This ppt file belongs to Mr. Yonas Akalu one of my best instructors ...
Vision is by far the most used of the five senses and is one of the primary means that we use to gather information from our surroundings. More than 75% of the information we receive about the world around us consists of visual information.
The eye is often compared to a camera. Each gathers light and then transforms that light into a "picture." Both also have lenses to focus the incoming light. Just as a camera focuses light onto the film to create a picture, the eye focuses light onto a specialized layer of cells, called the retina.
The human eye is an organ which reacts to light and pressure. As a sense organ, the mammalian eye allows vision. Human eyes help to provide a three dimensional, moving image, normally coloured in daylight. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can differentiate between about 10 million colors[1] and is possibly capable of detecting a single photon.
structure of eye ball,eyeball is a specialized sense organ that helps us to understand our environment. It is a sensory unit composed of three parts: receptor, sensory pathway, and a brain center
The main parts of the human eye are The Conjunctiva,
Sclera,Choroid,
Cornea, Iris, Pupil,
Anterior Chamber,
Posterior Chamber, Aqueous humor, Lens, Vitreous humor, Retina,Macula and Optic nerve.
in this ppt we describe about anatomy of eyeball( cornea, sclera, choroid, iris, retina, ciliary body, vitreous etc..), dimension of the eyeball, coats of the eyeball.
complete information about the refractive errors due to the problem in the acomodation of eye lense , disturbed image formation in the retina, contains -types of disease condition .
Refractive error means that the shape of your eye does not bend light correctly, resulting in a blurred image. The main types of refractive errors are myopia (nearsightedness), hyperopia (farsightedness), presbyopia (loss of near vision with age), and astigmatism.
ocular anatomy fluid system glaucoma lens cataract phototransduction field visual acuity ocular movement errors of refraction light reflex accommodation corneal reflex visual pathway and its lesions
This ppt file belongs to Mr. Yonas Akalu one of my best instructors ...
Vision is by far the most used of the five senses and is one of the primary means that we use to gather information from our surroundings. More than 75% of the information we receive about the world around us consists of visual information.
The eye is often compared to a camera. Each gathers light and then transforms that light into a "picture." Both also have lenses to focus the incoming light. Just as a camera focuses light onto the film to create a picture, the eye focuses light onto a specialized layer of cells, called the retina.
The human eye is an organ which reacts to light and pressure. As a sense organ, the mammalian eye allows vision. Human eyes help to provide a three dimensional, moving image, normally coloured in daylight. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can differentiate between about 10 million colors[1] and is possibly capable of detecting a single photon.
structure of eye ball,eyeball is a specialized sense organ that helps us to understand our environment. It is a sensory unit composed of three parts: receptor, sensory pathway, and a brain center
The main parts of the human eye are The Conjunctiva,
Sclera,Choroid,
Cornea, Iris, Pupil,
Anterior Chamber,
Posterior Chamber, Aqueous humor, Lens, Vitreous humor, Retina,Macula and Optic nerve.
in this ppt we describe about anatomy of eyeball( cornea, sclera, choroid, iris, retina, ciliary body, vitreous etc..), dimension of the eyeball, coats of the eyeball.
complete information about the refractive errors due to the problem in the acomodation of eye lense , disturbed image formation in the retina, contains -types of disease condition .
Refractive error means that the shape of your eye does not bend light correctly, resulting in a blurred image. The main types of refractive errors are myopia (nearsightedness), hyperopia (farsightedness), presbyopia (loss of near vision with age), and astigmatism.
ocular anatomy fluid system glaucoma lens cataract phototransduction field visual acuity ocular movement errors of refraction light reflex accommodation corneal reflex visual pathway and its lesions
The Atlas of the eye is a B.sc. degree research
It contains three parts:
- Anatomy & Physiology of the eye
- Pathology & errors in the eye
- Photography of the eye
enjoy it!
This lecture includes anatomy and Physiology of Cornea, if u like it kindly share it with colleagues and like it. I will share more lectures related to eye anatomy and optometry.
Thank You.
The eye is our organ of sight. The eye has a number of components which include but are not limited to the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous.
ANATOMY & PHYSIOLOGY Lecturer: Tatyana V. Ryazantseva
2. Outer eye: Eyelids The eyelids fulfill two main functions: protection of the eyeball secretion, distribution and drainage of tears
3. Lid movement The levator extends from an attachment at the orbital apex to attachments at the tarsal plate and skin. ● The lids are securely attached at either end to the bony orbital margin by the medial and lateral palpebral ligaments. Trauma to the medial ligament causes the lid to flop forward and laterally, impairing function and cosmesis.
4. Innervation - Sensory innervation is from the trigeminal (fifth) cranial nerve, via the ophthalmic division (upper lid) and maxillary division (lower lid). - The orbicularis oculi is innervated by the facial (seventh) nerve. - The levator muscle in the upper lid is supplied by the oculomotor (third) nerve.
5. Blood supply and lymphatics The eyelids are supplied by an extensive network of blood vessels which form an anastomosis between branches derived from the external carotid artery via the face and from the internal carotid artery via the orbit.
6. Blood supply and lymphatics Lymphatic fluid drains into the preauricular and submandibular nodes. Preauricular lymphadenopathy is a useful sign of infective eyelid swelling (especially viral).
these slide are modified or upgraded from the slid belonging to this website.i had added some of the content.hope that it will be more helpful to you all.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
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
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!
These lecture slides, by Dr Sidra Arshad, offer a quick overview of 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 leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
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. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
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
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
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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
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
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
8. Lacrimal Gland
Located in the upper, outer portion of each orbit of the
eye
Lobulated exocrine glands secreting tears
9. Lacrimal Ducts
There are about 6 to 12 in number
They dump tears on the surface of the conjunctiva of
the upper lid through the palpebral part of the gland
10. Tear Film:
Lipid layer produced by the
meibomian gland (oil)(hydrophobic)
Aqueous layer produced by the
Lacrimal gland (spreading, control
of infectious agents)
The mucous layer produced by
microscopic goblet cells in the conjunctiva
(coating)
11. Conjunctiva
The conjunctiva is a mucous membrane lining the
eyelids and covering the anterior eyeball up to the edge
of the cornea.
Bulbar: covers the sclera
Palpebral: lines the inside of the upper and lower lids
12. Lid retractors
Responsible for opening the eyelids
levator palpebrae superioris muscle
Lower lid retractor
inferior rectus, extends with the inferior oblique
and insert into the lower border of the tarsal plate
15. Cornea and sclera
The cornea and sclera form a spherical shell
which makes up the outer wall of the eyeball.
16. Cornea and sclera
The sclera is :
- principally collagenous,
- avascular (apart from some vessels on its
surface)
- relatively acellular.
The cornea and sclera merge at the corneal
edge (the limbus).
17. The chief functions of the cornea
Are protection against invasion of
microorganisms into the eye
the transmission and focusing (refraction) of
light.
Screening out damaging ultraviolet (UV)
wavelength in sunlight
19. Epithelium
Made of epithelial cells
A thin layer that keeps the stroma dehydrated and
shields the eye while being able to provide nutrients
and oxygen to the cornea
It acts as a barrier to protect the cornea, resisting the
free flow of fluids from the tears, and
prevents bacteria from entering the epithelium and
corneal stroma.
20. Epithelium
Extremely sensitive to pain
Can regenerate itself if damaged from disorders such as:
Recurrent corneal erosion: characterized by the failure of
the cornea's outermost layer of epithelial cells to attach to
the underlying basement membrane
Epithelial basement membrane dystrophy: the epithelium's
basement membrane develops abnormally, causing the
epithelial cells to not properly adhere to it.
Diabetes mellitus: poor adhesion between epithelial cells
and their basement membrane
21. Bowman’s membrane
smooth, acellular, nonregenerating layer, located
between the superficial epithelium and the stroma in
the cornea of the eye.
Is transparent, composed of collagen, cannot
regenerate after damage and form scars as it heals
which can lead to vision loss
22. Stroma
Lies beneath
Bowman’s membrane
Is composed primarily
of water (78%) and
collagen (16%), keratocytes
Giving the cornea its strength, elasticity and form
Fairly dehydrated which contributes greatly to the
light-conducting transparency.
23. Descemet’s membrane
Is a protective barrier under the Stroma
Interiorly composed of collagen and posteriorly
made of endothelial
Can regenerate after injury
24. Endothelium
Monolayer cells lies under the Descemet’s
membrane.
Is responsible for regulating fluid and solute
transport between the anterior chamber and the
stroma
The endothelial pump is an energy-dependent
mechanism resulting in ion transported from
the stroma to the aqueous humor, creating an
osmotic gradient drawing water out of the
stroma
25. Endothelium
These cells don’t regenerate, if they are destroyed,
a corneal transplant is the only therapy. Where the
defective cornea is removed and another donor
cornea of similar diameter is implanted
26. Cornea and sclera
Refraction of light occurs because of the curved
shape of the cornea and its greater refractive
index compared with air.
The cornea is transparent because of the
specialized arrangement of the collagen fibrils
within the stroma, which must be kept in a
state of relative dehydration.
27.
28. Choroid:
Thin brown tissue
Highly vascularized
Provides nutrients and oxygen to the retina
The choroid is opaque making sure no light is
scattered from the sclera to the retina.
29. Ciliary Body
A thick tissue inside the eye composed of
ciliary processes and muscles
Highly vascularized
Continuous with the
choroid behind and
the iris in front
30. Ciliary Processes:
Secretes the aqueous humour in the posterior
chamber and from it to the anterior chamber
The fluid nourishes and oxygenates the cornea
and lens and then drains into the sclera via
Schlemm canal
31. Ciliary Muscles:
Ciliary muscles are the set of muscles
(meridional, oblique, sphincteric) that affect
the shape of the lens during accommodation.
32. Iris:
Colored portion of the eye positioned between
the cornea and the lens
Smooth radial muscles
The Sphincter papillae
The Dilatator papillae
37. Retinal Pigment Epithelium:
Sheet of melanin-containing epithelial cells lying
between the choroid and the neural portion
Which form a single layer extending from the
periphery of the optic disc to the Ora Serrata
epithelial cells that assist in the turnover of rods and
cones and prevent the scattering of light within the
eyeball due to the presence of melanin also works as a
barrier between the vascular system of the choroid and
the retina.
38. The neural portion of the retina:
composed of the 9 remaining layers that would
convert light into electrical impulses to be transmitted
to the thalamus
The neural portion is soft, translucent and purple (due
to the presence of Rhodopsin) which becomes opaque
and bleached when exposed to light.
Neurons in the retina are classified into different
categories
39. The Ganglion cell layer:
Transmits the visual packets received from the
photoreceptors to the brain for further processing
Highly concentrated in the Macula, less in the fovea
Retinal ganglion cells vary significantly in terms of their
size, connections, and responses to visual stimulation
but they all share the defining property of having a
long axon that extends into the brain. These axons form
the optic nerve
40. The bipolar cell layer:
Radially oriented neurons. Signal couriers between the
photoreceptors that react to light stimuli and the
ganglion cells, there are two types of bipolar cells Cone
bipolar and rod bipolar, receiving information from
their respective photoreceptors.
41. Photoreceptor layer:
Comprised of rod and cons neurons that converts light
to receptor potential.
The rods are responsible for identification of shapes
and movement and the discrimination between black
and white and are dense at the peripheral of the retina.
Cons neurons are responsible for color vision and for
high visual acuity in bright light; they are highly
concentrated in the fovea at the center of the macula
lutea.
42. Photoreceptor layer:
The photoreceptors have photopigments that when hit
by light goes thru structural change and triggers the
initiation of a receptor potential across the nerves.
The cone cells have three photopigments each one
interacts at different wavelength (red, green and blue),
The rod cells they only have Rhodopsin which are
essential for vision during dimmed light.
43. Receptor potential initiation in a
rod cell
Light isomerizes retinal, which activates Rhodopsin
that in turn activates a G protein called transducin
which in turn activates the enzyme phosphodiesterase
(PDE), this enzyme then detaches cyclic guanosine
monophosphate (cGMP) from Na+ channels in the
plasma membrane by hydrolyzing cGMP to GMP. The
Na+ channels close when cGMP detaches. The
membrane’s permeability to Na+ decreases and the rod
hyperpolarizes due to the added negativity in neurons.
This hyperpolarization decreases the release of the
neurotransmitter glutamate into the synaptic cleft
between rod and the subsequent bipolar.
44. ON-OFF mechanism
At dark, Neurotransmitter glutamate is maximally
released and the rods are depolarized consequently
the ON bipolar gets hyperpolarized and the OFF
bipolar depolarized.
In light, Neurotransmitter glutamate is minimal and
the rods are hyperpolarized consequently the ON
bipolar gets depolarized and the OFF bipolar
hyperpolarized.
Depolarizing bipolar cells results in the release of
neurotransmitters whereas hyperpolarization stops
this release.
45. Horizontal cells:
Inhibitory interneurons,
that help integrate and
regulate the input from
multiple photoreceptor
cells and are responsible
for regulating vision under
both bright and dim light.
46. Amacrine cells:
Interneurons in the retina
They are responsible for 70% of input to retinal
ganglion cells. The remaining 30% are regulated by the
amacrine cells but are handled by the bipolar cells.
47. Macula
Center of the posterior retina
responsible for fine central vision
has yellow pigment (xantophyll)
histologically empty space tends to the
accumulation of extracellular material that
cause thickening
48.
49. Anterior cavity
Anterior Chamber located between the cornea and the
iris
Posterior chamber located between the lens and the
iris
Filled with aqueous humor produced by ciliary
processes and rich in nutrient, and is a metabolic
exchange for the vascular tissue of cornea and lens
Increase in Intraocular Pressure leads to glaucoma
51. Vitreous Body
Clear, avascular, gelatinous body.
comprises 2/3 of the volume of
the eye.
99% water ; 1% hyaluronic acid
and collagen.
The vitreous is adherent to the retina at certain points,
particularly at the optic disc and at the ora serrata.
52. The Lens
a biconvex lens with an index of refraction of 1.336
attached to the ciliary process by zonular fibers.
Non-vascular, colorless and transparent
The lens consists of stiff, elongated, prismatic cells
known as lens fibers, very tightly packed together and
divided into nucleus, cortex and capsule.
53. The Lens
These fibers are rich with proteins known as crystallins
which are responsible for transparency and refractive
properties and elasticity
54.
55. Refraction of Light:
The cornea refracts 75% of the light
transmitted
The rest is done by the lens
Image is projected on the retina, inverted,
minimized and real.
56. Accommodation of the Lens:
The Lens is biconvex which intensifies the
focusing power
The lens is flexible and can change curvature to
accommodate according to light and object
distance
For far away objects: the zonule fibers provide
tension to the lens giving it an elongated shape
For close objects: ciliary muscles contract, relaxes
the tension of the lens leading to a rounder shape
59. Alignment of the Eyes:
Binocular vision: The two eyes field of vision overlap
and the image coincide creating a single impression
This is done by synced eye movements where both
eyes move simultaneously to maintain the overlap of
vision.
61. Fusion:
Is the power exerted by
the eyes to keep the position
of the eyes aligned so that
the fovea can project
the same point in space.
62. Eye Movement:
Controlled by extraocular
muscles
To the left: levoversion
To the right: dextroversion
Upwards: sursumversion
Downwards: deorsumversion
63. Range of Focus:
For distances greater than 20 feet no
accommodation is required by the lens, but as this
distance shortens the lens has to accommodate
and will thicken to clarify image.
64. Comparison between eye and
camera:
Eye Camera
Diaphragm to
control the
amount of light
that gets through
to the lens
the pupil, at the center of the iris,
in the human eye.
the shutter in a camera
Method of
sensing the image
the image is focused on the
retina
film or sensor chip is
used to record the image
Method of
focusing
the focal length of the eye is
adjusted to create a sharp image.
This is done by changing the
shape of the lens; a muscle
known as the ciliary muscle does
this job.
the lens has a fixed focal
length. If the object
distance is changed, the
image distance is adjusted
by moving the lens