc to form the optic nerve.
Each eyelid contains a fibrous plate, called a tarsus, that gives it structure and shape; muscles, which move the eyelids; and meibomian (or tarsal) glands, which secrete lubricating fluids. The lids are covered with skin, lined with mucous membrane, and bordered with a fringe of hairs, the eyelashes.
Each eyelid contains a fibrous plate, called a tarsus, that gives it structure and shape; muscles, which move the eyelids; and meibomian (or tarsal) glands, which secrete lubricating fluids. The lids are covered with skin, lined with mucous membrane, and bordered with a fringe of hairs, the eyelashes.
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anatomy of optic nerve and its blood supply and clinical corelation
Presentation Layout: optic nerve anatomy
Embryology of optic nerve
Introduction
Parts of optic nerve
Blood supply
Clinical significance
For Further Reading
Wolff’s Anatomy of the eye and orbit by Bron, Tripathi and Tripathi
Anatomy and Physiology of eye by A.K. Khurana 2nd edition
Comprehensive Ophthalmology by A.K. Khurana 5th edition
AAO- Fundamentals & Principles of Ophthalmology : sec 2
Walsh and Hoyt’s Clinical Ophthalmology
Internet
1. Introduction Gross anatomy Layers Blood supply, drainage and nerve supply
2. INTRODUCTION • Sclera forms posterior 5/6th of external tunic , connective tissue coat of eyeball. • it continues with duramater and cornea • Its whole surface covered by tenon’s capsule • Anteriorly covered by- bulbar conjunctiva • Inner surface lies in contact with choroid • With a potential suprachoroidal space in between
3. Equa THICKNESS OF SCLERA
4. • Thickness varies with individual, with age • Thinner- children, elder, F> M • Thickest posteriorly • Gradually becomes thinner when traced anteriorly • Thin at insertion of extraocular muscle
The tear film constitutes Three layers :- An outermost lipid (oily) layer An aqueous (watery) layer that makes up 90% of the tear film volume; and A mucin layer that coats the corneal surface.
3. To form smooth optical surface on cornea. To keep the surface of cornea & conjunctiva moist It serve as lubricant It transfer oxygen Provide antibacterial action Wash debris out It provides a pathway for WBC in case of injury
4. Functions of lipid layer Retards evaporation of tear film Prevents the overflow of tears
5. Function of Aqueous Layer Flushes, buffers and lubricates the corneal surface Delivers oxygen and other nutrients to the corneal surface Wash out debris Delivers antibacterial enzymes and antibodies such as lysozyme.
6. Functions of Mucin Layer Spreads tears over corneal surface. Protects the cornea against foreign substances . Makes corneal surface smooth by filling in surface irregularities
The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage. It consists of: The lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the human eye;it is a serous gland located in lacrimal fossa.
UVEA constitutes- middle vascular coat
• 3 parts- a)iris
b)ciliary body
c)choroid
• Developmentally,structurally and functionallyindivisible
• color varies from light blue to dark brown
EMBRYOLOGY
IRIS-
• Both layers of epithelium derived from
marginal region of optic cup (neuroectoderm)
• Sphincter and dilator pupillae- anterior
epithelium (neuroectoderm)
• Stroma and vessels- vascular mesoderm
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anatomy of optic nerve and its blood supply and clinical corelation
Presentation Layout: optic nerve anatomy
Embryology of optic nerve
Introduction
Parts of optic nerve
Blood supply
Clinical significance
For Further Reading
Wolff’s Anatomy of the eye and orbit by Bron, Tripathi and Tripathi
Anatomy and Physiology of eye by A.K. Khurana 2nd edition
Comprehensive Ophthalmology by A.K. Khurana 5th edition
AAO- Fundamentals & Principles of Ophthalmology : sec 2
Walsh and Hoyt’s Clinical Ophthalmology
Internet
1. Introduction Gross anatomy Layers Blood supply, drainage and nerve supply
2. INTRODUCTION • Sclera forms posterior 5/6th of external tunic , connective tissue coat of eyeball. • it continues with duramater and cornea • Its whole surface covered by tenon’s capsule • Anteriorly covered by- bulbar conjunctiva • Inner surface lies in contact with choroid • With a potential suprachoroidal space in between
3. Equa THICKNESS OF SCLERA
4. • Thickness varies with individual, with age • Thinner- children, elder, F> M • Thickest posteriorly • Gradually becomes thinner when traced anteriorly • Thin at insertion of extraocular muscle
The tear film constitutes Three layers :- An outermost lipid (oily) layer An aqueous (watery) layer that makes up 90% of the tear film volume; and A mucin layer that coats the corneal surface.
3. To form smooth optical surface on cornea. To keep the surface of cornea & conjunctiva moist It serve as lubricant It transfer oxygen Provide antibacterial action Wash debris out It provides a pathway for WBC in case of injury
4. Functions of lipid layer Retards evaporation of tear film Prevents the overflow of tears
5. Function of Aqueous Layer Flushes, buffers and lubricates the corneal surface Delivers oxygen and other nutrients to the corneal surface Wash out debris Delivers antibacterial enzymes and antibodies such as lysozyme.
6. Functions of Mucin Layer Spreads tears over corneal surface. Protects the cornea against foreign substances . Makes corneal surface smooth by filling in surface irregularities
The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage. It consists of: The lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the human eye;it is a serous gland located in lacrimal fossa.
UVEA constitutes- middle vascular coat
• 3 parts- a)iris
b)ciliary body
c)choroid
• Developmentally,structurally and functionallyindivisible
• color varies from light blue to dark brown
EMBRYOLOGY
IRIS-
• Both layers of epithelium derived from
marginal region of optic cup (neuroectoderm)
• Sphincter and dilator pupillae- anterior
epithelium (neuroectoderm)
• Stroma and vessels- vascular mesoderm
Retina : an overview
Seminar Presentation include Anatomy, Physiology, Pathology, Medical management and surgical management of retinal diseases and also latest updates. The Seminar was written and posted by famous ophthalmologist--
Dr Niraj Kumar Yadav
MBBS, MS Ophthalmology
FICM, FID, NDEP Liverpool UK
The retina is the sensory membrane that lines the inner surface of the back of the eyeball. It's composed of several layers, including one that contains specialized cells called photoreceptors.
Photoreceptor cells take light focused by the cornea and lens and convert it into chemical and nervous signals which are transported to visual centers in the brain by way of the optic nerve.
In the visual cortex of the brain (which, ironically, is located in the back of the brain), these signals are converted into images and visual perceptions.
The retina is the internal layer of the eyeball , which is a thin membrane having a purplish red color in living subject. This is a presentation by Dr. Shah-Noor Hassan regarding ANATOMY OF RETINA
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Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
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Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
2. • The retina is a thin, semitransparent,
multilayered sheet of neural tissue that
lines the inner aspect of the posterior two-thirds
of the wall of the globe.
• Thin delicate layer of nervous tissue
• Surface area of 266 mm2
• Extends from optic disc to ora serrata
3. Embryology
• The outer layer of the optic cup is known as the
pigmented layer of the retina.
• Development of the inner (neural) layer of the optic cup
is more complicated.
• The posterior four-fifths, the pars optica retinae, contains
cells bordering the intraretinal space that differentiate
into light-receptive elements, rods and cones.
• Adjacent to this photoreceptive layer is the mantle
layer, which, as in the brain, gives rise to neurons and
supporting cells, including the outer nuclear layer, inner
nuclear layer, and ganglion cell layer.
4.
5. Visible LAND MARKS of Human Retina
Optic Disc
Retinal Blood Vessels
Area centralis with fovea and foveola
Peripheral retina and ora serrata
Thickest near the optic disc
Thin towards the peripheral
6. OPTIC DISC:
Circular or slightly oval app. 1.5mn
In the central contains a depression known as Physiological
Cup
AREA CENTRALIS:
It is demarcated app. by upper and lower arcuate and temporal
retinal vessels.
Corresponds to app. 150 of the visual field and adopted for
accurate diurnal vision and colour discrimination.
It is divisible into fovea and foveola
FOVEA:
Center of area centralis 4mm temporal to the center of the optic
disc.
7.
8.
9. In this layer has there are no rods.
Cones are larger and abundant its central part consist of
cones and there nuclei covered by a thin internal limiting
membrane. All other layers are absent in this region.
In the center of the foveola there is tiny depression known
as umbo. It corresponds to foveolar reflex.
PERIPHERAL RETINA:
4 Regions
1. Near periphery: Circumscribed region of about 1.5mm
around the area centralis.
2. Mid periphery: Occupies 3mm wide zone around the near
periphery.
3. Far periphery: Extends from the optic disc 9-10mm on the
temporal side and 16mm on the nasal side in the horizontal
meridian.
10. 4. Ora serrata: Peripheral margin of the retina which consists
of dentate fringe. The retina ends here and ciliary body
stars.
Here sensory retina is firmly attached to vitreous and RPE
Servations are less developed temporally where cystic
degeneration is most common.
11. • Ora serrata marks the transition between the
attenuated Retina and Inner Columnar Non-
Pigment cells of Pars ciliariinues as retinae.
• The RPE continues anteriorly as the outer
cuboidal cell layer of the ciliary body.
• Beginning at a younger age the cystoid
degeneration starts at the outer plexiform layer ,
more marked on the nasal side.
• They extend between the inner and the outer
limiting membrane in elders and communicate
with the vitreous leading to Retinal Detachment.
17. RPE:
1. Outer most layer consists of single layer of hexagonal shape cells which
contain pigment.
2. It is firmly attached to underlying Bruch’s membrane and loosely attached to
layer of rods and cones.
3. Space bet. RPE and sensory retina is called sub retinal space. Separation of
RPE from sensory retina is called retinal detachment.
4. On electron microscopy the adjacent RPE cells are connected with each other
by tight junctions and constitute the outer blood retinal barrier. –Terminal bars.
5. Terminaln bars- ( Gap junctons , zonula ocludens and zonula adherens.
6. Zonula ocludens forms the external component of the Blood retinal Barrier.
7. Rest of intercellular space is filled by Extra cellular matrix-VERHOEFF’S
MEMBRANE in light microscope
18.
19.
20. FUNCTIONS:
• Imp. role in photo receptor renewal and recycling of Vit.A.
• Absorption of scattered light by Melanin Granules.
• Transport of nutrients and metabolites through extra retinal
blood barrier.
• Inter photo receptor matrix participates in retinal attachment
of the retina to RPE and facilitates Phagocytosis of the shed
discs of the outer cone segments.
• On the basal surface RPE cells produce type 4 collagen,
heparin sulphate and laminin which become incorporated in
lamina vitrea of Bruch’s membrane.
21.
22. LAYER OF PHOTO RECEPTORS:
There are about 120 million rods and 6.5mm cones.
1. End organs of vision which transform light energy to visual
impulse.
2. Rods contain photo sensitive substance rhodopsin which is
responsible for peripheral vision and vision of low
illumination.
3. Cones also contain a photo sensitive substain responsible
for central vision and colour vision.
4. Highest density of cones is at fovea.
5. Rods are absent at fovea and maximum below the optic
disc.
23.
24. STRUCTURE OF ROD CELL:
1. 40-60 μm long.
2. Outer segment is cylindrical. It contains flattened double
lamellae in the form of discs.
3. Discs various between 600 to 1000/rod cell. There are no
special attachments bet. discs or bet. discs and plasma
membrane.
4. Discs contain 90% of the visual pigment remaining is
scattered on plasma membrane.
5. Inner segment of the rod is thicker than the outer. It has two
regions.
a. Outer eosinophilic ellipsoid which contains more
mitocondria.
b. Myoid which contains glycogen as well as usual
organelles
25.
26.
27.
28. 6. A modified cilium connects the outer segment to inner
segment with 9+0 configuration i.e. 9 doublets around the
periphery with no central micortubule.
7. Outer rod fibre arises from the inner end of the rod which
passes through the external limiting memb. And swells into
a densely staining nucleus the rod granule which at its end
has an end buld called the rod spherule i.e. in contact with
cone foot.
CONE CELL:
1. 40 TO 80 μm largest at fovea shortest at periphery.
2. Outer segment of cone is conical and contains iodopsin.
3. Inner segment is similar to rod structures. Ellipsoid of cone
is very plump and contains a large number of mitochondria.
29. EXTERNAL LIMITING MEMBRANE:
Fenestrated memb. which extents from the ora serrata to
the edge of optic disc. Process of cones and rods pass
through this.
OUTER NUCLEI LAYER formed by nuclei of rods and cones.
Rod nuclei form the bulk of this layer. Number of rows of
nuclei and thickness of this layer where is from region to
region.
OUTER PLEXIFORM LAYER:
This layer contains the synapses bet. rod spherules and
cone pedicles with the dendrites of the bipolar cells and
processes of the horizontal cells. It marks the junction of the
end organs of vision and first order neurons in retina.
30.
31. INNER NUCLEI LAYER:
Consists of following cells:
• Bipolar cells
• Horizontal
• Amacrine
• The soma of the Muller’s
• Capillaries of the central retinal vessels
BIPOLAR CELLS:
• Neurons of first order of vision.
• Body of the bipolar cells consists entirely of nucleus, which
lies in the inner nuclear layers. There dendrites arborize
with the rod spherules and cone pedicles in outer plexiform
layer.
32.
33. 3. Under light microscopy nine types
a. Rod bipolar cells
b. Invaginating midget bipolar
c. Flat midget bipolar
d. Invaginating diffuse bipolar
e. Flat diffuse bipolar
f. On-centre blue cone bipolar
g. Off-centre blue cone bipolar
h. Giant bistratified bipolar
i. Giatn diffuse invaginating bipolar
34. HORIZONTAL NEURONS:
Consists of following cells:
Flat cells having neumerous horizontal associative and
neuronal interconnections between photo receptor and
bipolar cells in the outer plexiform layer.
Divided into 3 types- HI, HII and HIII.
AMACRINE CELLS:
Present in the inner most of this layer. They have a piriform
body and single process.
Forms connections with the axons of the ganglion cells.
35. MULLERS CELLS:
Nucleus and cell bodies are with in the inner nuclear layer.
They provide structural support and contribute to
metabolism of sensory retina.
Retina contains other glial cells like astrocytes, microglial
and oligodendrocytes.
INNER PLEXIFORM LAYER:
Consists of synapses bet. Axons of bipolar cells and
dendrites of ganglion cells.
36.
37. GANGLION CELL LAYER:
Cell bodies and nuclei of ganglion cells lie in this layer.
This layer is composed of single row of cells except in
macula where it is multi layer and on temporal side of disc it
has two layers.
It is absent in foveola
Classification of ganglion cells:
a. w, x, y ganglion cells
b. P & M ganglion cells
c. Off centre & on centre
d. Mono & Polysynaptic
38. NERVE FIBRE LAYER:
Consists of unmyelinated axons of the ganglion cells
which converge at the optic nerve head. Pass through the
lamina cribrosa and become ensheathed by myelin posterior
to the laminar.
Thickness where is from 0.5 to 2μm.
39. ARRANGEMENT OF
NERVE FIBRES IN THE
RETINA:
1. Fibres from the nasal half of
the retina come directly to the
optic disc as superior and
inferior radiating fibres (srf and
irf).
2. Fibres from the macular region
pass straight in the temporal
part of the disck as
papillomacular bundle (pmb).
3. Fibres from the temporal retina
arch above and below the
macular and papillomacular
bundle as superior and inferior
arcuate fibres (saf and iaf) with
a horizontal raphe in between.
40. ARRANGEMENT OF NERVE FIBRES OF THE OPTIC
NERVE HEAD:
Fibres form the peripheral part of the retina lie deep in the
retina but occupy the most peripheral (superficial) part of the
optic disc. While the fibres originating closer to the optic nerve
head lie superficially in the retina and occupy a more central
(deep) portion of the disc.
THICKENSS OF NERVE FIBRE LAYER AT THE DISC:
Thickness of the nerve fibre layer around the different
quadrants of the optic disc margin progressively increases in
the following order:
Most lateral quadrant (thinnest)
Upper temporal and lower temporal quadrant
Most medial quadrant
Upper nasal and lower nasal quadrant (thickest)
41. CLINICAL SIGNIFICANCE OF DISTRIBUTION AND
THICKNESS OF NERVE FIBRES AT THE OPTIC DISC
MARGIN:
1. Papilloedema appears first of all in the thickest quadrant
(upper nasal and lower nasal) and last of all in the thinnest
quadrant (most lateral).
2. Arcuate nerve fibres which occupy the superior temporal
and inferior temporal quadrants of optic nerve head are
most sensitive to glaucomatous damage, accounting for an
early loss in corresponding regions of visual field.
3. Macular fibres occupying the lateral quadrant are most
resistant to glaucomatous damage and explain the
retention of the central vision till end.
42. INTERNAL LIMITING MEMBRANE:
Consists of PAS positive true basement membrane that
forms the interface between retina and vitreous. The fibrils
of the vitreous merge with the internal lamellae of this
membrane. It consists of Collagen fibrils, Proteoglycans,
Basement Membrane, Plasma Membrane of the Muller cells
and possibly other glial cells of the retina.
43. BLOOD SUPPLY OF THE RETINA:
•Outer 4 layers of retina is supplied by (till outer nuclear layer)
choriocapillaries.
•The inner six layers gets its supply from central retinal artery which
is a branch of ophthalmic artery.
•The outer plexiform layer gets partly by both the above arteries.
•The fovea is avascular and is mainly supplied by choriocapillaries.
•The inner portion of the retina is perfused by branches of the central
retinal artery.
•In 30% of eyes ,a cilioretinal artery,branching from the ciliary
circulation ,supplies part of inner retina mainly The Macula Region.
•The retinal blood vessels maintain the inner blood-retinal barrier.This
physiological barrier is due to single layer of non-fenestrated
endothelial cells,whose tight junctions are impervious to tracer
substances such as fluorescein.
44.
45. •Retinal blood vessels lack an internal elastic lamina & a
continuous layer of smooth muscle cells.
•The retinal arteries are end arteries & have no
anastomoses.The only place where the retinal system
anastomoses is in the neighbourhood of lamina cribrosa.
•The veins of the retina unite to form Central retinal vein at the
disc, which follows the corresponding artery.
•The terminal fundus arterioles bend sharply and dip almost
vertically into the retina.
•In most of the Extramacular fundus- two retianal capillary
networks- a superficial and a deep.
•In parafoveal zone it is well developed and in 3 layers.
•A capillary free zone of 500miceo metre diameter in foveal
zone- FAZ.
46. Blood Retinal Barrier.
• Formed by the endothelial cells that are closely
bound together about the lumen by intercellular
junctions of zonula occludens type.
• These junctions normally prevent the free flow of
fluids and solutes.
• The endothelial cells are encircled by basement
membrane and which is surrounded by layer of
pericytes- which is further surrounded by
basement membrane.
• 1:1 ratio of pericytes and basement membrane
cells is normal.