Artificial lenses implanted in the anterior or posterior chamber of the eye in the presence of the natural crystalline lens to correct refractive errors. Phakic IOLs an evolving technique in the field of refractive surgery for the correction of moderate to high refractive errors. Patients with high myopia (above -10 diopters) constitute only about 2% of the myopic population but 13-15% of patients presenting for refractive surgery belong to this group. The increased knowledge on anterior segment anatomy and availability of better imaging technologies along with improved IOL designs and surgical techniques have led to higher success rates with these lenses.
Compared to corneal refractive surgery , phakic IOLs compete favorably for the correction of high ametropias, with excellent predictability, efficacy, safety and quality of vision.
Th e use of premium IOLs requires more specifically than standard monofocal IOLs a thorough clinical and para clinical examination using modern equipments.
We will only mention micro-incision premium IOLs that are used
in our daily practice. All information regarding the characteristics of all available and especially multifocal IOLs are available in the SFO 2012 Report on presbyopia
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
2. Introduction
Artificial lenses implanted in the anterior or posterior
chamber of the eye in the presence of the natural
crystalline lens to correct refractive errors.
3. Phakic IOLs an evolving technique in the field of
refractive surgery for the correction of moderate to
high refractive errors.
Patients with high myopia (above -10 diopters)
constitute only about 2% of the myopic population but
13-15% of patients presenting for refractive surgery
belong to this group.
4. Lasik is justifiably still the most widely
practiced modality of refractive surgery
because of –
High level of comfort
Quick recovery
Stable predictable results
Ability to perform bilateral treatment in one sitting.
5. But when it comes to higher grades of
refractive error it has the following limitations:
Significant residual error.
Loss of best spectacle corrected visual acuity.
Risk of iatrogenic keratectasia when excessive ablation
done or residual bed is too thin.
Induction of tear film abnormalities.
Induction of higher order aberrations, which leads to poor
contrast sensitivity,
Limitation of night vision and diminished quality of vision.
6. Advantages of Phakic IOLS
in High Refractive Errors
Preservation of architecture of cornea
Predictable refractive results.
Preservation of accommodation
Predictable healing.
Rapid visual recovery.
Stable post-operative refraction.
7. Reversible and adjustable.
Cheap , no costly equipment like a lasik unit is
necessary.
The technique of implanting a phakic IOL is similar in
many ways to phacoemulsification and a good anterior
segment surgeon can easily incorporate it is his
practice.
9. Indication for Phakic IOLs
Any refractive error which is unsuitable for LVC could be
considered for phakic IOLs
Myopia beyond -12D
Hyperopia beyond +4D
Initial corneal thickness <480 microns.
Residual bed after LASIK is likely to be <280 microns.
10. History
1889
Clear lens extraction for the correction of myopia
Fukula in Austria/Germany : FUKULA SURGERY
Abandoned due to complications
1950s
Correcting myopia by inserting a concave lens into Phakic eye
1988
Baikoff : anterior chamber angle fixed IOL
Mid 1980s
Posterior chamber phakic IOLs : Fyodorov
1991
Artisan- Worst iris claw lens
11. Phakic IOL - Options
There are primarily three sites of fixation
ANTERIOR CHAMBER ANGLE – SUPPORTED
e.g BAIKOFF, NUVITA lenses
ANTERIOR CHAMBER IRIS – FIXATED
e.g VERISYSE
POSTERIOR CHAMBER IOLS
e.g STAAR ICL (Implantable Contact Lens) and PRL (Phakic Refractive
Lens)
ICL is more widely used.
12. Figure 3: Schematic representation of phakic IOL locations:
a. Angle supported. b. Iris clip. c. Posterior chamber shown in dotted
lines since it is covered by Iris.
13. Optical Advantages of
Phakic IOLs
Phakic IOLs are placed much closer to the nodal point
of the eye.
Hence, effective optic zone of phakic IOL is 1.25 times
on corneal surface.
14. Slight improvement in visual acuity in higher grades of
myopia - because reduction of minification effect
Since cornea is untouched quality of vision is better
after phakic IOL implants than LVC.
15. General criteria for implanting Phakic IOLs
Stable refraction (less than 0.5 D change for 6 months)
Clear crystalline lens
Ametropia not suitable/appropriate for excimer laser surgery
Unsatisfactory vision with/intolerance of contact lenses or spectacles
Anterior chamber depth greater or equal to
3.2 mm for Verisyse ( iris claw lens)* and angle supported PIOLs
^2.5 mm for posterior chamber PIOLs*
A minimum endothelial cell density of *
≥3500 cells/mm² at 21 years of age
≥2800 cells/mm² at 31 years of age
≥2200 cells/mm² at 41 years of age
≥2000 cells/mm² at 45 years of age or more
No ocular pathology ( corneal disorders, glaucoma, uveitis,
maculopathy, etc
* According to FDA
17. ADVANTAGES DISADVANTAGES
Potential to treat a large range of
myopic, hyperopic and astigamtic
refractive error.
Potential risk of an intraocular
procedure ( e.g endophthalmitis)
Allows the crystalline lens to retain its
function preserving accomodation.
Nonfoldable models require large
incision that may result in high
postoperative astigmatism
Excellent visual and refractive results
(induces less coma and spherical
aberration than LASIK)
Highly ametropic patients may require
additional photorefractive surgery (
Bioptics) for fine tuning the refractive
outcome.
18. ADVANTAGES DISADVANTAGES
Removable and exchangeable May cause irreversible damage (i.e
endothelial cell loss, cataract
formation, glaucomatous optic
neuropathy)
Frequently improves BSCVA in
myopic eyes by eliminating
minification effect of glasses
Implantation in hyperopic patients can
be followed by loss of BSCVA due to
loss of magnification effect of glasses.
Results are predictable and stable Other complications are common:
pupil ovalization, induced astigmatism,
chronic uveitis, pupillary block,
pigment dispersion.
19. Power Calculation for Phakic
IOLs
There are 3 parameters that are essential are-
Preoperative Spectacle power
AC Depth.
Horizontal and vertical radii of curvature of cornea.
20. Ancillary tests required
Unaided and best corrected VA
Anterior and posterior segment evaluation
White - to - white (w-w) measurement
High frequency (50 MHz) ultrasound biomicroscopy
Corneal endothelial cell count
22. Deciding the size
Anterior Chamber Angle Supported Phakic IOLs
Overall Length of IOL : 11.5 mm to 14.0 mm with 0.5
mm intervals.
W-W measurement ( with addition of 0.5 – 1.0 mm) –
most commonly used tools.
Others - Intraoperative AC sizer
Anterior segment OCT
23. Ac iris-fixated phakic IOLs
One size fits all length ( 8.5mm), sizing is not important
Sizing posterior chamber phakic IOLs
Sizing of the posterior chamber phakic IOLs is extremely
important – for getting appropriate vault
UBM and AS OCT – to measure sulcus-to-sulcus distance (
best tools to measure sulcus to sulcus distance)
w-w measurement plus 0.5 mm
24. Artemis high-frequency (50 MHz) 3D-digital ultrasound imaging of the
anterior segment. Red arrows indicate angle-to-angle distance; yellow
arrows indicate sulcus-to-sulcus distance.
26. Lowered vaulting to 20
degree
Thinned optic edge
Increased distance
from endothelium 0.6
mm
Baikoff ZB5M NuVita MA20
New rigid PMMA lens
Total diameter – 5mm
Real optic diameter
4.5mm
Edge decreased by
20%
27. Other models of angle
supported PIOLs
Two rigid PMMA devices:
ZSAL-4
Phakic 6
Three foldable hydrophilic acrylic IOLs:
Vivarte
I-CARE
Acrisof AC
One foldable “two parts” silicone/PMMA IOL:
Kelman-duet
30. Foldable hydrophilic acrylic angle-supported I-CARE lens (A and B).
Ultrasound biomicroscopy (UBM) showing the position of the haptic in the anterior
chamber angle (C).
31. Surgical Procedure
Topical pilocarpine
Topical or peribulbar anaesthesia
Incision
Cohesive viscoelastic
Lens is introduced, footplate is inserted in the
iridocorneal angle, second haptic is then placed, lens
is then rotated in place
Periphery iridectomy done
Incision is closed
32. Foldable “two parts” (Silicone optic/PMMA haptics) Kelman-Duet lens (A). The
haptics are implanted initially through a small incision (B), then the optic is
injected (C). The complex optic-haptics is assembled inside the anterior
chamber (D).
36. Have been largely given up because of complications
like progressive pupillary distortion and corneal
decompensation.
At present Alcon is conducting trials with an angle
fixated IOL which may become available for clinical
usage shortly.
38. IRIS-FIXATED PHAKIC IOL
Midperipheral fixation by a claw mechanism
Artisan/Verysise lens. Detail of the mid-peripheral iris
stroma enclavated by the haptic claw.
39. Iris-fixated Verisyse lens in situ.
Originally designed by Jan worst and named Lobster
claw lenses and subsequently renamed as
ARTISAN lenses and now marketed as VERISYSE.
40. Verisyse - Iris Clip Lenses
Made up of PMMA and have an overall diameter of
8.5mm.
In the power range -3D to -15.5D - available in 6mm
optic size
-15.5D to -23.50D and +1D to +12D – available in
5mm optic size.
Toric versions are also available now.
Artiflex – are foldable version with silicon optics and
PMMA haptics – ( introduced through a 3mm incision )
41. In september 2004, the FDA approved the first
phakic IOL..
The Verisyse(AMO/Optotec,USA Inc.) was approved for –
Myopia ranging from -5 to -20 D
Astigmatism </= to 2.5D
Adults 21 years of age or older
With anterior chamber depth( ACD) of 3.2 mm or
greater and Shaffer grade II as determined by
Gonioscopy.
45. Indications of Iris Claw lens
Treatment of refractive errors after penetrating
keratoplasty.
Treatment of Anisometropic Amblyopia in children.
Secondary implantation for Aphakia correction.
Treatment of refractive errors in patients with
keratoconus.
Correction of progressive high myopia in
pseudophakic children
Postoperative anisometropia in unilateral cataract
patients with bilateral high myopia
58. Posterior Chamber Phakic
IOL
Placed in the posterior chamber just in front of the
normal crystalline lenses.
Materials:
Silicone : PRL
Collamer : ICL
Hydrophilic acrylic : Sticklens
59. Properties desired in the IOL are:
Allow permeability of nutrients
Circulation of aqueous humor
Not cause crystalline lens or zonular trauma.
60. Implantable Collamer Lens (ICL)
In 1993, a posterior chamber phakic IOL made of
hydrophilic flexible material collamer, which is a
copolymer of HEMA (99%) and porcine collagen (1%),
was developed.
high
biocompatibil
ity and
permeability
to gas ,
metabolites
free space
left
between
the IOL
and the
crystalline
lens,
Avoid the
development
of cataracts.
61. Available in powers from -2D to -20D and +1D to +10D.
The toric version can correct upto 6D of astigmatism.
Extremely thin with optic centre measuring in thickness
about 50 microns and the haptics 500-600 microns.
Overall diameter varies between 11.5 to 13mm
Sizing depends on the white-to-white measurement.
62. In December 2005, second phakic IOL was
approved by FDA.
The Visian ICL ( Implantable Collamer Lens)
Approved for correction of –
Myopia ranging from -3 to -20 D
Astigmatism </= 2.5D
Adults 21- 45 years of age with ACD of 3.0 mm or
greater and Shaffer grade II as determined by
gonioscopy.
64. Silicone IOL
The PRL( Phakic Refractive Lens) is a hydrophobic
silicone single-piece plate design IOL with a refractive
index of 1.46
Mechanical touch, impermeability of nutrients, and
stagnation of aqueous flow without the elimination of
waste products cataract formation
Changes its vaulting to avoid this
65. Silicone IOL..cont..
The new models (PRL-100 and 101 (myopia), and
PRL-200 (hyperopia), which are claimed to float in the
posterior chamber with its haptics resting on the
zonules,
Decreased the incidence of cataract formation to
almost zero.
But complications, such as lens decentration and
zonular dehiscence with dislocation of the lens into the
vitreous cavity.
67. Procedure
Mydriasis
Topical or peribulbar anesthesia
Temporal clear corneal tunnel
Viscoelastic .
Foldable IOL insertion into AC (with an injector or with
forceps)
Check orientation
Placement of footplates below iris
Iridectomy
Closure of incision
68. A posterior chamber lens is folded
(A) and inserted through a small
incision (B) with a forceps.
69. Iridotomies
Both for iris clip and posterior chamber phakic IOLs
patent Iridotomies is an essential prerequisite.
Done either 1 week before the surgery with the yag
laser or
During surgery with scissors or using the vitrectomy
cutter.
70. Ideal sites for yag iridotomies prior to phakic IOL implant.
71. At the end of the procedure a peripheral iridectomy is
performed.
73. Glare and haloes
Incidence 2.4-54.3%.
The frequency of haloes
was higher when the ICL’s optical zone size was small.
The rate of haloes correlated to the difference between
the scotopic pupil diameter and the optical zone size.
74. Cataract
As a result of trauma to the crystalline lens during the
implantation procedure
Due to long-term contact between the IOL and the
crystalline lens.
Metabolic disturbances
The majority of these cases were anterior subcapsular.
Explantation of the ICL is easily
performed through the
same incision
75. Pigment Dispersion Syndrome
Rubbing at the optic–haptic junction on the posterior
face of the iris iris abrasion release of pigments
into the aqueous humor.
Pigment deposits had no visual consequences as they
were located at the optic–haptic junction rather than
the central optic.
76. If PC phakic IOL is:
Undersized decreased vaulting contact between
the IOL and the crystalline lens
Too large iris friction pigmentary dispersion
This is one important reason for adequately measuring
the sulcus-to-sulcus distance.
77. Pigmentary deposits are seen in the angle in an eye with a
posterior chamber phakic intraocular lens.
78. Decentration
Since the PRL lens floats in the posterior chamber
with the haptics resting on the zonular apparatus,
zonular erosion by the IOL haptics seems to be the
main mechanism for IOL instability and dislocation.
79. Bioptics
The combination of phakic IOL implantation followed by
LASIK in patients with extreme myopia or hypermetropia
and high levels of astigmatism.
When an anterior chamber phakic IOL is planned to be
combined with LASIK,
Corneal flap created just prior to the insertion of the lens;
then, at a later time, usually after 1month, the flap is lifted for
laser correction of the residual ametropia.
This two-step technique was called adjustable refractive
surgery (ARS) by Guell.
80. The rationale in performing the flap first is to avoid any
possibility of contact between the endothelium and
the IOL during the suction and cut for the LASIK
procedure.
81. Conclusion
The field of phakic IOLs has experienced tremendous
evolution in recent years.
The increased knowledge on anterior segment
anatomy and availability of better imaging technologies
along with improved IOL designs and surgical
techniques have led to higher success rates with these
lenses.
Compared to corneal refractive surgery , phakic IOLs
compete favorably for the correction of high
ametropias, with excellent predictability, efficacy, safety
and quality of vision.
In conventional cataract surgery the crystalline lens which measures
about 5 mm in the anterior posterior diameter is removed and we
have about 8 mm space, when the eye ball is filled up, between the
corneal endothelium and the posterior capsule to carry out all our
surgical maneuvers. In phakic IOLs since the normal crystalline
lens is retained there is only 3 mm space between the corneal
endothelium and the anterior capsule of the crystalline lens within
which all steps have to be carried out without damaging the corneal
endothelium, angle of the anterior chamber, iris, pupil and lens.
That is, a phakic IOL of 5mm optic size will have an effective optic zone of 6.25 mm on the corneal surface
of concave spectacle lenses being dispensed with.
These measures are sent to the manufacturer & they calculate the exact power of the Phakic IOL & dispense it.
Have been largely given up because of complications like progressive pupillary distortion, UGH Syndrome and corneal decompensation
Low molecular weight viscoclastics like HPMC is only recommended both for loading the lenses and during the surgical procedures.
