Keratoconus is a degenerative ectatic condition of the cornea that causes steepening and thinning. It typically starts in adolescence and progresses until the third or fourth decade. Cross-linking involves applying riboflavin drops to the cornea, then exposing it to UV light to induce collagen cross-links, stiffening the cornea and halting progression. The standard protocol uses UV light at 3mW/cm2 for 30 minutes, but accelerated protocols with higher intensities for shorter times are being studied. Cross-linking stabilizes vision and reduces myopia by flattening the cornea, with effects continuing for up to 4 years.
Vitreous hemorrhage is the extravasation, or leakage, of blood into the areas in and around the vitreous humor of the eye.[1] The vitreous humor is the clear gel that fills the space between the lens and the retina of the eye. A variety of conditions can result in blood leaking into the vitreous humor, which can cause impaired vision, floaters, and photopsia.
It's an indepth presentation by Dr. Shah-Noor Hassan.
A surgical procedure featuring a partial thickness scleral flap that creates a fistula between AC and subconjunctival space for filtration of aqueous and creation of conjunctival bleb in an effort to lower IOP
Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...Bikash Sapkota
CLICK HERE TO DOWNLOAD FULL PPT ❤❤ https://healthkura.com/measurement-of-accommodation-of-eye/ ❤❤
Dear viewers Check Out my other piece of works at ❤❤❤ https://healthkura.com ❤❤❤
Measurement of Accommodation of eye:
Amplitude, Facility,
Relative Accommodation, Fatigue, Lag,
Dynamic Retinoscopy
Presentation Layout:
-Introduction to accommodation of eye
-Mechanism
-Components
-Measurement of accommodation of eye
- Amplitude
- Facility
- Relative accommodation
- Lag
-Dynamic Retinoscopy
Accommodation
-dioptric adjustment of the crystalline lens of the eye
- to obtain clear vision for a given target of regard
-process by which the refractive power of eye is altered
- to ensure a clear retinal image
For further reading
-Clinical Procedures in Optometry by J.D. Bartlett, J.B. Eskridge, J.F. Amos
-Primary Care Optometry by Theodere Grosvenor
-Borish’s Clinical Refraction by W.J. Benjamin
-Clinical Procedures for Ocular examination by Carlson et al
-American Academy of Ophthalmology
-Optometric Clinical Practice Guideline by American Optometric Association
-Internet
Follow me to get in touch with optometric and ophthalmic updates
Vitreous hemorrhage is the extravasation, or leakage, of blood into the areas in and around the vitreous humor of the eye.[1] The vitreous humor is the clear gel that fills the space between the lens and the retina of the eye. A variety of conditions can result in blood leaking into the vitreous humor, which can cause impaired vision, floaters, and photopsia.
It's an indepth presentation by Dr. Shah-Noor Hassan.
A surgical procedure featuring a partial thickness scleral flap that creates a fistula between AC and subconjunctival space for filtration of aqueous and creation of conjunctival bleb in an effort to lower IOP
Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...Bikash Sapkota
CLICK HERE TO DOWNLOAD FULL PPT ❤❤ https://healthkura.com/measurement-of-accommodation-of-eye/ ❤❤
Dear viewers Check Out my other piece of works at ❤❤❤ https://healthkura.com ❤❤❤
Measurement of Accommodation of eye:
Amplitude, Facility,
Relative Accommodation, Fatigue, Lag,
Dynamic Retinoscopy
Presentation Layout:
-Introduction to accommodation of eye
-Mechanism
-Components
-Measurement of accommodation of eye
- Amplitude
- Facility
- Relative accommodation
- Lag
-Dynamic Retinoscopy
Accommodation
-dioptric adjustment of the crystalline lens of the eye
- to obtain clear vision for a given target of regard
-process by which the refractive power of eye is altered
- to ensure a clear retinal image
For further reading
-Clinical Procedures in Optometry by J.D. Bartlett, J.B. Eskridge, J.F. Amos
-Primary Care Optometry by Theodere Grosvenor
-Borish’s Clinical Refraction by W.J. Benjamin
-Clinical Procedures for Ocular examination by Carlson et al
-American Academy of Ophthalmology
-Optometric Clinical Practice Guideline by American Optometric Association
-Internet
Follow me to get in touch with optometric and ophthalmic updates
Management of Keratoconus
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corneal-surgery
Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue (the graft). When the entire cornea is replaced it is known as penetrating keratoplasty and when only part of the cornea is replaced
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
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
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Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
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.
Title: Sense of Taste
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 structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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
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
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
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Keratoconus
1. Dr. K. Vasantha M.S., F.R.C.S., Edin
Director RIO Chennai (Rtd)
2. Keratoconus is an asymmetric, bilateral, progressive
ectatic condition of the cornea that can give raise to
severe visual impairment due to high, irregular myopic
astigmatism
Since different loci are implicated even in familial
keratoconus, it is considered to be a sporadic condition
involving external factors and stimuli
Usually starts at adolescence and progresses till third or
fourth decade. Affects both genders and all races
3. Atopy, vernal catarrh
Down’s
Retinitis pigmentosa
Turner’s
Connective tissue disorders like Marfan’s, Ehlers-Danlos,
osteogenesis imperfecta, pseudoxanthoma elasticum
Eye rubbing
Contact lens wear
Around 10% have a family history
4. Stromal thinning caused by a combination of increased
activity of proteinase enzymes decreased proteinase
inhibitors
There is redistribution of collagen which causes reduced
inter lamellar adhesion, lamellar inter lacing in the apex
of the cone and reduced number of lamellar insertions to
Bowman’s layer
Gross rearrangement of vertical and horizontal fibers in
the apex of cone
Breaks in BM are filled with collagen derived from stroma
5. This leads on to reduced biomechanical stability and
stretching of corneal tissues
Loss of correlation between anterior and posterior
corneal curvature
Abnormal keratocytes and matrix proteins affects the
attachment at the limbus
Lamellar bifurcations are opened up
6. Decrease in decorin, lumican, biglycan and keratocan (all
proteoglycans) is seen in keratoconus. These are needed
for a strong, refractive and transparent cornea.
Decrease in transforming growth factor beta which is
needed for contact between cells and other proteins
7. Astigmatism >5D
Asymmetric keratometry values.
Dioptric powers of ring 2 and 4 are considered
K1 or K2 more than 48 D
Central thickness <470 micro meter
8. Corneal asphericity > -0.50 micro meter. Human cornea
asphericity values ranges from -0.01 to -0.80 measured in
the 4.5 m optical zone
Epithelial remodeling causes movement of the
epithelium from the surface of the cone giving raise to a
doughnut pattern – early sign
9. A symmetrical bow tie will be horizontal in the against
the rule astigmatism and vertical in with the rule. It will
be diagonal in oblique astigmatism
In corneal irregularities an asymmetry is noted
It can superior steep, inferior steep, irregular, skewed
radial axis, round or oval
10. Ectasia should be suspected if the superior K value is
more than 2.5 D greater than inferior or the inferior value
is more than 1.5 D greater than upper
Displacement of the apex of the cornea leading on to
localized steepening
Skewing of the radial axis
Thinning of the cornea
11. 1: nipple cone has a diameter of 5mm or less. It is almost
circular and will be located in the central, paracentral or
more commonly inferonasal quadrant
2: Oval cone has a diameter of >5mm. Will be paracentral
or peripheral, usually inferotemporal
3: keratoglobus involves 75% of the cornea
12. When retinoscopy is done scissoring reflex will be seen
Fundoscopy will show a oil droplet sign
If thinning is gross the lower eye lid will bulge forward –
Munson's sign
Any other signs of atopy and vernal catarrh also must be
looked for
13. Vogt’s striae – these are vertical stress lines seen deep
in the stroma. Will disappear when gentle pressure is
applied
Fleischer’s iron ring- caused by deposition of
hemosiderin in the deeper parts of epithelium and
Bowman’s membrane at the base of the cone. Starts in
the lower quadrant and slowly becomes circular and
more sharp.
14. Rizzuti’s sign: when light is shown on the temporal libus
a bright reflex will be seen on the nasal limbus in
advanced cases
Thinning of cornea can be seen with a slit
Increased visibility of corneal nerves
15. This occurs when the Descemet’s membrane ruptures
due to extreme stretching
This leads on to corneal edema and severe drop in
vision.
After 6 to 8 weeks the edema comes down as the
endothelium covers the exposed area and secrete new
DM
The edges of the previously ruptured DM can be seen as
rolled out scrolls
16. Before the advent of topography keratoconus was
classified by Amsler as
Stage 1; high astigmatism, correctable with glasses
Stage2: astigmatism present but correctable with rigid
contact lenses
Stage 3: Cannot be corrected with glasses or contact
lenses
17. 1: Eccentric steepening, myopia, induced astigmatism or
both from 5 to 8 D with central K reading <48 D
2: Myopia, induced astigmatism or both from 5 – 8 D with
K reading < 53 D
3: Myopia and/or astigmatism 8 to 10 D, K > 53 D, no scar
and corneal thickness 300 to 400 micron
4: refraction not possible, K > 55 D, corneal scar,
thickness < 200
18. Here central keratometry value – central K
Inferior – superior index I- S
Astigmatism index ( measure of the regular corneal
astigmatism – simulated K1 and K2) AST
And the skewed radial axis SRAX which occurs in
keratoconus are taken in to consideration
KISA = (central K) x (I - S)x (AST) x (SRAX) x 100/300
19. In this classification the 3 m zone (both anterior ARC and
posterior curvature PRC)is centered on the thinnest part
instead of the center of the cornea. Scarring is also taken
in to consideration
Stage 0 : ARC >7.25mm/ <46.5D, PRC >5.90mm/ <57.25D,
thinnest pachy >490, > 20/20 no scar
Stage 1 : >7.05mm/<48D, >5.70mm/59.25D, >450 and
20/20 scar -,+,++
21. This is determined by noting changes in the thickness at
the thinnest point
Changes in the anterior and posterior curvature taken
from the central 3 mm optical zone centered on the
thinnest point
22. A display is made by combining the elevation and
pachymetric data.
Early change is easily noted by comparing the elevation
data of anterior and posterior surface to an enhanced
best fit sphere. Optical zone chosen here is 8 mm
omitting the 4 mm around the cone.
The difference map thus created is seen at the bottom of
Pentacam display
23. Green means change of less than 5 micro meters on the
anterior surface and 12 micro meter on the posterior
surface
Yellow denotes 5 – 7 for anterior and 12 – 16 for posterior
Red means > 7 anterior and >16 micro meters posterior
Posterior elevation of +15 at the thinnest point occurs in
less than 1% of normal cornea and hence should make
one suspect keratoconus
24. All the information needed for treating and monitoring
keratoconus patients are given in one display
If there is steepening on the tangential map,
Along with thinning on the pachymetry map
Elevation on the posterior float >10 micro meters,
keratoconus is suspected
25. The overall corneal thickness, location of the apex and
the thinnest point must be looked for.
The thickness in similar points in the superior and
inferior locations should not differ by more than 30micro
meters.
The general pachymetry should not differ by more than
10 micro meters between the two eyes.
In the normal cornea the central part will be uniformly
green
26. The displacement of the thinnest part also is significant.
When corneal thickness is measured by ultra sound
geometric center is chosen. This is not the thinnest point
in keratoconus. Measuring a single point is also useless.
Normally nasal side is thicker.
The average thickness on 1,2,3 ,4 and 5 mm rings are
used for noting the progression.
27. This has been developed using 56 parameters including
the corneal volume
This can detect forme fruste keratoconus accurately
28. It was found that dentists use ultraviolet light for
strengthening of gums.
It was also observed that natural cross linking occurred
in diabetics due to non enzymatic glycosylation
Aging cornea also stops protruding
Ultra violet light causes aging of collagen fibers
This led to the inception of cross linking in 1990 for
keratoconus
30. All flavins are thermostable, yet photosensitive. The
molecular changes occur at a very short time
Riboflavin is used as its alkylalloxazine structure helps it
to absorb a wide range of the light spectrum
Riboflavin is safe even if it is absorbed systemically
It is water insoluble. So the more soluble riboflavin – 5
phosphate is used.
Corneal epithelium will prevent adequate absorption of
riboflavin. Hence it has to be removed.
31. The wave length, irradiance and the exposure time
should be exact to make it safe.
The absorption peak of riboflavin is 370 nm.
As per Dresden protocol maximum amount of tissue
stiffening was seen to occur with 3 mW/cm2 of energy
for 30 minutes.
This is equal to a total energy of 5.4 J/cm2
32. To shorten the treatment time the parameters are
changed to higher intensities
Bunsen – Roscoe law of reciprocity : photochemical
effect will be similar as long as the total fluence remains
constant
But if the intensity is more than 45 mW/cm2 the
biomechanical stiffness drops.
So 10 mW/cm2 for 9 minutes is used
33. The demarcation line seen with anterior segment OCT is
at about 300 micro meters in standard protocol and at
230 micro meters in accelerated C3R
There is less decrease in keratocyte density with
accelerated C3R
There is also less disruption of the nerve plexus
34. Since the availability of oxygen is less in accelerated
cross linking, an one second on and one second off
technique is tried. It is not standardized yet. But with this
technique the cross linking is seen at a slightly deeper
level
35. For thin corneas hypotonic riboflavin can be used to
hydrate the cornea and thereby increase the thickness
Riboflavin soaked contact lens has been tried. But the
amount of riboflavin and type of contact lens are not
standardized. There is a problem of buckling of the lens
during the procedure.
The lenticule from SMILE procedure also is used to
increase the thickness. There is no problem of buckling
Customized toric, arcuate and concentric circles and
small diameter cone are also being tried
36. While there is an advantage of preserving the epithelium
and avoiding the scarring and delayed healing, the effect
is not as good as the conventional type.
Can be tried in children and low grade keratoconus
Problem is non availability of oxygen and poor
penetration of riboflavin
Kanellopoulos made a femto second laser flap and
injected 0.1 ml of 0.1% riboflavin in to the stroma and
used a 7w/cm2 UV A for 15 minutes. He has reported
favourable results
37. There is photo polymerization of the collagen fibers
Two types of reaction occurs when C3R is done. Aerobic
type 2 and anaerobic type 1.
The resultant reactive O2 species causes covalent bonds
between proteoglycans and collagen. This is seen as a
demarcation line at 300 – 350 microns depth.
If the epithelium is on availability of oxygen will be less.
38. It increases the diameter of the collagen fibrils
There is increase in the cohesiveness between collagen
fibrils and non collagen matrix
Increases the resistance to enzymatic digestion of the
collagenases
Apoptosis of unhealthy keratocytes
A decrease in the concentration of TGF beta is also seen
Most importantly it increases the corneal rigidity by up to
330%
39. Stabilization of progressive keratoconus
Induced corneal flattening. So myopia is reduced
Improvement in vision, both uncorrected and best
corrected
Reduction in higher order aberrations
Improvement in mean simulated keratometry
40. The flattening continues for up to 4 years
Eyes with advanced keratoconus show more flattening
during the first year
Increase in corneal hysteresis
41. In children the disease is aggressive and likely to
progress fast. Hence treatment should be started as
soon as possible.
There is an increased risk of infection, haze, scarring and
delayed healing in children
It must be remembered that good improvement is seen in
the age group 18- 39
42. Oxygen is needed for the photochemical reaction to
occur.
This may be the reason why higher intensities for a
shorter time and epi on treatments do not give
satisfactory results
Corneal thickness of at least 400micro meters is needed
for doing C3R. Otherwise the endothelium will be
affected
Iatrogenically hydrated and swollen cornea may not
respond similar to normal cornea. This may be because
of the increase in distance between the collagen fibers
43. Repopulation of the keratocytes takes several weeks.
This may cause scarring
Damage to corneal nerves
Delayed epithelial healing due to the above factors
Sterile infiltrates
Infection
Corneal haze
44. Following C3R many patients regain good vision with
spectacles.
Some who were intolerant to rigid lenses will be able to
wear rigid lenses with improvement in vision
Rose K lenses and semi scleral lens help patients who
are not improving with spectacles.
45. C3R combined with intrastromal corneal ring segments.
The rings will not reduce progression
Topography guided Photo Refractive Keratectomy along
with C3R will have the added advantage of reducing
irregular astigmatism
Phakic toric lens implantation can be done along with
C3R. But one must remember the fact that the
keratoconus may progress
46. Host keratocytes which replace the donor keratocytes
may produce abnormal collagen
The donor tissue may have been from undiagnosed
keratoconus eyes
Mechanical trauma following surgery like rubbing,
contact lens wear etc.