Aphakia

1. APHAKIA
D R . A N K I TA M A H A PAT R A

2. INTRODUCTION
• Aphakia means absence of crystalline lens from the eye.
• Optically Aphakia means absence of lens from pupillary area and it does not takes part
in refraction
Absence of crystalline lens from patellar
fossa

3. CAUSES :
1. congenital
2. surgical
3.Traumatic extrusion
of lens
4. Posterior
dislocation of lens in
vitreous

4. OPTICS OF APHAKIA
1. CHANGES IN CARDINAL DATA OF EYE
2. IMAGE FORMATION IN APHAKIC EYE
3. VISUAL ACUITY IN APHAKIA
4. ACCOMODATION IN APHAKIA
5. BINOCULAR VISION AND APHAKIA

5. CHANGES IN CARDINAL
DATA
• Eye becomes highly HM
• Power reduces from +60 to +44D
• Anterior focal point becomes 23.2
mm in front of cornea
• Posterior focal 31 mm behind the
cornea
• Two principle points are almost on
anterior surface of cornea
• Nodal points are nearer to each
other and 7.75mm behind cornea

6. Average image magnification reported by different methods
of aphakia correction
Spectacle : 33%
Contact lens : 10%
ACIOL : 2-5%
PCIOL : 0 %( about)
IMAGE FORMATION IN APHAKIC EYE

7. Large image falsifies the VA recorded on the
Snellen’s chart
VA recorded theoretically better than the actual
VA in terms of visual angle
A vision of 6/9 with corrected aphakic eye
should be equivalent to 6/12 of an
emmetropic eye because of high magnification
of spectacle (33%)
VISUAL ACUITY IN APHAKIA

8. Due to absence or loss of lens from
its position accommodation become
zero
ACCOMODATION IN APHAKIA :

9. • Presence of aniseikonia is detrimental to the
development of BSV ( < 5% aniseikonia )
• In uniocular aphakic child , the major hindrance to
development of BSV is aniseikonia of 30% due to
anisometropia, develop suppression amblyopia.
• Unilateral aphakic if corrected with spectacle , usually
develop annoying diplopia
• As soon as possible operation of another eye in
bilateral cataract.
• IOLS claim to offer no barrier to fusion since the image
size of the pseudophakic eye is same as that of phakic
emmetropic eye.
BINOCULAR SINGLE VISISON AND APHAKIA

10. OPTICAL DEFECT IN APHAKIA
Acquired high hypermetropia
Against the rule astigmatism
Absence of accommodation
Change in colour vision

11. CLINICAL FEATURES
• SYMPTOMS :
Marked defective vision for far and near.
Erythropsia and cynopsia i.e., seeing red and blue Images due
to excessive entry of ultraviolet and infrared rays in the
absence of crystalline lens.

12.  Limbal scar - Surgical Aphakia.
 Anterior chamber deeper than normal.
 Iridodonesis.
 Jet black pupil.
 Purkinje image test: 3rd and 4th images are
absent.
 Fundus examination: small hypermetropic
disc.
 Retinoscopy shows high HM
SIGNS :

13. TREATMENT
SPECTACLE
CONTACT LENS
IOL
REFRACTIVE CORNEAL
PROCEDURE

14. SPECTACLE
• Optical principle is to correct the error by convex lens of
appropriate power.

15. Predictingthe power of anaphakic lens
• Laurance suggested the power of spectaclelens
Faphakic=+11.00 D+(1/2)Fpre-aphakic
• Retzlaff and karffdescribed formula of predictingaphakic
refraction
Faphakia = 80.4 – 1.65 L-0.7 K
• Where ,L=axial length of eye , K=preoprative keratometry
finding in diopters

17. 1. Increased retinal imagesize
2. Decreasedfield of view
3. Presenceof ringscotoma, Jack-in-the-box-phenomenon
4. Spherical aberrations
5. Motion of object in field of view
6. Cosmetic blemishes
7. Increased ocular rotations
8. Cumbersome to use
9. Problem of near vision
DISADVANTAGES

18. • If correcting lens is placed at anterior focal point of the eye, size of retinal
image directly proportional to the anterior focal length and inversely
proportional to the refracting power of the eye.
• Retinal image size( aphakia/emmetropia)
(23.23/17.05) =(58.64/43.05) =1.36
• Or increased in retinal image sizeof36%
• In unilateral aphakia corrected with spectaclesBSVimpossible due to high
magnification
1. INCREASED RETINAL IMAGE SIZE

19. • In B/L aphakia greatly increased image sizemeansthat
aphakic patients must adapt to new size-distancerelationship
Familiar object not only appear to be much
larger , they also appear to be
muchcloser
Initially , patient is visually
uncoordinated, he/she Pours water on
the table instead of glass until eventually
after Some months of trial and error , a
new coordination of
Hand and eye develops.

20. • Sometimes aphakic patients achieve central visual acuity
that exceeds the best VA obtained before surgery due to
magnification of retinal imagesize.
• Increased magnification may permit the prescribing
of weaker reading addition.

21. 2. DECREASED FIELD OF VIEW
50 degree all around
Both monocular and binocular vision restricted

22. Based on prismatic effect of strong plus lens causes angular
gap in object space completely around the lens which is
know as ring scotoma
3.RING SCOTOMA
center to the ring scotoma wearer has corrected vision
Ring scotoma of about 15 degree extending from 50-65 degree from central fixat

23. • Ring scotoma moves in opposite direction ofthe
eye movement( rovingeyescotoma)
• Ringscotoma creates different problems
especially from 2- 10 feet ,which is generally in
ordinaryroom
Factorseffect onsizeandpositionof ring scotoma
1. Lenspower
2. Vertex distance
3. Lenssize
4. Pupil size
5. Lensthickness
6. Basecurve
Exceptvertexdistanceand pupilsizeall other show
direct relation with sizeof ringscotoma

24. • Object seems to jump in and out of field of view asit moves
out of and into the ring scotoma
• Simply sudden disappearance and sharp reappearance of the
object in visual spacewith ringscotoma
JACK-IN-THE-BOX-PHENOMENON :

26. Magnification of image is more at
the periphery of the lens due to
prism effect
Objects appear stretched out(large
,nearer,elongated in radial
direction) at the corners like a pin-
cushion.
• Moving objects appear to be
faster
• Straight lines become curves
4.PIN CUSHION DISTORTION

28. 5. MOTION OF OBJECT IN FIELD OF VIEW
In high plus error , when the eyes are steady and head moved
towards an object then marked reversed motion (against
motion) of the field ofview is experienced
• This is due to prismatic effect( base in ) in the direction
of head movement
• This motion often referred to as swim
• swim can be avoided by moving the eyes from one
fixation point to another while the head stationary but
this may produce distortion
• Best procedure is to turn head slowly so thathead and eye
moves slowly

29. • Angle of eye turning in changing fixation from one object
point to another increases in comparison to
emmetropic.
7. INCREASED OCULAR ROTATION

30. CONTACT LENS
• ADVANTAGES
• Less magnification of
image
• No chromatic aberrations
• No prismatic affect
• Wider field of vision
• Cosmetically acceptable
• Better for uniocular
DISADVANTAGES
• More cost
• Cumbersome to wear-both for
young and old age
• FB sensation
• Corneal complications may be
associated

31. • It is treatment of choice who are unsuitable for IOL
implantation or who have experienced afailed IOL
implants
• Common in unilateral aphakia
• Contact lens provide less image magnification (about
5-7%) which make possibility of BSVin uniocular
aphakia

32. • 6-10 weeks post surgical to permit healing/ settling of power
• Find any contraindication for CLfit
• Spectacle Refraction
• Measurement of Oculardimension
– Keratometry
– Pupil size, shape, position
– Eyelids integrity
– CLfitting
• Over refraction (astigmatism / near addition)
• BSV
– After care
GENERAL PROCEDURE

33.  RGPlenses: caseswith high corneal astigmatism and corneal distortion
 Hydrogellenses: caseswith low astigmatism or failedRGPlens wearers
 Siliconeelastomer : caseswith low astigmatism and pediatric aphakic
patients
 Sclerallenses: patients with significant cornealdistortion
 Tinted lenses:to attenuate bright light and offersome UV protection
CONTACT LENS OPTIONS IN APHAKIA

34. ADVANTAGES
Little image magnification
No spherical and
prismatic aberration
Minimum or no
aniseikonia
Normal peripheral field
Cosmetically well
accepted
DISADVANTAGES
Risks and complications may be more
Infections
Dislocation of IOL ( child rubbing eye)
Posterior capsular opacities
It needs specially qualified surgeons and
sophisticated instrument.
The cost is more
IOL

35. IOL
IOLimplantation in cataract ,has goodoutcome
IOL implantation in children provides the benefit of reducing dependency
on compliance in comparison with other external optical devices.
Disadvantages are technical difficulties of implanting an IOL in eyes of
children, selecting an appropriate IOL power, and the risk of PCO.
Both IOLs and aphakic contact lenses may provide similar visual acuity
(VA) after surgery for unilateral cataract in the presence of good
compliance
In unilateral cases,primary implantation is indicated assoon asthe patient is fit
for anesthesia, ideally between 2 and 3 months of age.

36. AGE (YRs) RESIDUAL REFRACTION
2-4 +5D
4-5 +4D
5-6 +3D
6-7 +2D
7-8 +1.5D
8-10 +1D
10-14 +0.5D
>14 PLANO
IOL POWER CONSIDERATION FOR MYOPIC SHIFT

37. 1.PARENTAL COUNSELLING :
a. Post op care
b. Treatment of amblyopia
c. Frequent follow ups for changing refraction
d. Chances of PCO, glaucoma, squint and management
2. SITE OF IOL IMPLANTATION :
Capsular support a. adequate – in the bag
b. compromised – Capsular tension ring or sulcus fixation
3. PEDIATRIC CAPSULORHEXIS :
Hard to perform due to high capsule elasticity and tension

38. 4. SECONDARY IOL IMPLANTATION :
If adequate peripheral capsular support is present, the IOL
is placed into the reopened capsular bag or in the ciliary
sulcus.
Most commonly used IOL for secondary implantation is
the three piece AcrySof Intraocular Lenses.
Anterior chamber IOLs and scleral or iris-
posterior chamber IOLs are used in children
when other viable options are lacking.

41. • Refractive corneal surgery is under trial forcorrection of aphakia .
It includes
1.KERATOPHAKIA : Lenticule prepared from donor
cornea is placed between the lamella of patient’s
cornea.
REFRACTIVE CORNEAL PROCEDURE

42. 2.EPIKERATOPHAKIA :
A lenticule prepared from donor cornea is
stitched over the surface of patient’s cornea after
removing epithelium.
3.LASIK

43. THANK YOU