2. What is intraocular lens?
⢠An artificial lens implanted in the eyes
⢠Replaces the crystalline lens
⢠To correct the optical power of the eyes
following:-
Lens being
clouded by
cataract
Refractive surgery
3. Primary vs secondary implantation
⢠Primary implantation â use of IOLs during
surgery for cataract
⢠Secondary implantation â implantation of IOL
to correct aphakia in a previosly operated eye
4. Parts of an IOL
⢠OPTIC
Part of the lens that focuses
light on the retina.
⢠HAPTIC
Small filaments connected to
the optic that hold the lens in
place in the eye
HAPTEN
OPTIC
6. THE FIRST IOL!!
⢠PMMA made lens â 45 year
old female after performing
extracapsular cataract
extraction
⢠Disc shaped bi-convex design
⢠Site- posterior chamber
⢠First generation IOL
9. 4. Fourth generation IOLs
⢠Modern anterior chamber lens
⢠Flexible loops and multiple point fixation
⢠Advantages â more stable, better design, less
complications
⢠Disadvantages â anterior chamber is not the
physiological site for IOL
10. 5. Fifth generation IOLs
⢠PMMA lenses
⢠Foldable and small incision lenses
12. POSITIONING OF IOL
1. Posterior chamber
implantation
⢠Ciliary sulcus fixation
⢠In the bag fixation
⢠Scleral fixation
Eg:- modified C loop type
IOL
17. 3. Iris- fixated lens
⢠Fixed on the iris with
claws,loops or sutures
⢠Eg- Singh and Worstâs
iris claw lens
18. Different types of haptic angulation
relative to the plane of optic:-
For posterior chamber lens:-
⢠100 anterior angulation to keep the optic
part away from the pupil.
For anterior chamber lens:-
⢠Posteriorly angulated lens to vault the
intraocular lens away from the pupil
19.
20. FOCUSSING ABILITY OF IOLs
1. Unifocal intraocular lens
⢠Lens with unifocal power
⢠Can have problem with near vision
23. Special function IOLs
TORIC IOLs
⢠Correct any associated
astigmatism
ASPHERIC IOLs
⢠Reduce spherical
aberration
24. ANIRIDIA IOLs
⢠Cover the defects of aniridia or
partial iris loss as in trauma
⢠Has a black diaphragm over the
optic
PIGGYBACK IOLs
⢠An IOL piggybacking onto an
existing IOL or simultaneous
implantation of 2 IOLs
25. BLUE LIGHT FILTERING IOLs
⢠Lenses are yellow colored to screen out UV
Light and blue spectrum
⢠Reduced risk of age related macular
degeneration
PHOTOCHROMATIC IOLs
⢠UV absorbing photo chromes
26. IMPLANTABLE MINIATURE
TELESCOPE
⢠Miniature implantable Galilean
telescope
⢠Implanted in posterior chamber
⢠Contains number of micro lenses
in the optic which gives a
magnification of about 3 at the
central visual field
⢠Used to treat macular
degeneration
27. TELESCOPIC IOLs
⢠New generation miniature
telescopes which uses 2 mirrors
instead of lens to provide
magnification with minimum
loss of peripheral vision
28. Phakic IOLs
⢠IOLs used to correct myopia with the eyeâs
natural lens being untouched
⢠Implantable contact lenses
1. Angle supported lens
2. Iris â fixated lens
3. Sulcus supported lens
29. BIOMETRY
THEORETICAL FORMULAE
⢠Binkhorst formula
⢠Colenbranderâs formula
⢠Gull strandâs formula
⢠Hofferâs formula
EMPERICAL FORMULAE
⢠Modified Sanders-Retzlaff-Kraff formula
⢠SRK II
⢠SRK III
⢠SRK T
⢠Haigis formula
30. Binkhorst formula
⢠E= [N/(L-C)] â NK/(N-KC)]
E
⢠Emmetropic IOL power
L
⢠Axial length of the eye
K
⢠Corneal dioptric power
C
N
⢠Psuedophakic length of anterior chamber
⢠Refractive index of aqueous and vitreous humor
32. Modified SRK Formula
⢠E=A - 2.5L - 0.9K
⢠Parameters used in the formula are
estimated by
⢠A-scan ultrasonographic sonometry and
keratometry
⢠Instrument - biometer
34. ⢠Power ( I )required to produce Required post
operative refraction ( R ) ,
I = E â cr R
⢠cr â empirical constant
cr = 1 if E < 14
cr = 1.25 if E > 14
35. Complications of IOL implantation
⢠Mechanical damage to the IOL
⢠Dislocation
⢠Bullous keratopathy
⢠Posterior capsule rupture
⢠Anterior capsule opacification
⢠Posterior capsule opacification
⢠Calcium deposits within the optic of hydrophilic
intraocular lens
⢠Adherence
⢠UGH syndrome
⢠Sunset syndrome
37. âLens of the futureâ-liquid injectable
IOLs
⢠A new IOL concept that combines an acrylic
IOL with a liquid, injectable IOL may someday
allow patients to retain accommodation.
⢠Following IOL implantation, liquid IOL is injected
and capsular bag is inflated fully and IOL kept in
place
⢠Mechanism- forward movement and thickening
of lens