Aetiology of Cataract

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PROBLEMS OF APHAKIA IOL

• Maj
• M. Ahsan Mukhtar
• FCPS, FRCS (Glasg)
• CLASSIFIED EYE SPECIALIST
• REGISTRAR VITREO-RETINAL SURGERY

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OBJECTIVES

• Enlist common problems of aphkaia
• Briefly describe the mechanism / physics of these
  problems
• Know basics of intraocular lenses

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PROBLEMS OF APHAKIA

• Relative spectacle magnification (RSM)
• Anisometropia in unilateral aphakia
• Aberrations
• Heavy lenses (glasses)
• Visual field limitation
• Loss of ultra-violet protection
• Other problems
• Cystoid Macular edema
• Retinal Detachment
• Increase In Proliferative Diabetic Retinopathy
• Amblyopia in children with unilateral aphakia

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PROBLEMS OF APHAKIA

• Relative spectacle magnification (RSM)
• Anisometropia in unilateral aphakia
• Aberrations
• Heavy lenses (glasses)
• Visual field limitation
• Loss of ultra-violet protection
• Other problems
• Cystoid Macular edema
• Retinal Detachment
• Increase In Proliferative Diabetic Retinopathy
• Amblyopia in children with unilateral aphakia

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RELATIVE SPECTACLE MAGNIFICATION

• The ratio between the corrected and uncorrected
  image size
• Image is 33 larger in corrected aphakia
• Patient may misjudge distances
• Actual VA of an Aphakic reading 6/9 is approx
  6/12

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RELATIVE MAGNIFICATION AND IMAGE SIZE

• SOLUTION
• Intra-ocular lens
• Contact lens
• Isiekonic lens
• Corneal procedures

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PROBLEMS OF APHAKIA

• Relative spectacle magnification (RSM)
• Anisometropia in unilateral aphakia
• Aberrations
• Heavy lenses (glasses)
• Visual field limitation
• Loss of ultra-violet protection
• Other problems
• Cystoid Macular edema
• Retinal Detachment
• Increase In Proliferative Diabetic Retinopathy
• Amblyopia in children with unilateral aphakia

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ABERRATIONS

• IMAGE DISTORTION
• troublesome to the newly aphakic patients
• Straight lines appears curved except when viewed
  through a very small axial zone of lens

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ABERRATIONS
RING SCOTOMA The prismatic power of the more
peripheral parts of a spherical lens
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ABERRATIONS

• JACK-IN-THE-BOX
• The direction of the scotoma changes as the
  patient moves his eyes, and objects may appear
  out of the scotoma or disappear into it.
• SOLUTION
• Tell the patient to move his head instead of
  moving eyes while wearing aphakic glasses

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PROBLEMS OF APHAKIA

• Relative spectacle magnification (RSM)
• Anisometropia in unilateral aphakia
• Aberrations
• Heavy lenses (glasses)
• Visual field limitation
• Loss of ultra-violet protection
• Other problems
• Cystoid Macular edema
• Retinal Detachment
• Increase In Proliferative Diabetic Retinopathy
• Amblyopia in children with unilateral aphakia

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HEAVY GLASS LENSES

• Use plastic lenses

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PROBLEMS OF APHAKIA

• Relative spectacle magnification (RSM)
• Anisometropia in unilateral aphakia
• Aberrations
• Heavy lenses (glasses)
• Visual field limitation
• Loss of ultra-violet protection
• Other problems
• Cystoid Macular edema
• Retinal Detachment
• Increase In Proliferative Diabetic Retinopathy
• Amblyopia in children with unilateral aphakia

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VISUAL FIELD LIMITATION

• SOLUTION
• Ask Patient to move head instead of moving eyes
  while wearing aphakic glasses

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PROBLEMS OF APHAKIA

• Relative spectacle magnification (RSM)
• Anisometropia in unilateral aphakia
• Aberrations
• Heavy lenses (glasses)
• Visual field limitation
• Loss of ultra-violet protection
• Other problems
• Cystoid Macular edema
• Retinal Detachment
• Increase In Proliferative Diabetic Retinopathy
• Amblyopia in children with unilateral aphakia

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LOSS OF ULTRA-VIOLET PROTECTION

• SOLUTION
• Intra-ocular lens with UV protection
• Glasses with UV protection

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PROBLEMS OF APHAKIA

• Relative spectacle magnification (RSM)
• Anisometropia in unilateral aphakia
• Aberrations
• Heavy lenses (glasses)
• Visual field limitation
• Loss of ultra-violet protection
• Other problems
• Cystoid Macular edema
• Retinal Detachment
• Increase In Proliferative Diabetic Retinopathy
• Amblyopia in children with unilateral aphakia

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OTHER PROBLEMS DUE TO APHAKIA

• Cystoid Macular edema
• Retinal Detachment
• Increase In Proliferative Diabetic Retinopathy
• Amblyopia in children with unilateral aphakia
• Occlusion therapy
• IOL
• Contact lenses

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INTRA OCULAR LENSES
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INTRA OCULAR LENSES

• The optic (the central refracting element)
• The heptics

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IOL MATERIAL

• Optic
• Polymethylmethacrylate (PMMA)
• Silicon
• Acrylic (hydrophillic and hydrophobic)
• Hydrogel
• Heptics
• Polypropylene (3 piece)
• Same material as optics (1 piece)

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IOL DESIGN
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TYPES OF IOL
AC IOL
Iris claw Lens
PC IOL
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IOL TYPES

• Monofocal IOL
• Multifocal IOL
• Toric
• Accomodative

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PLACEMENT OF IOL IN EYE

• The posterior chamber (PC IOL)
• capsular bag
• Sulcus
• The anterior chamber (AC IOL)
• Iris / pupil supported
• Angle supported

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AC-IOL

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PC IOL

• PC IOL in Capsular bag

• PC IOL

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RIGID VS FOLDABLE IOLS

• Rigid
• PMMA
• One piece to facilitate maximal stability and
  fixation
• Foldable
• Silicone IOLs have lower rates of posterior
  capsular opacification than PMMA IOLs
• Acrylic IOLs
• Hydrogel IOLs have higher water content
• Collamer IOLs are a mixture of collagen and
  hydrogel (newly developed)

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ADVANTAGES OF IOLs

• All problems of aphakia ------ gone
• Broader field of view
• Lesser problem of image magnification
• Binocularity is maintained

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DISADVANTAGES OF IOLS

• Problems of accommodation
• Chances of dislocation into the vitreous
• UGH syndrome with AC-IOL
• Endothelial decompensation

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• THANK YOU