This presentation discusses the process of fitting soft contact lenses. It begins with defining soft contact lenses and outlining the objectives of understanding fitting steps and assessment. Baseline measurements are taken, including HVID, keratometry, and refraction. Trial lenses are selected based on these measurements. Fitting is then assessed based on criteria like movement, centration, and comfort response. Ideal fits show full corneal coverage and clear vision. Modifications may be made by altering the base curve, diameter, or thickness if needed. The proper fitting of contact lenses is important to ensure comfort and good vision.
SOFT CONTACT LENS FITTING
1. Alternative names of soft contact lens.
2. Need to know fitting requirement and performance requirements.
3. Centration and decentration of soft contact lens. -- There are cartesian system and binasal system.
4. what governs fitting of lens.
5. There are need to know about physical properties of soft contact lens.
6. Now, what is sag and sagital depth.
7. Finally, SAME SAG AND SAME DIAMETER but DIFFERENT DESIGN AND DIFFERENT BEHAVIOUR.
8. Parameters of soft contact lens -
total diameter
back optic zone radius
centre thickness
front optic zone radius
water content
9. There are two types of prescribing methods -
empirical prescribing
trial fit prescribing
10. Effect of a blink with soft contact lens - too flat and too steep.
11. Requirements of lens movement.
12. Lens lag position - primary gaze, up gaze and lateral gaze position.
13. Compulsory of lower lid push up test.
14. Ranges of fitting of soft contact lens - either too fit or too loose or ideal fitting.
15. All step of soft contact lens fitting is done.
Scleral lens is a large rigid contact lens with a diameter range of 15mm to 25mm. Its resting point is beyond the
corneal borders, and are believed to be among the best vision correction options for irregular corneas. Wearing scleral lens also can postpone or even prevent surgical intervention as well as decrease the risk of corneal scarring.
SOFT CONTACT LENS FITTING
1. Alternative names of soft contact lens.
2. Need to know fitting requirement and performance requirements.
3. Centration and decentration of soft contact lens. -- There are cartesian system and binasal system.
4. what governs fitting of lens.
5. There are need to know about physical properties of soft contact lens.
6. Now, what is sag and sagital depth.
7. Finally, SAME SAG AND SAME DIAMETER but DIFFERENT DESIGN AND DIFFERENT BEHAVIOUR.
8. Parameters of soft contact lens -
total diameter
back optic zone radius
centre thickness
front optic zone radius
water content
9. There are two types of prescribing methods -
empirical prescribing
trial fit prescribing
10. Effect of a blink with soft contact lens - too flat and too steep.
11. Requirements of lens movement.
12. Lens lag position - primary gaze, up gaze and lateral gaze position.
13. Compulsory of lower lid push up test.
14. Ranges of fitting of soft contact lens - either too fit or too loose or ideal fitting.
15. All step of soft contact lens fitting is done.
Scleral lens is a large rigid contact lens with a diameter range of 15mm to 25mm. Its resting point is beyond the
corneal borders, and are believed to be among the best vision correction options for irregular corneas. Wearing scleral lens also can postpone or even prevent surgical intervention as well as decrease the risk of corneal scarring.
Troubleshooting bifocals and Market Availability in Nepal
Bifocals in Anisometropia
Prismatic Effect in Bifocal
Bifocal Prescription
Bifocals in High Astigmatism
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
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
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.
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
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
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
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!
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
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.
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.
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
1. UNIVERSITY OF GONDAR
COLLEGE OF MEDICINE AND HEALTH SCIENCE
COMPREHENSIVE SPECIALISED HOSPITAL
DEPARTMENT OF OPTOMETRY
Presentation on soft contact lens fitting procedure and assessment
Prepared by; Getenet Shumet (BSc, MSc student)
Moderator; Haile woretaw (MSc,F-LVPEI,Ass’t prof)
Gondar, Ethiopia
July, 2021
3. OBJECTIVES
At the end of this presentation we will able to;
Define soft contact lens
Describe the types of soft contact lens fitting
List factors affecting soft contact lens fitting
List and describe each steps of soft contact lens fitting
Describe the soft contact lens fitting assessment
List steps of soft contact lens insertion and removal
3
4. Introduction
Soft contact lens is a type of contact lens made of soft, flexible
plastics that allow oxygen to pass through to the cornea
Are made of a flexible hydrophilic or modern silicone- hydrogel
material
Easier to adjust and are more comfortable than RGP lenses
4
5. Cont…
Have a wide spherical and toric power range
Soft contact lenses continue to dominate most contact lens
markets
The first lens is fit empirically
Fitting procedure and assessment is depend on the lens type
There are different ways of fitting assessment of soft contact
lens
5
6. Soft contact lens fitting
Contact lens fitting can be:
Empirical fitting: without use of any trial lens
Diagnostic fitting: use of trial lens
6
7. Factors which affect lens fit
Manufacturing method
Water content
K- readings
Modulus of elasticity
Lid tonus
Tear film
7
8. Fitting steps
Complete process of SCL fitting can be divided in to three
segments:
A. Baseline measurement
B. Trial lens parameter
C. Fitting assessment
8
10. A. Baseline measurement
Initial eye examination-SLE and history
To identify any pathology in the eye
Mainly anterior segment structures
10
11. Horizontal visible iris diameter (HVID)
Important to identify the total diameter of SCL
Normal value: range:10-14mm
average: 11.6mm
Available methods are:
normal mm scale
Slit lamp
Corneal topography
Vernier scale
11
12. Palpebral fissure height(PFH)
Higher PFH patients are suggested for large diameter contact
lens and vice versa
Available methods are:
normal mm scale
Slit lamp
Corneal topography
Vernier scale
12
13. Pupil size
Important to identify optical zone of SCL
In contact lens practice it is measured in dim light condition
Optical zone= pupil size + 2mm
Available methods are:
normal mm scale
Corneal topography
Vernier scale
13
15. B. Trial lens parameter
Base curve
Total diameter
Power
15
16. Base curve
It is the radius of curvature of back surface of the contact lens
Should be 0.6 to 1.0 mm flatter than average K reading
Formula: B.C = 337.5/D
D= dioptric power of average K
BC for SCL’s are specified as:
-Steep (8.0mm to 8.3mm)
-Medium (8.4mm to 8.6mm)
-Flat (8.7mm to 9.0mm)
16
17. Total diameter (TD)
Is the width of the contact lens from edge to edge
Should be 2mm greater than HVID
Total diameter (TD) =HVID + 2mm
17
18. Contact lens power
Obtained from refraction
vertex distance for more than ±4D
Formula : BVPcl =Fsp/1-(dFsp)
where : BVPcl =back vertex power of contact lens in diopter
Fsp = spectacle power in diopter
d =vertex distance in meter
18
19. C. Fitting assessment
Contact lens fitting can be :
optimal fit/ normal fit
steep fit/ tight fit
flat fit/ loose fit
19
20. Evaluation of Fit
Patients comfort response
Fairly comfortable -probably good fit
Uncomfortable -predicts loose fit(excess movement)
Very comfortable -May be steep or tight (immobile)
20
21. Corneal coverage
Slit lamp, diffuse illumination
Eye in primary position, lens should show full corneal
coverage about 1 to 2mm beyond limbus
Recording: complete or partial
Full coverage (1 -2mm) – Ideal
Greater than 2 mm – lens too large
Corneal exposure – lens too small
21
22. Lens centration
Is the superimposition of center of cornea and center of
contact lens
Equally centered in all distance beyond limbus in all directions
Centered in all position – ideal
Centered – steep fit
decentered with corneal exposure in any position of gaze-
flat/ loose fit
22
23. Movement
Movement is required due to :
Removes and disperses ocular debris
Promotes tear exchange
Patient asked to look straight in primary gaze and asked to
blink normally
Estimated in diffuse light and moderate to high magnification
with blink
0.2mm – 0.4 mm ---- ideal
Less than 0.2 mm …..steep fit
Greater than 1.0 mm …flat fit
23
24. Push up test
Patients looks straight and examiner pushes the lens up
vertically through the pressure of lid
Easy displacement- smooth recovery – ideal fit
Resistance to displacement – may not re center – tight fit
Easy displacement- quick recovery – Loose fit
24
25. Lens Lag
Is the resistance of the lens to move with the eye to any gaze
from its primary position
Patient asked to look up and lens move down slightly –Lag
1mm to 1.5 mm – Ideal
Little or no – steep fit
Greater than 2 mm-flat fit
25
26. Edge Alignment
Edge of the lens is observed with reference to the conjunctiva
If the edge is sliding smoothly and aligning with conjunctiva
is the ideal
If indent on cornea- tight or steep
If it stands off - loose
26
27. Other responses
Vision before and After blink
If vision will remain same and clear- ideal fit
If vision clears with blink – steep fit
If vision gets blur with blink- flat fit
Keratometry: Clarity of mires is observed
27
29. Soft toric lenses Fitting assessment
Is same as soft spherical contact lenses except lens rotation
Reference marks:
Different reference laser marks imprinted on the toric lenses
But it does not indicate the axis/meridian of astigmatism
Location of laser marks varies from company to company
Based on laser marks, rotation of lens is assessed
29
31. Rotation :
When we insert a lens in the eye there may be the following
situations
Same position during the blink and after the blink
Displace during the blink but may retain its location after the
blink
It may not be in the same position it moves because of blink
effect
If it rotates, the axis may rotate
so we add or subtract the amount of rotation to the axis of the
prescription
31
32. Cont...
LARS Rule:
This is used to assess the rotation of lens and prescribe correct
axis with markings at 6 o'clock position
First, estimate the degree of lens rotation
If the lens moves towards left add the degree of mislocation to
the Rx axis
If the lens moves towards right subtract the degree of
mislocation to the Rx axis
32
33. Cont…
The CAAS mnemonic is useful for lenses with markings at
3 & 9 o’clock:
Rotation CLOCKWISE = ADD, Rotation ANTICLOCKWISE
= SUBTRACT
33
36. Modifications for fittings
Alter the lens if ideal fit is not achieved by changing;
Base curve
Diameter
Thickness
Rule of thumb- 0.3mm change in the base curve = 0.5 mm
change in Diameter.
36
37. Cont…
Correcting a Flat fit
Tighten/decrease the base
curve, but keep the diameter
the same
Increase the diameter and
keep the base curve the
same
• Always recheck the
modification with a trial lens
Correcting a Steep fit
Loosen/increase the base
curve, but keep the diameter
the same
Decrease the diameter and
keep the base curve the
same
37
38. Over refraction
Refraction over trial lens
Algebraically add power
Note- additional power needed should be less than 4D
If cyl required –fit toric
It the VA is not as clear as expected do over refraction
38
39. Signs and symptoms of steep fit
Fluctuating VA, clears after each blink (Little or no movement
up on each blink)
Comfortable at first, then not
Circumcorneal injection ,and indentation
Conjunctival drag
Keratometry mires distorted, then clear after each blink
Air bubbles centrally, over pupil
39
40. Signs and symptoms of flat fit
VA unstable with each blink
Patient awareness of the lens
Too much movement with each blink
Lens may be falls out
Air bubble under the lens, especially on the periphery of the
lens
“K” mires are blurred after each blink
40
43. SUMMARY
Proper fitting of the contact lens is important
Consider the base curve, diameter and lens power for fitting
Make modifications of fitting if necessary
An ideally fitting:
Comfort
Crisp, clear and stable vision
Full corneal coverage in all gaze positions
Regular edge alignment to conjunctiva
Smooth recovery from push-up
Adequate movement for tear exchange 0.2 – 0.4mm
Explain insertion and removal, care and handling and cleaning
to the patient!!!
43
44. REFERENCES
Young G. Evaluation of soft contact lens fitting characteristics. Optometry
and vision science. 1996;73(4):247-54.
Morgan PB, et al. International contact lens prescribing in 2019. Contact
Lens Spectrum
The ABCs of Fitting Soft Contact Lenses
Juniper publisher
Essential Contact Lens Practice
Fitting assessment of various contact lenses: Optometry Zone
Smart optometry videos on soft contact lens fitting
44
The first lens is fit empirically; often the lens chosen is one that the manufacturer reports "will fit 80% of patients
Soft contact lenses continue to dominate most contact lens markets, accounting for about 90 percent of all fits worldwide
Rotation : When we insert a lens in the eye there may be two situations, It may be in the same position during the blink and after the the blink. It may displace during the blink but may retain its location after the blink. It may not be in the same position it moves because of blink effect. If it rotates, the axis may rotate, So to avoid this cylinder in unwanted axis we add or subtract the amount of rotation to the axis of the prescription so that the axis of the cylinder coincides with the axis of the eye.