2. LENS
• Transparent, biconvex
• Diam : 9mm, thick: 4mm,
• Radius of curvature –
Ant :10mm , Post : 6mm
• Ref. index : 1.39
• Total diopteric power : +16 to
+20 D
• Lens is held by suspensory
ligaments – zonules of zinn
3. • STRUCTURE
1. Lens capsule :
-smooth, homogenous, highly elastic( no true elastic tissue)
- thickest(14u)- ant & post surface just central to insertion of
zonular fibres
-thinnest(3-4u)- posterior pole
2. Lens epithelium:
- single layer
-cuboidal cells
-no corresponding posterior epithelium
3. Lens substance : cortex & nucleus
-embryonic nucleus: 1st 3 months of fetal life
- fetal nucleus: 3-8 months of fetal life
- infantile nucleus- upto puberty
- adult nucleus- rest of life
7. Lens transparency
• Avascularity of the lens
• Characteristic of lens fibre:
- Tightly-packed nature of lens cells
- Narrow lens fibre membranes
- Loss of organelles
• Lens proteins-MTP 26 or Aquaporin 0
• Pump mechanism of lens fibre membranes that regulate
the electrolyte and water balance in the lens, maintaining
relative dehydration
• Auto-oxidation and high concentration of reduced
glutathione in the lens
8. Differential diagnosis
Painless, progressive
diminution of vision
• Cataract
• Primary open angle glaucoma
• Diabetic retinopathy
• Corneal dystrophies and degenerations
• Age related macular degeneration
• Retinitis pigmentosa
9. Cataract
• Development of any opacity in the lens or its capsule
either due to formation of opaque lens fibres (congenital
& developmental cataracts) or due to degenerative
process leading to opacification of normally formed
transparent lens fibres (acquired cataract)
• Major cause of blindness worldwide
• Classification-
-Etiological
-Morphological
10. Etiological classification
I. Congenital and Developmental cataract
II. Acquired cataract
• Senile cataract
• Traumatic cataract (blunt, penetrating, radiation,
electric shock, glass blowers, infra-red)
• Complicated cataract (uveitis-induced)
• Metabolic cataract (Diabetes - snowflake, Wilson’s
disease-sunflower)
• Drug induced cataract- corticosteroids, miotics
• Cataract associated with syndromes
12. Congenital & developmental
cataracts
• When the disturbance in the normal growth of lens
occurs before birth, the child is born with a congenital
cataract. Therefore, limited to either embryonic or foetal
nucleus.
• Developmental cataract may occur from infancy to
adolescence. Therefore, involve infantile or adult
nucleus, deeper parts of cortex or capsule.
13. ETIOLOGY
• Idiopathic
• Heredity-
-lnherited cases without systemic disorders- AD
-Inherited cases with systemic disorders include:
• Chromosomal disorders (trisomy 21)
• Skeletal disorders (Stickler syndrome)
• Central nervous system disorders (cerebro-oculo-facial
syndrome)
• Renal system disorders (Lowe's syndrome)
14. • Maternal factors include:
1. Malnutrition during pregnancy
2. Infections-Rubella,Toxoplasmosis,CMV
3. Drugs ingestion-thalidomide, corticosteroids
4. Radiation exposure
• Common familial cataracts include:
• Cataracta pulverulenta
• Zonular cataract (also occurs as nonfamilial)
• Coronary cataract and total soft cataract (may
also occur due to rubella).
15. • Foetal or infantile factors
1. Deficient oxygenation (anoxia)
2. Birth trauma
3. Metabolic disorders- galactosemia, galactokinase
deficiency and neonatal hypoglycemia
4. Cataracts associated with other congenital anomalies-
Down's syndrome, Lowe's syndrome, myotonia
dystrophica and congenital icthyosis
5. Ocular diseases associated with developmental
cataract-PHPV, aniridia anterior chamber cleavage
syndrome, ROP,microphthalmos
6. Malnutrition
17. Congenital capsular cataract
Anterior capsular cataracts are nonaxial,
stationary and visually insignificant.
Posterior capsular cataracts are rare and can be
associated with persistent hyaloid artery
remnants.
18. Anterior Polar Cataract
•Dense, usually circular and well-
defined opacity on the anterior
pole of the lens
•d/t delayed development of AC
•d/t corneal perforation
•May protrude slightly into the
anterior chamber like a small
pyramid
19. Posterior Polar Cataract
•Dense, usually circular and
well-defined opacity on
the posterior pole of the lens
•Usually symmetric; may be
misdiagnosed as posterior
subcapsular cataract
•2 forms-
1.)stationary
2.)progressive-onion whorl appearance
20. Mittendorf Dot
•An embryological
remnant of the hyaloid artery that is
attached to the posterior surface of
the lens
• appears as a small punctate opacity
•The lens may also have a
corkscrew "tail" of hyaloid artery
remnant attached to it
21. Cataracta centralis pulverulenta
•Embryonic nuclear cataract
•Hollow sphere of
punctate opacities involving
the fetal nucleus
•Subtle "bull's eye" may be
noted with ophthalmoscope
retro-illumination
•Usually bilateral
22. Zonular/Lamellar Cataract
• M/C Congenital cataract
presenting with visual
impairment
• Etiology-
• Genetic pattern-AD
• Environmental form is
associated with:
• vitamin D deficiency
• hypocalcaemia
• maternal rubella infection (7th
and 8th week of gestation)
23. Zonular/Lamellar Cataract
• occurs in zone of foetal
nucleus surrounding
embryonic nucleus
•Usually B/L,severe
visual defects
•Spokes of a wheel
(riders) seen towards the
equator
24. Sutural & axial Cataract
•Dense opacity that "gloves"
the Y-suture
•May involve the anterior
or posterior Y-suture or both;
however, the anterior is the
most common
• Static,B/L
• Don’t have much effect on
vision
25.
26. Total Nuclear Cataract
• Involves the embryonic and foetal nucleus and infantile
nucleus
• Dense chalky white central opacity impairing vision
• Bilateral
• Non-progressive
27. Coronary Cataract
•Single or multiple
finger- or bowling pin-shaped
opacities that ring the
peripheral cortex
•Often associated with
cerulean cataracts
28. Cerulean Cataract/Blue dot cataract
•Small, bluish punctate opacities
of the peripheral cortex
(anterior, posterior or both)
•Often associated with
other cataract types
•May exhibit sectoral
distribution but tends to
be symmetric OU
29. Epicapsular stars
•Small light brown or tan
dots or star-shaped deposits
on the anterior capsule
• single or multiple
• unilateral or bilateral
•Are remnants of the tunica
vasculosa lentis
31. Evaluation
• HISTORY
-Family history
-Growth & development history with milestones
• EXAMINATION
-Vision
-Visual function-fixation behaviour,fixation
preference,objection to occlusion,VEP
-Retinoscopy
32. Assessment of visual acuity
• <3yrs-Look for-
CSMF(central steady maintaining fixation)
Resistance to closure of eye
• 3-6yrs-
-Illiterate E chart
-Landolt acuity card
-Teller acuity card
-Keeler acuity card
• >6yrs- Snellen’s chart
33. • SLIT LAMP EXAMINATION—
-Morphology of the cataract and its laterality
-Corneal diameter & clarity
-Iris configuration AC depth
-Lens position
• Fundus exam. If possible or B-scan
• Examination of immediate family of the affected child
• Check for strabismus and nystagmus
• Check IOP
34. Ophthalmic Evaluation
Visual Significance : Concept of “ functional cataract ”
• Assessment of red reflex
( before and after dilatation )
• k/c/o Bruckner test
• For detection of visual axis
opacities,strabismus,refractive errors and retinal
abnormalities
• To assess density and morphology of cataract
36. Ophthalmic Evaluation – EUA
• Axial length for prognosis / IOL calculation
• Keratometry
• Morphological evaluation of cataract with slit lamp
under EUA whenever possible
• B scan to assess posterior segment
38. Surgery -indications
• Visually significant cataract-U/L or B/L
• U/L dense cataracts
• Central and >3mm
• Cataract with Strabismus
• Cataract with nystagmus or unsteady fixation
• One eye operated in a binocular cataract
39. Timing of surgery
• Visually significant B/L congenital -6 weeks of age (Each
eye one week apart- to prevent amblyopia)
• U/L visually significant cataract -4-6 weeks
• B/L cataract detected later-surgery as soon as
possible.First on the worse eye.
• Increased rates of post-op glaucoma in first 4 weeks of
life
40. Power of IOL
• Myopic shift with growing age-undercorrect
DAHAN’S criteria
• <2 years-undercorrect by 20%
• 2-8 years-undercorrect by 10%
Axial length (mm) IOL power
17 25
18 24
19 23
20 21
21 19
41. Lens material
• Single piece PMMA,preferably heparin coated
• Hydrophobic –uveal biocompatibility,reduced PCO
• IOL size -<2 yrs , 10-10.5 mm IOL
- >2 yrs , 12-13.5 mm IOL d/t elastic nature of the capsule
42. Surgical techniques
• Needling and aspiration-obsolete
• Lensectomy - < 2 yrs
• Lensectomy with PPC,Anterior vitrectomy(AV),IOL- >2
yrs but <6-7 YRS
• Lens aspiration with Primary Posterior Capsulotomy(PPC)
and IOL - >7 YRS
• Lens aspiration with IOL- >9-10 YRS
43. Correction of paediatric aphakia
• >2 yrs – PC-IOL implantation
• <2 yrs-
-Left aphakic
-Extended wear contact lens
-In B/L cases, spectacles are prescribed
• Children with JIA,PFV,microcornea,microphthalmos are
left aphakic
44. Post-op rehabilitation
• Glasses-B/L aphakia,residual correction
• Contact lens-U/L aphakia
• Secondary IOL- if myopic shift is >7D or contact lens not
viable option
45. Amblyopia Mx
• Occlusion theraphy of sound eye
• Spectacles >4 months age
• Bifocals >3 years age
