The retina contains light-sensitive photoreceptor cells that absorb light and convert it into neural signals. Rods function better in low light and mediate peripheral and night vision, while cones require brighter light and help with color vision and central vision. Photoreceptors transmit signals through a series of inner retinal neurons to the optic nerve. The retina has different cell distributions and functions in different areas, with the high-acuity fovea containing only cones. Electroretinography tests evaluate the retina's response to light stimuli and help diagnose retinal diseases and conditions.
Anatomy of the Human Eye ( PDFDrive ).pdfRockyIslam5
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Anatomy of the Human Eye ( PDFDrive ).pdfRockyIslam5
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This is an Educational presentation on mechanism of vision. In this presentation layers of retina, process of transduction and electrical signals generation is well explained and finally optic nerve pathway is well illustrated.
This is an Educational presentation on mechanism of vision. In this presentation layers of retina, process of transduction and electrical signals generation is well explained and finally optic nerve pathway is well illustrated.
This deals with the types of Nystagmus both in pediatrics and adults, physiological and pathological types. Also the different diagnostic techniques and the management plan are presented in this.
A comprehensive summary of all the common corneal diseases starting from different types infective keratitis, non infective keratitis, corneal dystrophies, corneal ectasias to corneal degenerations.
A detailed review of all the types of tonometer and the technique with the principle is included. Will be very useful for both teachers and students of optometry & ophthalmology
It details about the sensory development, theories and the neural aspects of binocular vision development along with various tests involved to assess stereopsis.
This involves the various diseases of the conjunctiva. All the infective and non infective types of conjunctivitis are dealt here. This has the pathophysiology, signs, symptoms, diagnosis and management of these conditions. Conjunctival allergies and degenerations are also covered.
Deals with both dry eye and epiphora conditions. Dry eye includes Aqueous deficiency and evaporative varieties along with Meibomian gland dysfunction. Epiphora has both lacrimation and various anatomical and physiological blocks of the Nasolacrimal drainage system. This also includes the various tests required for diagnosing the different disorders. Chronic and Acute Dacryocystitis, Dacryoadenitis are also included.
A complete unit of the various diseases involving the orbit and the surrounding structures. It involves the unilateral and bilateral proptosis conditions. Also, the various proptosis etiologies involved in adults and children along with various tumors involving the orbit is also dealt with.
Medical Technology Tackles New Health Care Demand - Research Report - March 2...pchutichetpong
M Capital Group (“MCG”) predicts that with, against, despite, and even without the global pandemic, the medical technology (MedTech) industry shows signs of continuous healthy growth, driven by smaller, faster, and cheaper devices, growing demand for home-based applications, technological innovation, strategic acquisitions, investments, and SPAC listings. MCG predicts that this should reflects itself in annual growth of over 6%, well beyond 2028.
According to Chris Mouchabhani, Managing Partner at M Capital Group, “Despite all economic scenarios that one may consider, beyond overall economic shocks, medical technology should remain one of the most promising and robust sectors over the short to medium term and well beyond 2028.”
There is a movement towards home-based care for the elderly, next generation scanning and MRI devices, wearable technology, artificial intelligence incorporation, and online connectivity. Experts also see a focus on predictive, preventive, personalized, participatory, and precision medicine, with rising levels of integration of home care and technological innovation.
The average cost of treatment has been rising across the board, creating additional financial burdens to governments, healthcare providers and insurance companies. According to MCG, cost-per-inpatient-stay in the United States alone rose on average annually by over 13% between 2014 to 2021, leading MedTech to focus research efforts on optimized medical equipment at lower price points, whilst emphasizing portability and ease of use. Namely, 46% of the 1,008 medical technology companies in the 2021 MedTech Innovator (“MTI”) database are focusing on prevention, wellness, detection, or diagnosis, signaling a clear push for preventive care to also tackle costs.
In addition, there has also been a lasting impact on consumer and medical demand for home care, supported by the pandemic. Lockdowns, closure of care facilities, and healthcare systems subjected to capacity pressure, accelerated demand away from traditional inpatient care. Now, outpatient care solutions are driving industry production, with nearly 70% of recent diagnostics start-up companies producing products in areas such as ambulatory clinics, at-home care, and self-administered diagnostics.
CRISPR-Cas9, a revolutionary gene-editing tool, holds immense potential to reshape medicine, agriculture, and our understanding of life. But like any powerful tool, it comes with ethical considerations.
Unveiling CRISPR: This naturally occurring bacterial defense system (crRNA & Cas9 protein) fights viruses. Scientists repurposed it for precise gene editing (correction, deletion, insertion) by targeting specific DNA sequences.
The Promise: CRISPR offers exciting possibilities:
Gene Therapy: Correcting genetic diseases like cystic fibrosis.
Agriculture: Engineering crops resistant to pests and harsh environments.
Research: Studying gene function to unlock new knowledge.
The Peril: Ethical concerns demand attention:
Off-target Effects: Unintended DNA edits can have unforeseen consequences.
Eugenics: Misusing CRISPR for designer babies raises social and ethical questions.
Equity: High costs could limit access to this potentially life-saving technology.
The Path Forward: Responsible development is crucial:
International Collaboration: Clear guidelines are needed for research and human trials.
Public Education: Open discussions ensure informed decisions about CRISPR.
Prioritize Safety and Ethics: Safety and ethical principles must be paramount.
CRISPR offers a powerful tool for a better future, but responsible development and addressing ethical concerns are essential. By prioritizing safety, fostering open dialogue, and ensuring equitable access, we can harness CRISPR's power for the benefit of all. (2998 characters)
Telehealth Psychology Building Trust with Clients.pptxThe Harvest Clinic
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R3 Stem Cells and Kidney Repair A New Horizon in Nephrology.pptxR3 Stem Cell
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We understand the unique challenges pickleball players face and are committed to helping you stay healthy and active. In this presentation, we’ll explore the three most common pickleball injuries and provide strategies for prevention and treatment.
India Clinical Trials Market: Industry Size and Growth Trends [2030] Analyzed...Kumar Satyam
According to TechSci Research report, "India Clinical Trials Market- By Region, Competition, Forecast & Opportunities, 2030F," the India Clinical Trials Market was valued at USD 2.05 billion in 2024 and is projected to grow at a compound annual growth rate (CAGR) of 8.64% through 2030. The market is driven by a variety of factors, making India an attractive destination for pharmaceutical companies and researchers. India's vast and diverse patient population, cost-effective operational environment, and a large pool of skilled medical professionals contribute significantly to the market's growth. Additionally, increasing government support in streamlining regulations and the growing prevalence of lifestyle diseases further propel the clinical trials market.
Growing Prevalence of Lifestyle Diseases
The rising incidence of lifestyle diseases such as diabetes, cardiovascular diseases, and cancer is a major trend driving the clinical trials market in India. These conditions necessitate the development and testing of new treatment methods, creating a robust demand for clinical trials. The increasing burden of these diseases highlights the need for innovative therapies and underscores the importance of India as a key player in global clinical research.
QA Paediatric dentistry department, Hospital Melaka 2020Azreen Aj
QA study - To improve the 6th monthly recall rate post-comprehensive dental treatment under general anaesthesia in paediatric dentistry department, Hospital Melaka
Navigating the Health Insurance Market_ Understanding Trends and Options.pdfEnterprise Wired
From navigating policy options to staying informed about industry trends, this comprehensive guide explores everything you need to know about the health insurance market.
Navigating Challenges: Mental Health, Legislation, and the Prison System in B...Guillermo Rivera
This conference will delve into the intricate intersections between mental health, legal frameworks, and the prison system in Bolivia. It aims to provide a comprehensive overview of the current challenges faced by mental health professionals working within the legislative and correctional landscapes. Topics of discussion will include the prevalence and impact of mental health issues among the incarcerated population, the effectiveness of existing mental health policies and legislation, and potential reforms to enhance the mental health support system within prisons.
Global launch of the Healthy Ageing and Prevention Index 2nd wave – alongside...ILC- UK
The Healthy Ageing and Prevention Index is an online tool created by ILC that ranks countries on six metrics including, life span, health span, work span, income, environmental performance, and happiness. The Index helps us understand how well countries have adapted to longevity and inform decision makers on what must be done to maximise the economic benefits that comes with living well for longer.
Alongside the 77th World Health Assembly in Geneva on 28 May 2024, we launched the second version of our Index, allowing us to track progress and give new insights into what needs to be done to keep populations healthier for longer.
The speakers included:
Professor Orazio Schillaci, Minister of Health, Italy
Dr Hans Groth, Chairman of the Board, World Demographic & Ageing Forum
Professor Ilona Kickbusch, Founder and Chair, Global Health Centre, Geneva Graduate Institute and co-chair, World Health Summit Council
Dr Natasha Azzopardi Muscat, Director, Country Health Policies and Systems Division, World Health Organisation EURO
Dr Marta Lomazzi, Executive Manager, World Federation of Public Health Associations
Dr Shyam Bishen, Head, Centre for Health and Healthcare and Member of the Executive Committee, World Economic Forum
Dr Karin Tegmark Wisell, Director General, Public Health Agency of Sweden
2. Retina Structure
• Light sensitive layer is made of photo-
receptors: rods (120 millions) and cones (7
millions) which absorb the light.
• Plexiform Layer: nerve cells that process the
signals generated by rods and cones and
relay them to the optical nerve.
• Choroid: carries mayor blood vessels to
nourish the retina and absorb the light so
that it will not be reflected back (dark pupil!)
3. Rods and Cones
• Covers an area of 5 cm2. A baseball a mile
away gives an image covering one cone.
• Cones: for more precise vision, need strong
light. help to see colors. Mostly distributed
in the center of the retina (fovea).
• Rods: for peripheral and night vision.
Sensitive to light. Mostly distributed away
from fovea.
4.
5. Sensitivity
• Cones: slow, fine grain, like color film.
– Need high level of light (photopic condition, day)
– High density, high resolution.
• Rods: fast, coarse grain, black & white film
– Low level of light (scotopic condition, at night)
No color is obvious.
• Adaptation: Changing of retina sensitivity.
6. Singal Processing
• Trace the signal through
the retina:
• The retina is a seven-
layered structure involved
in signal transduction.
– Light enters from the GCL
side first, and must
penetrate all cell types
before reaching the rods
and cones.
– The outer segments of the
rods and cones transduce
the light and send the
signal through the cell
bodies of the ONL and out
to their axons.
OPL
Horizontal cells
DENDRITES OF
BIPOLAR CELLS
OUTER SEGMENTS OF RODS & CONES
Signal through the
cell bodies ONL
LIGHT
GCL Penetrate all cells to
reach rods & cones
7. • In the OPL photoreceptor axons contact the
dendrites of bipolar cells and horizontal
cells.
• Horizontal cells are interneurons which aid
in signal processing
• The bipolar cells in the INL process input
from photoreceptors and horizontal cells,
and transmit the signal to their axons.
8. • In the IPL, bipolar
axons contact
ganglion cell
dendrites and
amacrine cells,
another class of
interneurons.
• The ganglion cells of
the GCL send their
axons through the
OFL to the optic disk
to make up the optic
nerve.
• They travel all the way
to the lateral
geniculate nucleus.
OPTIC NERVE
OPTIC CHIASMA LGB
GCL
OFL Optic disc and
optic nerve
IPL
Bipolar axons contact
GANGLION CELL
DENDRITES &
AMACRINE CELLS
9. Fovea
• The fovea defines the center of the retina, and
is the region of highest visual acuity. The fovea
is directed towards whatever object you wish
to study most closely.
• In the fovea there are almost exclusively
cones, and they are at their highest density.
10. Processing Time
• Latency: it takes a bit time for the cells in
retina to respond to a flash of light.
• Persistence of response: the response does
not stop at the instant the flash stops.
– 1/25 second at low intensity, 1/50 second at high
intensity.
– The persistence allows as to see moving things
clearly.
12. Light activates rhodopsin
activates the G-protein Transducin
activates a phosphodiesterase enzyme (PDE)
converts cGMP GMP
cGMP closes ion channel, (the dark current channel)
Hyperpolarizes the photoreceptor
Phototransduction cascade
13. • Dark-current channel
– Open in the dark
– Closes in response to light
– Nucleotide-gated channel (opened by cGMP)
– Permeable to Na+
– Keeps photoreceptor Vm more positive than most
neurons
Steady release of neurotransmitter
14. In the Dark
Steady release
of
neurotransmitt
er
Inhibitory synapse
Hyperpolarized
With Light
Neurotransmitte
r release is
reduced
Inhibition is relieved
Depolarizes
Bipolar cell
Ganglion cell
To Optic Nerve
Excitatory synapse
transmitter
release
transmitter release
Photoreceptor
APs APs
Depolarized Hyperpolarized
15. ERG
• The clinical ERG is the recording of
the electrical potential waveform
generated by the total (pre-
ganglionic) retina in response to a
diffuse light stimulus.
• Performed in dark adaptation
• Reference electrode is attached to
forehead
16. • Negative ‘a wave’ – activities of
rods & cones.
• Positive (composite)‘b-wave’ –
from Muller cells in the bipolar
region(inner retinal layers).
• c-wave – retinal metabolism
(RPE).
• Peak amplitudes and latencies as
well as waveform shape are
considered in the interpretation
of the ERG.
• Monitors preganglionic retinal
activity so optic atrophy – N ERG.
• ERG - mass retinal response; an
isolated lesion of the macula
would not be expected to affect
this test as it contains only 7% of
total retinal cone population.
17. The Multifocal ERG
• Produces topographical maps of retinal
function
• Stimulus is scaled for variation in
photoreceptor density across the retina; at
fovea where receptor density is high
smaller stimulus element is used than in
periphery
• The information can be summarised in
form of a 3-D plot, resembling hill of vision
• Use : Any disorder that affects retinal
function.
18. CLINICAL APPLICATIONS
1. Vitamin A deficiency & xerosis
2. Retinitis pigmentosa & allied diseases e.g.
(a) Congenital Night Blindness
(b) Oguchi's Disease
(c) Retinitis punctate albicans
3. Prognosis in Cataract
4. Prognosis in Glaucoma
5. Detachment of retina
6. Systemic & retinal vascular conditions
7. Macular diseases
8. Malingering