2. Introduction `
â˘Artificial lenses implanted in the anterior or posterior
chamber of the eye in the presence of the natural crystalline
lens to correct high degree of refractive error.
4. History
⌠Barraquer and Strampelli in the middle of the 20th century used an anterior chamber design
1950s
⌠correcting myopia by inserting a concave lens into the phakic eye
1988
⌠Baikoff : anterior chamber angle-fixed IOL
Mid 1980s
⌠Posterior chamber phakic IOLs : Fyodorov
1991
⌠Artisan-Worst iris claw lens
5. Angle -supported Baikoff ZB5M (left) and the NuVita MA20 (right).
Peripheral
contact
points are
arcuate
shaped
And
footplates
broader
9. Ideal Candidate
â˘Age > 21years.
â˘Stable refraction (less than 0.5D change for 1 year)
â˘Clear crystalline lens
â˘When initial corneal thickness is < 480Îź.
â˘Unsatisfactory vision with/intolerance of contact lenses or spectacles
â˘Anterior chamber depth greater than or equal to
⌠3.2mm for the iris-claw lens and angle-supported PIOLs
⌠2.5mm for posterior chamber PIOLs
10. â˘A minimum endothelial cell density of
⌠âĽ3500 cells/mm2 at 21years of age
⌠âĽ2800 cells/mm2 at 31years of age
⌠âĽ2200 cells/mm2 at 41years of age
⌠âĽ2000 cells/mm2 at 45years of age or more
â˘No ocular pathology ( glaucoma, uveitis, maculopathy, etc.)
â˘Stable keratoconus
â˘Post PK.
11. INVESTIGATIONS
oUnaided and best corrected VA
oAnterior and Posterior segment evaluation
oWhite-to-white (w-w) measurement
oHigh-frequency (50MHz) ultrasound biomicroscopy/AS-OCT
oCorneal endothelial cell count
12. Fig. 11.9 Pupil diameter
measurement using infrared
technologies (P2000, Procyon):
10 pictures in a 2-s sequence
13. IOL Power Calculation
â˘
ACIOL
Patients refraction
Keratometry
ACD
PCIOL
Patients spectacle refraction
Corneal power
ACD ,angle to angle distance
VAN DER HEJDE formula BINKHORST formula
14. IOL power calculation
ďśACD and angle-to-angle distance are best-obtained using optical coherence tomography (OCT),
but can also be measured using ultrasound biomicroscopy (UBM) or Scheimpflug imaging.
ďśACD is measured from the corneal apex to the anterior surface of the crystalline lens, and is
use to calculate effective lens position (ELP) in PCIOLs by substracting the distance between the
pIOL and the crystalline lens from the ACD. The ELP is typically 0.8mm in the Artisan/Verisyse
lens.
ďśWhite-to-white (WTW) measurement with an IOL-Master or calipers can be used to estimate
angle-to-angle distance.
ďśCorneal power is calculated using keratometry or topography to measure the curvature of the
cornea.
17. Angle Supported ACIOL
RIGID pIOLs SPECIFICATIONS REFRACTIVE CORRECTION
Phakic 6 IOL Rigid PMMA
Heparin coated
-2.0D to -25D
+2.0D to +10 D
ZSAL-4 Rigid PMMA -6.0 D to -20D
FOLDABLE pIOLs
Vivarte One piece IOL- Acrylate -7.0 to -22 D
Kelman Duet Two piece
Optic â SILICONE
Haptic - PMMA (tripod)
-8.0D to -20D
Acrysof One piece - acrylate
Icare (Corneal) One piece- acrylate -5D to -20D
18. A. Phakic 6 (Ophthalmic Innovations International).
b ACRIOL (Soleko).
c Vivarte (Ciba).
d Kelman Duet (Tekia).
e Acrysof (Alcon)
19. c. Foldable I-Care (Corneal)
. A. Rigid ZSLA-4 (Morcher)
. B. Foldable AcrySof (Alcon).
20. Foldable âtwo partsâ (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).
21. Procedure
ďTopical pilocarpine
ďtopical or peribulbar anesthesia
ďIncision
ďcohesive viscoelastic
ďlens is introduced , footplate is inserted in
the iridocorneal angle, second haptic is then
placed, lens is then rotated in place
ďperipheral iridectomy
ďincision is closed
24. Iris fixated pIOL
Rigid IOLs
Artisan/Verisyse IOL PMMA
Flexible lobster claws
FDA approved
-1.0D to -23.5D
+3D to +12 D
Foldable IOLs
Artiflex IOL Foldable optical â silicone
Rigid haptic - PMMA
-2D to -14.5 D
25. . a Rigid Artisan pIOL (Ophtec). b Foldable Artiflex pIOL (Ophthec)
26. Indications of Iris Claw lens
ďTreatment of refractive errors after penetrating
keratoplasty.
ďTreatment of refractive errors in patients with
keratoconus.
ďCorrection of progressive high myopia in
pseudophakic children, and
ďpostoperative anisometropia in unilateral cataract
patients with bilateral high myopia
29. Surgery
A corneal or scleral incision is made along with two paracentesis for lens
manipulation.
OVD is injected into the AC followed by the pIOL, which is then fixated into the
iris using an enclavation needle to hold the iris and an implantation forceps to
depress the claw into the iris. Centration of the lens over the pupil is essential,
and mild ovalization after the surgery is not uncommon due to the effect of the
miotic agent.
Intraoperative peripheral iridectomy (Vannas scissors) or
two preoperative neodymium:YAG (Nd:YAG) laser iridotomy 2 weeks before
should be done to prevent pupillary block.
The incision is large enough to require 10-0 nylon sutures.
40. PCIOLs
specifications
Fyodorov PCIOL Silicone haptic IOL
Adatomed IOL( Chiron)
STAAR ICL Foldable ,one piece ,collamer
PRL ( Phakic refractive lens) foldable one-piece plate haptic pIOL ,
hydrophobic silicone
correction
ICL model V4; â3 to â23
D),
hyperopia (ICL model V3;
+3 to +22 D),
a toric myopic model
with implemented
cylinder (addition of
cylinder +1 to +6 D)
PRL models 100 and 101;
â3 to â20 D) and
hyperopia (PRL model
200; +3 to +15 D).
41. INDICATIONS of Phakic TICL
ďś correction of moderate to high myopia in patients with thin corneas.
ďśHyperopia
ďśHigh myopic astigmatism
ďśStable keratoconus
ďśPost radial keratotomy
ďśPost penetrating keratoplasty.
43. Implantable Collamer Lens
ďIn 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
biocompatibi
lity and
permeability
to gas ,
metabolites
free space
left
between
the IOL and
the
crystalline
lens,
Avoid the
development
of cataracts.
44. Procedure
ďMydriasis
ďTopical or peribulbar anesthesia
ďtemporal clear corneal tunnel
ďViscoelastic
ďFoldable IOL insertion into AC (with an injector or
with forceps)
ďCheck orientation
ďPlacement of footplates below iris
ďIridotomy
ďClosure of incision
45. A posterior chamber lens is folded
(A) and inserted through a small
incision (B) with a forceps.
47. Advantages Of Phakic IOL
ď Allows the crystalline lens to retain its function
ďPredictable outcome
ďImmediately stable,as refractive outcome is independent of healing process
ďExcelllent vision even in dim light
ďReversible
ďEasily adjustable with complimentary corneal surgeries.
ďLess damage to cornea compared to LASIK.
48. DISADVANTAGES
ď patient has to go through intraocular surgery
ďPostop astigmatism
ďGlare and haloes
ďAngle closure glaucoma.
ďProgressive endothelial loss
ďChronic uveal inflammation
ďLens displacement/decentration
ďCataract (subcapsular)
ďPigment dispersion .
49. Bioptics
ďThe combination of phakic IOL implantation followed by LASIK
in patients with extreme myopia or hypermetropia and high levels of
astigmatism.
ďWhen an anterior chamber phakic IOL is planned to be combined
with LASIK, the corneal flap can be 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.
ďThe 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.
50.
51. Foldable pIOLS â 3mm incision is only required.
Rigid IOLs â 5 to 6mm incision
Scleral incisions â less astigmatism
Length and distance to limbus(corneal incision) â increases the postop astigmatism.
52. Postop Astigmatism
ďą The incision size and location as one parameter for choosing
the appropriate phakic IOL.
ďąFor patients with preexisting astigmatism of less than 0.75 D,
foldable pIOLs are an advantage.
ďąCorneal astigmatism between 1 and 2 D may be reduced by a
larger incision (5-6mm) on the steep corneal meridian and thus
rigid pIOLs can be implanted.
ďąEven larger values of preexisting astigmatism should be
treated with toric pIOLs or a combination with other refractive
procedures.(LASIK)