This document discusses age-related changes to the lens and grading of cataracts. It covers morphological, physiological, biophysical, biochemical, and crystallin changes that occur in the lens as part of the normal aging process. These changes can result in three main types of age-related cataracts: nuclear, cortical, and posterior subcapsular cataracts. The document also discusses other causes of cataract formation such as trauma, radiation, drugs, metabolism, and genetics.
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
Presbyopia/ Methods of Presbyopic Addition Determination (healthkura.com)Bikash Sapkota
DIRECT DOWNLOAD LINK ❤❤https://healthkura.com/presbyopia-near-addition/❤❤
Dear viewers Check Out my other piece of works at ❤❤❤ https://healthkura.com ❤❤❤
Presbyopia and techniques of measurement
A fantastic presentation in the topic "Presbyopia and techniques of measurement"
A detailed information about presbyopia, techniques of presbyopic add determination and different correction methods.
Informative slide presentation on presbyopia for ophthalmology residents, ophthalmologists, optometrists, ophthalmic assistants, ophthalmic technicians, ophthalmic nurses, medical students, medical professors, teaching guides.
Presentation Contents:
--Introduction to presbyopia
-Types of presbyopia
-Risk factors
-Symptoms and signs
-Refractive error and presbyopia
-Methods of determining near add.
-Management of presbyopia
In a nutshell..
- The evaluation and management of presbyopia are important because significant functional deficits can occur when the condition is left untreated
- Undercorrected or uncorrected presbyopia can cause significant visual disability and have a negative impact on the pt.'s quality of life
- Finally, every tentative addition should be adjusted according to the particular needs of the patient
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.
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
Presbyopia/ Methods of Presbyopic Addition Determination (healthkura.com)Bikash Sapkota
DIRECT DOWNLOAD LINK ❤❤https://healthkura.com/presbyopia-near-addition/❤❤
Dear viewers Check Out my other piece of works at ❤❤❤ https://healthkura.com ❤❤❤
Presbyopia and techniques of measurement
A fantastic presentation in the topic "Presbyopia and techniques of measurement"
A detailed information about presbyopia, techniques of presbyopic add determination and different correction methods.
Informative slide presentation on presbyopia for ophthalmology residents, ophthalmologists, optometrists, ophthalmic assistants, ophthalmic technicians, ophthalmic nurses, medical students, medical professors, teaching guides.
Presentation Contents:
--Introduction to presbyopia
-Types of presbyopia
-Risk factors
-Symptoms and signs
-Refractive error and presbyopia
-Methods of determining near add.
-Management of presbyopia
In a nutshell..
- The evaluation and management of presbyopia are important because significant functional deficits can occur when the condition is left untreated
- Undercorrected or uncorrected presbyopia can cause significant visual disability and have a negative impact on the pt.'s quality of life
- Finally, every tentative addition should be adjusted according to the particular needs of the patient
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.
Corneal metabolism
1. o Cornea requires energy for normal metabolic activities as well as for maintaining transparency and dehydration o Energy is generated by the breakdown of glucose in the form of ATP o Most actively metabolizing layer are epithelium and endothelium o Sources of nutrients : o Oxygen : mainly from atmosphere through tear film , with minor amount supplied by the aqueous and limbal vasculature o Glucose , amino acid, vitamins and other nutrients supplied to cornea by aqueous humor o Glucose also derived from glycogen stores in corneal epithelium o Epithelium consumes O2 10 times faster then stroma
2. o Three process or pathways – o Pentose shunt (Hexose monophosphate shunt) –occurs both in hypoxic and normoxic condition o Glycolysis (Embden meyerhof pathway) –anaerobic process , glucose / glycogen converted to pyruvate yeilding 2 ATPs o TCA or krebs or citric acid cycle- aerobic condition pyruvate is oxidized to yield 36 ATP, water, CO2.
3. o In normal conditions all the glucose consumed by the cornea o Glucose mostly come from aqueous humor o The rate of glucose consumption by the whole cornea is approx. 100 microgram/hr/cm2. o 1 mol. of glucose will be converted to the pyruvic acid and produced 2 molecules lactic acid and 2 mol. of ATP o In the krebs cycle, 1 mol. of glucose will utilize the pyruvic acid and O2 to produced 36 mol. ATP o Epithelium and endothelium will consume the oxygen
4. o The pentose phosphate pathway is used to metabolize five carbon sugars; one ATP and 2 NADH molecules are produced from oxidation of one glucose molecule o Produced intermediates for nucleic acid synthesis and some amino acids o This process will happen in hypoxic or normoxic condition o The purpose of glucose metabolism through the pentose shunt is the production of NADPH
The 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
Synoptophore is an instrument for diagnosing imbalance of eye muscles and treating them by orthoptic methods. In this presentation the parts of the synoptophore and the different slides used in the instrument are discussed
Corneal metabolism
1. o Cornea requires energy for normal metabolic activities as well as for maintaining transparency and dehydration o Energy is generated by the breakdown of glucose in the form of ATP o Most actively metabolizing layer are epithelium and endothelium o Sources of nutrients : o Oxygen : mainly from atmosphere through tear film , with minor amount supplied by the aqueous and limbal vasculature o Glucose , amino acid, vitamins and other nutrients supplied to cornea by aqueous humor o Glucose also derived from glycogen stores in corneal epithelium o Epithelium consumes O2 10 times faster then stroma
2. o Three process or pathways – o Pentose shunt (Hexose monophosphate shunt) –occurs both in hypoxic and normoxic condition o Glycolysis (Embden meyerhof pathway) –anaerobic process , glucose / glycogen converted to pyruvate yeilding 2 ATPs o TCA or krebs or citric acid cycle- aerobic condition pyruvate is oxidized to yield 36 ATP, water, CO2.
3. o In normal conditions all the glucose consumed by the cornea o Glucose mostly come from aqueous humor o The rate of glucose consumption by the whole cornea is approx. 100 microgram/hr/cm2. o 1 mol. of glucose will be converted to the pyruvic acid and produced 2 molecules lactic acid and 2 mol. of ATP o In the krebs cycle, 1 mol. of glucose will utilize the pyruvic acid and O2 to produced 36 mol. ATP o Epithelium and endothelium will consume the oxygen
4. o The pentose phosphate pathway is used to metabolize five carbon sugars; one ATP and 2 NADH molecules are produced from oxidation of one glucose molecule o Produced intermediates for nucleic acid synthesis and some amino acids o This process will happen in hypoxic or normoxic condition o The purpose of glucose metabolism through the pentose shunt is the production of NADPH
The 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
Synoptophore is an instrument for diagnosing imbalance of eye muscles and treating them by orthoptic methods. In this presentation the parts of the synoptophore and the different slides used in the instrument are discussed
PHYSIOLOGY OF AQUEOUS HUMOUR & IOP REGULATION 3.pptxAkashChaurewar1
This ppt is made available for free to use and modification.
This is made for presentation for PG seminar activity during MS ophthalmology residency 1st year by Dr Akash Chaurewar under guidance of Dr. Shubha Ghonsikar with mentors - Dr. Archana Vare and other faculty.
Discussion on Papillary carcinoma thyroid - category, types with definitions, other DD for pap ca thyroid along with a whole lot of beautiful cytology pictures - a feast to the eyes
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
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.
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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.
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!
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
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
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
1. AGE RELATED CHANGES OF
LENS AND GRADING OF
CATARACT
BIPIN BISTA
RESIDENT
OPHTHALMOLOGY
2. INTRODUCTION
• LENS SHOWS AGE RELATED CHANGES IN STRUCTURE, LIGHT TRANSMISSION,
METABOLIC CAPACITY & ENZYME ACTIVITY.
• LIGHT TRANSMISSION IS DECREASED D/T INCREASED BRUNESCENCE OF LENS
• LESS ELASTIC – DECREASE IN ACCOMMODATION – PRESBYOPIA
• METABOLIC ACTIVITY IS DECREASED
• DECREASE IN ANTI-OXIDANTS
• CHANGES IN CRYSTALLINS – AGGREGATION, DEGRADATION AND INCREASED
INSOLUBILITY.
3. MORPHOLOGY
• AFTER 2ND DECADE OF LIFE, THERE IS INCREASE IN MASS AND DIMENSION D/T
PROLIFERATION OF LENS EPITHELIAL CELLS AND DIFFERENTIATION INTO LENS
FIBER.
• WITH THE CONTINUOUS GROWTH OF EPITHELIAL CELLS AGE OF CELLS DECREASE
TOWARDS OUTER UNITS OF THIS REGION AS THE NEWEST ONE IS FOUND IN
PROGERMINATIVE ZONE AND OLDEST FIBERS ARE FOUND IN CENTER OF
NUCLEUS.
• EACH GROWTH SHELL REPRESENT A FIBER THAT ARE YOUNGER THAN PRECEDING
SHELL.
• WITH AGE, EPITHELIAL CELLS GETS FLATTEN WITH INCREASING BASAL SURFACE
AREA , THUS CELL COVERAGE FOR ANTERIOR CAPSULE LESSENS WHICH LEADS
4. MORPHOLOGY
• LENS FIBER SHOWS A TOTAL LOSS OR PARTIAL DEGENERATION OF NUMBER OF
PLASMA MEMBRANE AND CYTOSKELETAL PROTEINS WITH AGEING.
• SIGNIFICANT DEGRADATION IN MAJOR INTRINSIC PROTEIN -26, SPECTRIN,
VIMENTIN AND ACTIN
• CHOLESTEROL TO PHOSPHOLIPID RATIO IS DECREASED, WHICH LEADS TO
DECREASE IN MEMBRANE FLUIDITY AND PARTIALLY RESPONSIBLE FOR NUCLEAR
SCLEROSIS
• CHANGE IN PLASMA MEMBRANE AND CYTOSKELETAL MEMBRANE LEADS INCREASE
IN NUMBER OF FURROWED MEMBRANE AND MICROVILLI
• DEEPER CORTICAL FIBERS AND NUCLEUS AREN’T PRONE TO RUPTURES D/T
INCREASED CHOLESTEROL CONTENT.
6. PHYSIOLOGICAL CHANGES
• CHANGE IN CELLULAR JUNCTION AND ALTERATION IN CATION PERMEABILITY.
• MAJOR GAP JXN PROTEIN MIP26 LOSES IT’S A.A TO NEW VARIANTS.
• MEMBRANE POTENTIAL OF ISOLATED, PERFUSED LENS AT 20 YEARS IS -50MV BUT
AT 80 YEARS IT DECREASES TO -20MV.
• NA+ CONTENT INCREASES WITH AGE FROM 25 TO 40 MEQ/L, THUS, NA+ / K+
PERMEABILITY RATIO INCREASES APPROXIMATELY 6 TIMES WHICH WOULD LEAD
TO INCREASED OPTICAL DENSITY.
• IONIC CHANGE LEADS TO DECREASED MEMBRANE FLUIDITY ALSO RESULTS FROM
INHIBITION OF CA+ - ATPASE THUS LESSER CALCIUM ION IS PUMPED OUT.
7. BIOPHYSICAL CHANGES
• ABSORPTION OF BOTH UV RAYS AND VISIBLE LIGHT INCREASES WITH AGE.
• FREE AND BOUND AA ( TRYPTOPHAN, TYROSINE & PHENYL ALANINE),
FLUOROPHORES, YELLOW PIGMENTS AND SOME ENDOGENOUS COMPOUNDS
(RIBOFLAVIN) ARE RESPONSIBLE FOR ABSORPTION OF LENS.
• TRYPTOPHAN IS CLEAVED IN PRESENCE OF SUNLIGHT AND AIR TO FORM N-
FORMYL KYNURENINE AND METABOLIC PRODUCTS 3-HYDROXYL KYNURENINE
GLUCOSIDE (3-HKG)
• UV-A (315-400NM) AND 3-HKG ABSORBS BETWEEN (295-445 NM) AND
TRYPTOPHAN ABSORBS BETWEEN 295- 340 NM
8. BIOPHYSICAL CHANGES
• INCREASED CAPACITY OF LENS TO ABSORB LIGHT WITH INCREASED
SCATTERING PROPERTY OF LENS LEADS TO DECREASED TRANSPARENCY.
• NON ENZYMATIC GLYCATION OF PROTEIN BY MAILLARD REACTION LEADS TO
INCREASED FORMATION OF ADVANCED GLYCATION END PRODUCTS WHICH
INCREASES YELLOWING OF LENS.
• THIS REACTION IS INITIATED BY THE ATTACHMENT OF A SUGAR MOLECULE
(E.G., GLUCOSE) TO AN AMINO ACID, NORMALLY VALINE OR LYSINE. IN YOUNG
LENSES, 1.3% OF LYSINE RESIDUES OF HUMAN CRYSTALLINS (BOTH SOLUBLE
AND INSOLUBLE) ARE GLYCATED, BUT BY THE AGE OF 50 YEARS THIS
INCREASES TO 2.7% AND TO APPROXIMATELY 4.2% IN OLDER LENSES.
9. BIOCHEMICAL CHANGES
• OVERALL METABOLIC ACTIVITY DECREASES WITH AGE .
• LOSS OF PROTEIN FORMATION
• DECREASED GLUCOSE METABOLISM ( DECREASE IN GLYCERALDEHYDE-3-
PHOSPHATE DEHYDROGENASE, GLUCOSE-6-PHOSPHATE
DEHYDROGENASE,ALDOLASE,ENOLASE, PHOSPHOGLYCERYL KINASE &
PHOSPHOGLYCERATE MUTASE)
• DECREASE IN CATALASE AND SUPEROXIDE DISMUTASE , ACSCORBATE AND
GLUTATHIONE ( DECREASE IN GLUTATHIONE SYNTHEASE AND GAMMA GLUTAMYL
CYSTEINE SYNTHETHASE – DECREASE UPTAKE OF L-CYSTEINE)
• GLUTATHIONE PEROXIDES RESPONSIBLE FOR LIPID PEROXIDES AND HYDROGEN
PEROXIDE BREAKDOWN DECREASES ( REDUCED FORM >> OXIDISED FORM).
10. CRYSTALLINS
• ACCUMULATION OF HIGH–MOLECULAR-WEIGHT (HMW) AGGREGATES
• PARTIAL DEGRADATION OF POLYPEPTIDES
• INCREASED INSOLUBILITY
• PHOTO-OXIDATION OF TRYPTOPHAN AND THE PRODUCTION OF
PHOTOSENSITIZERS
• LOSS OF SULFHYDRYL GROUPS
• NONENZYMATIC GLYCATION
• DEAMIDATION OF GLUTAMINE AND ASPARAGINE RESIDUES
• RACEMIZATION OF ASPARTIC ACID RESIDUES
These changes
can alter the
short-range
spatial order of
the crystallins
and therefore
decrease
transparency
11. CRYSTALLINS
• POST-TRANSLATIONAL MODIFICATION : INTRAMOLECULAR DISULPHIDE BOND
WITHIN ALPHA A-CRYSTALLINS, GLYCATION OF LYSINE RESIDUES, CROSS –
LINKING ,DEAMIDATION OF A ALPHA CRYSTALLINE AND GAMMA S CRYSTALLINE
AND LOSS OF C-TERMINAL END OF A ALPHA CRYSTALLINE LEADS TO
DECREASE ACTIVITY OF CHAPERONE PROTEIN.
• DECREASE SOLUBILITY D/T OXIDATION OF SULFHYDRYL GROUP : LEADS TO
DISULPHIDE FORMATION
• INCREASE IN GLYCATION OF CRYSTALLINS IN PRESENCE OF GLUCOSE OR
ASCORBIC ACID RESULTS IN CROSS-LINKING AND FORMATION OF HMW.
12. CRYSTALLINS
• DEAMIDATION OF ASPARAGINASE RESIDUES CAN ALTER THE STRUCTURE ;
DISTABILISE THE PROTEIN AND INCREASE ITS SUSCEPTIBILITY TO
PROTEOLYTIC DEGRADATION.
• RACEMISATION OF ASPARTYL RESIDUE : CONVERSION OF THE L-ISOMER
(NORMAL FORM) INTO THE D-ISOMER
14. NUCLEAR CATARACT
• CAUSES CENTRAL OPACITY
• GREATER AMOUNT OF SCATTERING OF LIGHT AND
YELLOWING
• BILATERAL, ASSYMMETRIC
• POOR COLOR DISCRIMINATION
• MONOCULAR DIPLOPIA
• SLOWLY PROGRESSIVE
• GREATER VISUAL IMPAIRMENT (DISTANT>NEAR)
• LENTICULAR MYOPIA D/T INCREASED R.I
• SECOND SIGHT : IN PATIENTS WITH MYOPIC SHIFT, THEY
WILL BE ABLE TO READ WITHOUT GLASSES
• BRUNESCENT CATARACT
15.
16. CORTICAL CATARACT
• ASSOCIATED WITH LOCAL DISRUPTION OF
MATURE LENS FIBER STRUCTURE.
• WITH THE LOSS OF ESSENTIAL
METABOLITES, EXCESSIVE PROTEIN
OXIDATION AND PRECIPITATION
• PROGRESSION VARIES
• C/O GLARE
• HISTOLOGICALLY – LOCAL SWELLING &
DISRUPTION OF LENS FIBERS CELLS &
GLOBULES OF EOSINOPHIL – MORGAGNIAN
GLOBULES.
17. CORTICAL CATARACT
• VACUOLES AND WATER CLEFT
• SEPARATION OF LAMELLAE BY THE CLEFTS
• WEDGE SHAPED OPACITY AT THE
PERIPHERY AND CENTRAL SHARP POINTED
OPACITY IN CENTER – CUNEIFORM /
CORTICAL SPOKES.
• WHITE OPACITY ON SLIT-LAMP AND DARK
SHADOWS ON RETROILLUMINATION
• WEDGE SHAPED OPACITY SPREADS ALONG
THE ADJACENT FIBERS
• INTUMESCENT CATARACT
20. POSTERIOR SUBCAPSULAR CATARACT
• SEEN IN YOUNGER AGE THAN NUCLEAR
AND CORTICAL CATARACT
• PRESENT IN POSTERIOR CAPSULE
• LOCATED AXIALLY
• INCREASED DIMINUTION OF VISION
(NEAR>FAR) OBSCURES MORE LIGHT IN
PUPILLARY APERTURE
• GLARE
• ALSO OCCURS AS A RESULT OF
CORTICOSTEROID, ALCOHOL USE, TRAUMA
TO IONIZING RADIATION.
21. POSTERIOR SUBCAPSULAR CATARACT
• HISTOLOGICALLY, OCCURS BY POSTERIOR MIGRATION EPITHELIAL CELL
MATTER, LEADING TO SWELLING AT POSTERIOR AXIS WHICH ARE CALLED
WEDL OR BLADDER CELLS.
22. DRUG INDUCED LENS CHANGES
• CORTICOSTEROIDS : LONG TERM USE MAY CAUSE PSC. RELATED TO DOSE
AND DURATION
• INTRA-OCULAR USE FOR RETINAL NEOVASCULARISATION AND INFLAMMATION
HAS HIGHEST INCIDENCE OF PSC AND STEROID INDUCED OCULAR
HYPERTENSION
24. MIOTICS
• ECHOTHIOPHATE IODIDE >> PILOCARPINE
• SEEN IN PATIENTS WITH LONGER THERAPY
• SMALL VACULOES
• PROGRESSION TO POSTERIOR CORTICAL AND NUCLEAR REGION
25. AMIODARONE
• STELLATE PIGMENT DEPOSITION IN ANTERIOR CORTICAL AXIS
• ALSO DEPOSITED IN CORNEAL EPITHELIUM AND CAUSES OPTIC
NEUROPATHIES
27. TRAUMA
• CONTUSION
VOSSIUS RING : RING OF PIGMENT FROM THE PUPILLARY RUFF TO BE IMPRINTED ON ANTERIOR
SURFACE
TRAUMATIC CATARACT : INVOLVE ONLY A PORTION OR ENTIRE LENS, INITIALLY THERE IS STELLATE
OR ROSETTE SHAPED CATARACT USUALLY AXIAL IN LOCATION
DISLOCATION AND SUBLUXATION : EQUATORIAL EXPANSION FOLLOWING COMPRESSION WHICH
DISRUPT ZONULAR FIBERS . COULD BE ANTERIOR OR POSTERIOR. PHACO/IRIDO DONESIS, HIGH
ASTIGMATISM, MONOCULAR DIPLOPIA.
• PERFORATING AND PENETRATING INJURY : OPACIFICATION OF CORTEX AT THE SITE
• IOFB
• RADIATION
28.
29.
30.
31. RADIATION INDUCED CATARACT
• IONISING RADIATION : EXTREMELY SENSITIVE, MORE THAN 20 YEARS,
YOUNGER ARE MORE SUSCEPTIBLE , PUNCTATE OPACITY WITHIN THE
CAPSULE, FEATHERY ANTERIOR SUBCAPSULAR OPACITY THAT RADIATE TO
EQUATOR. X-RAY -0.001 TO 10 NM WAVELENGTH
• INFRARED RADIATION : GLASS BLOWER CATARACT , PEELING OFF OF THE
ANTERIOR CAPSULAR LAYER, ASSOCIATED WITH CORTICAL CATARACT
• UV RADIATION : CORTICAL CATARACT IN EXPOSURE TO SUNLIGHT.
• MICROWAVE RADIATION : LESS LIKELY IN HUMANS, ANTERIOR/POSTERIOR
SUBCAPSULAR CATARACT.
32. CHEMICAL INJURY
• ALKALI IS POTENT TO CAUSE CATARACT IN ADDITION TO DAMAGE TO CORNEA
AND CONJUNCTIVA
• INCREASES PH AND DECREASES AQUEOUS GLUCOSE AND ASCORBATE
• ACID ARE LESS LIKELY TO CAUSE CATARACT.
33. METALLOSIS
• SIDEROSIS BULBI : IRON IOFB,
EPITHELIUM AND CORTICAL FIBER :
YELLOWISH TINGE INTO RUSTY
BROWN DISCOLORATION
• CHALCOSIS : COPPER CONTAINING FB
DEPOSITS IN DM, ANTERIOR LENS
CAPSULE OR OTHER BM, RESULTING
IN SUNFLOWER CATARACT – PETAL
SHAPED DEPOSITION OF WELLOW OR
BROWN PIGMENT IN LENS CAPSULE
THAT RADIATES FROM ANTERIOR POLE
TO THE EQUATOR.
34. ELECTRICAL INJURY
• PROTEIN COAGULATION AND
CATARACT FORMATION
• MORE LIKELY IF THERE IS HEAD
TRANSMISSION
• INITIALLY, LENS VACUOLES ARE SEEN
IN ANTERIOR MID PERIPHERY AND
LATER ON LINEAR SUBCAPSULAR
OPACITIES
• MAY REGRESS, REMAIN STATIONARY
OR MAY LEAD TO COMPLETE
CATARACT.
35. METABOLIC CATARACT: DIABETES MELLITUS
• AFFECTS LENS CLARITY AS WELL AS R.I AND ACCOMMODATIVE AMPLITUDE OF LENS.
• ACUTE MYOPIC SHIFTS
• BILATERAL WIDESPREAD SUBCAPSULAR LENS
• MULTIPLE GREY WHITE OPACITIES THAT HAVE A SNOWFLAKE APPEARANCE : SUPERFICIAL
ANTERIOR AND POSTERIOR CORTEX.
• CLEFTS AND VACUOLES ARE FORMED
• UNEASY TO DIFFERENTIATE
• ACCUMULATION OF SORBITOL AND ACCOMPANYING CHANGES IN HYDRATION, INCREASED
NON-ENZYMATIC GLYCATION OF LENS PROTEIN AND INCREASED OXIDATIVE STRESS
37. GALACTOSEMIA
• INHERITED AR DISORDER
• INABILITY TO CONVERT GALACTOSE TO GLUCOSE
• INCREASED CONVERSION INTO GALACTITOL
• DEFECT IN 1 OF 3 ENZYMES : GALACTOSE-1-PHOSPHATE URIDYLTRANSFERASE,
GALACTOKINASE, UDPGALACTOSE-4 EPIMERASE
• CLASSIC GALACTOSEMIA : GAL-1-PUT
• SYMPTOMS : MALNUTRITION, JAUNDICE, HEPATOMEGALY MENTAL DEFICIENCY (1ST WEEK OF
LIFE)
• FATAL IF UNTREATED
• “OIL DROPLET APPEARANCE ON RETROILLUMINATION
38. HYPOCALCEMIA
• IDIOPATHIC, D/T UNINTENDED DESTRUCTION OF PARATHYROID GLAND DURING
THYROID SURGERY
• PUNCTATE IRIDESCENT OPACITY IN ANTERIOR AND POSTERIOR CORTEX
• MAY BE STABLE OR PRODUCE SERIOUS COMPLICATION
39. WILSON DISEASE
• HEPATOLENTICULAR DEGENERATION
• SUNFLOWER CATARACT : REDDISH BROWN PIGMENT ON THE ANTERIOR
CAPSULE, SUBCAPSULAR CORTEX IN A STELLATE SHAPE.
40. MYOTONIC DYSTROPHY
• AD
• DELAYED RELAXATION OF CONTRACTED MUSCLES, PTOSIS, WEAKNESS OF
FACIAL STRUCTURE, CARDIAC CONDUCTION DEFECTS, PROMINENT FRONTAL
BALDING
• POLYCHROMATIC IRIDESCENT CRYSTAL MADE UP OF WHORLS OF
PLASMALEMMA FROM THE LENS FIBER.
• THESE CRYSTALS ARE SEEN IN CASES OF CHOLERSTEROL CRYSTAL
DEPOSITION AS WELL.
41. EFFECTS OF NUTRITION, ALCOHOL AND
SMOKING
• SEVERAL EPISODE OF DIARRHOEA
• ASSOCIATION OF VITAMIN A,C & E
• SMOKERS WITH HIGH LEVEL OF BETA CAROTENE HAVE INCREASED RISK OF
LUNG CANCER
• LUTEIN (SPINACH, KALE AND BROCCOLI) AND ZEAXANTHINE : CAROTENOIDS
FOUND IN LENS
• SMOKER AND ALCOHOLIC HAVE INCREASE RISK OF NUCLEAR OPACITY AND
MACULAR DEGENERATION.
42. POSTVITRECTOMY CATARACT
• TREATMENT INDUCED CATARACT
• USUALLY RESOLVES
• DEVELOPS CATARACT WITHIN TWO YEARS POST-OPERATIVELY
• ASSOCIATED WITH INCREASED OXYGEN TENSION
43. CATARACT AND HYPERBARIC OXYGEN
THERAPY
• FRANK NUCLEAR CATARACT
• RESOLVES AFTER CESSATION OF THERAPY
44. CATARACT AND ATOPIC DERMATITIS
• OCCURS IN 2ND TO 3RD DECADE
• UPTO 25% CASES
• USUALLY BILATERAL
• ANTERIOR SUBCAPSULAR OPACITY : SHIELDLIKE OPACITY