
The lens is absent from the pupillary area
 Congenital absence
 Dislocation into the vitreous
 Extruded outside the eye
 Surgically removed
 Absorption of the lens matter

Changes in the cardinal data of the eye

Image formation in the aphakic eye

Visual acuity in aphakia

Accommodation in aphakia

Binocular vision in aphakia
Eye is highly
hypermetropic
 Power is reduced to
44D (60D)
 Anterior focal point is
23.2 mm in front of
cornea
(17.2mm)Posterior
focal point is 31mm
behind cornea
(24.4mm)

Principal points are at
the anterior surface of
cornea ( 1.5mm
behind)
 Nodal points are 7.75
mm behind anterior
surface of cornea
(7.2mm)


Image size in aphakia corrected with
spectacles is 30% magnified

Image size in aphakia corrected with contact
lens is magnified by 4.5 to 5%

Visual acuity of spectacle corrected eye is
recorded better than actual visual acuity in
terms of visual angles

Total loss of accommodation

Bifocal or progressive spectacles

Multifocal IOLs

Monocular aphakia corrected with spectacles
will result in aniseikonia

Can be corrected with IOL or Contact lens





Operative scar at limbus
Deep AC
Iridodonesis
Jet black pupil
Absent Purkinje images
(3,4)

Associated
abnormalities


High hyperopia
Fundus exam -small disc

Spectacle

Contact lens

Intra-ocular lens

Refractive corneal surgery
Total dioptric power = +58 D
Refractive state = Emmetropia
7/29/2017
Cornea= +42 D
Lens= +16 D
Total dioptric power = +42 D
Cornea= +42 D
Refractive state = High Hypermetropia
7/29/2017
Lens= +0 D
A high power (thick) convex lens is required to correct vision
7/29/2017
•
•
+10 D lens with correction of associated
astigmatism ( usually ATR )
Add + 3 D for near vision ( Total +13D )
Advantages
•
•
•
Cheap
Easy
safe

Many disadvantages
 Heavy glasses
 Poor cosmetic appearance
7/29/2017
7/29/2017

Many disadvantages
 Magnification of 30% - unilateral aphakia, assess
distance
• Spectacle magnification=
Corrected image size
Uncorrected image size
Anterior focal distance in ametropia
Anterior focal distance in emmetropia
23.2 = 1.36 = 30 % magnification
17.05
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False depth perception
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False depth perception
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False depth perception
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False depth perception
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False depth perception
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False depth perception
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False depth perception
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
Many disadvantages
 Restricted field of vision
 Roving ring scotoma
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Ring scotoma-
?
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Ring scotoma-
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Ring scotoma-
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Roving Ring scotoma-
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Jack in the box-
 Spherical aberrations – pincushion defect
7/29/2017
 Spherical aberrations – pincushion defect
 Coloured vision
 Separate glasses for near
Total dioptric power = +58 D
Refractive state = Emmetropia
7/29/2017
Cornea= +42 D
Lens= +16 D
Total dioptric power = +42 D
Cornea= +42 D
Refractive state = High Hypermetropia
7/29/2017
Lens= +0 D
CONTACT LENS
7/29/2017
•
•
•
+13 D contact lens
For near vision – spectacle correction is needed ( Add +3D )
Advantages–
–
–
–
–
•
Less magnification
Less prismatic distortions
Better field of vision
Better cosmetically
Better for uniocular aphakia
Disadvantages-
– Requires good maintenance
– Cost
– cumbersome
•
•
Lens is placed inside the eye
Positions and power
– ACIOL- +17D
– Iris fixated- +18D
– PCIOL- +20 D
•
Advantages
– Good optics
– Permanent
•
Disadvantages– Surgical procedure - complications

Parts
Optic
Haptic

Material
PMMA
Silicone
Hydrogel

Keratophakia

Epikeratophakia

Hyperopic Lasik - Can correct small amounts
of hyperopia up to 4 D