The document provides information about the Jackson Crossed-Cylinder (JCC) technique for determining astigmatism during eye exams. It discusses the optics and proper use of the JCC. It describes the historical origins of the JCC, how it works, and the step-by-step procedure for using it to refine the axis and power of astigmatic corrections. Common sources of error are also outlined. The JCC is presented as an important tool for optometrists to accurately measure and correct astigmatism in clinical practice.
Contact lens for congenital aphakia and other eye conditions for infants and toddlers. The slide presentation encompasses indications for CL fitting in paediatric, contact lens options, fitting techniques, challenges and contact lens as myopia control.
Detailed instumentaion and use of manual Lensometer and just a outline of automated lensometer.
I have used the picture of manual lensometer with out the parts describtion because i have explained orally by showing the picture..
Hope u all like it and may help you in learning better. :)
Contact lens for congenital aphakia and other eye conditions for infants and toddlers. The slide presentation encompasses indications for CL fitting in paediatric, contact lens options, fitting techniques, challenges and contact lens as myopia control.
Detailed instumentaion and use of manual Lensometer and just a outline of automated lensometer.
I have used the picture of manual lensometer with out the parts describtion because i have explained orally by showing the picture..
Hope u all like it and may help you in learning better. :)
This presentation covers the Optics & application of Jackson Cross Cylinder | Jackson Cross Cylinder works on an optical principle that constricts & expands the sturm's conoid.
This presentation covers the Optics & application of Jackson Cross Cylinder | Jackson Cross Cylinder works on an optical principle that constricts & expands the sturm's conoid.
T IS MAINLY TO REFINE THE AXIS AND POWER OF CYLINDER LENS AFTER COMPLETE SUBJECTIVE REFRACTION.
It is also used to identify to determine whether patient need cylinder power or not.
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.
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
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
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
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!
2. “....far more useful and far
more used” than any other
lenses in clinical refraction.
-Dr. Edward Jackson
JCC(Sharma IP)
3. Objective
To understand the optics and proper use of
Jackson Crossed-Cylinder in clinical practise.
JCC(Sharma IP)
4. Contents
1. Introduction to JCC
2. Historical Perspective
3. Optics – How is it made?
4. The choice of JCC
5. Detection of astigmatism
6. Refinement of axis
7. Refinement of power
8. Sources of Error
9. Points to ponder-Summary
10. Conclusion
11. Reference
JCC(Sharma IP)
5. Introduction to JCC
Jackson Crossed-Cylinder is a
combination of two cylinders of
equal strength but of opposite signs
placed with their axis at 90 degrees
to each other and mounted in a
handle.
Jackson Crossed-Cylinder (JCC)
technique is also called the flip-
cross technique.
JCC(Sharma IP)
6. Historical Perspective
1849-The original concept of crossed cylinders was
described by Stokes.
1855-The Stokes lens was used in a variation of the
present technique by Dennet
Crisp brought it to worldwide attention, and it has
become known as the JCC technique.
JCC(Sharma IP)
8. Optics- How is it made?
A typical JCC lens is a spherocylindrical lens having
a spherical power component combined with a cylinder
power component of twice the power of the sphere, and
of opposite sign.
Eg: +0.50 DS combined with -1.00 DC. This results in
a net power of +0.50 DC in one axis and -0.50 DC in
the other axis(+-50 DC).
+0.50/-1.00 @90
JCC(Sharma IP)
10. Contd...
Crossed cylinders of +0.25 DS combined with -0.50 DC
(+-25 DC) or +0.37 DS combined with -0.75 DC (to.37
DC), etc.,are available.
Thus, the two principal axes of a crossed-cylinder
lens exhibit equal cylinder power of opposite signs.
JCC(Sharma IP)
11. Marking of Principle meridian
The principal
meridians are marked
in the periphery of
JCC lens
In the UK, it is the
opposite.
JCC(Sharma IP)
White dots = axis of the plus
cylinder
Red dots = axis of the minus
cylinder
12. Handle of JCC
A handle is attached between the two marked axes, which
enables the lens to be "twirled" before the eye by rotation of
the handle.
In this manner, the positions of the minus and plus axes are
interchanged rapidly and alternately.
The common term used for the rotating the handle is known
as flipping.
Hence, the JCC is often termed as flip-cross cylinder.
JCC(Sharma IP)
13. Contd....
0.5 D Jackson cross-cylinder in
primary orientation. The handle
is down to the right and at 45º to
the horizontal. The label +.50 is
in the usual orientation for
reading; -.50 reads upward. The
markings are in red (as here) and
white (shown black here).
JCC(Sharma IP)
15. Choice of JCC
Vision 6/9 or better: use 0.25DC x-cyl
If results unreliable, then change up to 0.50 x-cyl. and see if
more reliable
Vision 6/12 or worse: use 0.50DC x-cyl
If results reliable and vision improves, change down to 0.25
Use a larger target until the vision improves!
Vision 6/24 or worse: try 0.75DC x-cyl
If results unreliable, use alternative method of astigmatic
correction (Astigmtic Fan, keratometry etc)
JCC(Sharma IP)
18. Starting point for JCC
After retinoscopy.....adjust sphere.
End point of spherical adjustment is the starting point
of JCC refinement.
Circle of least confusion must be on retina (ILM), so
check sphere first.
Remember Strums Conoid
JCC(Sharma IP)
19. Eg: Simple myopic astigmatism
Interval of Sturm
Circle of Least Confusion
Blur is due to combination of…
CLC in front of the retina
Focal lines being separated
“It’s very blurred”
20. With best spherical correction
Circle of Least Confusion
Has moved, is now on the retina
Interval of Sturm
Length unchanged
Reason the vision is still blurred
“That’s better but it still isn’t clear”
JCC(Sharma IP)
22. If astigmatism is present
But WHY
- because the correct axis can be found in the presence
of an incorrect power but the full cylindrical power
will not be found in the presence of an incorrect axis.
JCC(Sharma IP)
26. Example
You have performed retinoscopy on a patient
Retinoscopy value
-1.00DS/-1.00DCx180, 6/9
You have checked the sphere power
Now lets refine axis of the cyl.
JCC(Sharma IP)
29. Refining axis
Patient response
“Lens position 1 was clearer”
So, we rotate the cylinder lens towards the position of
the red markings
In this case, position 1
Initially, move by steps of about 15 deg, then use
smaller steps as we get closer
JCC(Sharma IP)
30. Patient response
We rotated the axis of the trial lens AND the handle of the x-
cyl by 20 deg
“Both lenses are equally blurred”
This means that the cyl axis of the trial frame now matches
the patient’s cyl axis
The true axis is 160 deg
In real life, you would continue until the patient sends us in
the other direction (reversal)
There is usually a range where the images appear equal, and we
need to find the limits
Choose the axis mid-way between the two reversals
JCC(Sharma IP)
31. “ They are same”
May be on axis, therefore move cyl axis by about 20deg and check to
see if it returns
May be within range of uncertainty (next slide)
0.25DC JCC may give insufficient difference
Try 0.50DC
0.50DC JCC may give too much distortion
Move down to 0.25DC
If none of the above help, use alternative technique.
JCC(Sharma IP)
32. Range of uncertainty
In real life, most patients will report that both lenses are equally
blurred over a range of axes
This is more common with low cyl power
You need to identify the range
Find where the patient tells you to rotate in the
opposite direction at each end
Select the axis in the middle of the range
JCC(Sharma IP)
33. How much axis to move?
Del Priore and Guyton
gave the guidelines
suggested in Table 20-2
for the initial change in
correcting axis position
relative to power of the
correcting cylinder while
checking the axis.
JCC(Sharma IP)
Source:William J Benjamin,2006, Borish’s Clinical Refraction, Butterworth Heineman Elsevier. 20: 818
35. Optical principle of power
refinement
When determining the power, JCC will either increase
or decrease residual cyl, either expanding or collapsing
the astigmatic interval and circle of least confusion
Thereby making the target less or more clear
JCC(Sharma IP)
36. Option 1 Circle of Least Confusion
Increases in size
Does not change position!
Interval of Sturm
Longer
“That looks awful”
JCC(Sharma IP)
37. Option 2 Circle of Least Confusion
Decreases in size
Does not change position!
Interval of Sturm
Shorter
“That is much better”
JCC(Sharma IP)
40. Example
Using ± 0.50 JCC
Retioscopy : -1.00DS/-0.75 DC X 120
If the patient prefers the lens
When red marks are aligned with trial cyl axis (120
deg),
add -0.50 DC
When white marks are aligned with trial cyl axis (120),
reduce -0.50DC
Equally clear: you have the right power
JCC(Sharma IP)
41. Contd.....
JCC(Sharma IP)
For each -0.50DC change, you need to add +0.25DS, to keep the circle of
least confusion on the retina
Add -0.25DS for each +0.50DC change
So in the example : -1.00DS/-0.75 DC X 120
If the patient prefers red marks
Final power is:
-0.75DS/ -1.25 DC X 120
44. Common errors
1.Not keeping the circle of least confusion on the retina
Starting with the wrong sphere power
Forgetting to change sphere power if cyl is changed by
0.50DC or more
2.Assuming the axis is correct if the patient says “they
look the same” without checking
Could be no astigmatism at all
Could be 90deg off
3.Incorrect presentation time – esp too quick
4.Poor alignment of JCC and trial frame axis
JCC(Sharma IP)
45. Points to ponder- Summary
JCC is always a sphero-cylindrical lens such that one meridian is plus
power and the other meridian is of equal minus power.
The red dots identify the axis of the minus power and the white dot
is of plus power.
While refining axis: JCC handle is parallel to trail lens cylinder axis
While refining power: JCC lens axis is parallel to trail lens cylinder
axis.
When patient says “ both sides are same” exclude all posibilities.
JCC(Sharma IP)
46. Conclusion
The most accepted procedure used by the
overwhelming majority of examiners is the JCC
technique.
Freeman and Purdum and Goar considered the JCC to
be the most delicate test for astigmatism.
The use of JCC is very important in clinical parctise of
refraction and an it serves as an important instrument
for optometrist.
JCC(Sharma IP)
47. Reference
1. William J Benjamin,2006, Borish’s Clinical Refraction, Butterworth Heineman
Elsevier. 20: 816-829
2. Wunsch SE. 1971. The cross cylinder. Int Ophthalmol Clin 11:131-153.
3.Brookman KE. 1993. The Jackson cross-cylinder: Historical perspective. JAm Optom
Assoc 64:329-331.
4. Crisp WHo 1943. Photographing cross cylinder tests. Am J Opht 26:758-760.
5. Duke Elder, 1998. Practise of Clinical Refraction, Butterworth Heineman Elsevier. 4:
181-183
6. Khurana AK 2013. Optics and refraction, 6: 133-134
7. Perlstein SII. 1982. Mounted cross-cylinder: A new mounted Jackson cross-
cylinder. Ann Opht/Ullmol 14:992.
8..Del Priore LV, Guyton DL. 1986. The Jackson cross cylinder, a reappraisal.
Ophthalmology 93: 1461-1465.
9. Sims CN, Durham DG. 1986. The Jackson cross-cylinder disproved. 'hans Am
Ophthailltol Soc 84:355-386.
JCC(Sharma IP)
The original concept of crossed cylinders was described by Stokes in 1849, who combined cylinders
of +4.00 DC and -4.00 DC so that they could be rotated in opposite directions, giving a variety of powers from
plano to a +4.00 OS sphere combined with -8.00 DC cylinder.
The Stokes lens was used in a variation of the present technique by Dennet in 1855.
However, the present technique was first promulgated and described by Jackson for the determination of cylinder power in 1887 and for axis in 1907.
The Jackson Crossed-Cylinder (JCC) lens in position before the phoropter's lens aperture, as would occur
during assessment of cylinder power of the right eye. The correcting minus cylinder in the phoropter is at
x180. A, The ICC axis of minus cylinder (red dots, Ilrrows) is aligned with that of the correcting cylinder lens.
B, The JCC lens has been flipped so as to reverse the positions of the JCC axes, and the JCC axis of plus
cylinder (white dots) is aligned with the axis of the correcting cylinder.
The original concept of crossed cylinders was described by Stokes in 1849, who combined cylinders
of +4.00 DC and -4.00 DC so that they could be rotated in opposite directions, giving a variety of powers from
plano to a +4.00 OS sphere combined with -8.00 DC cylinder.
The Stokes lens was used in a variation of the present technique by Dennet in 1855.
However, the present technique was first promulgated and described by Jackson for the determination of cylinder power in 1887 and for axis in 1907.