This document discusses various disorders of the crystalline lens, including disorders of lens shape and position such as coloboma, lenticonus, lentiglobus, microphakia, and ectopia lentis. It also discusses cataracts, providing classifications based on age, stage, morphology, etiology, and associations with ocular and systemic diseases. Specific lens disorders are described in detail, along with risk factors and pathologies of various types of cataracts.

1. DISORDERS OF THE
CRYSTALLINE LENS
Dr Russell J Watkins

2. Disorders of Lens Shape &
Position
 Coloboma
 Congenital
 Zonules absent also → lens rim relaxation
 Affects lower quadrants
 Associated with iris, choroidal, & optic nerve
colobomata
 Associated with giant retinal tears

6. Disorders of Lens Shape &
Position
 Lenticonus
 Anterior or posterior coning of lens surface
 ‘Oil drop sign’ against red reflex
 Irregular myopic lenticular astigmatism
 Anterior & posterior lenticonus are associated
with cataract
 Lentiglobus
 Generalised hemispherical deformity

9. Disorders of Lens Shape &
Position
 Microphakia
 Small lens due to arrested lens development
 Microspherophakia
 Small spherical lens, usually bilateral
 Zonule visible on pupil dilatation
 Iridodonesis & sometimes pupil block
glaucoma
 Zonular rupture common
 Isolated/familial or associated with Marfan’s
syndrome

12. Disorders of Lens Shape &
Position
 Ectopia lentis
 Subluxation or dislocation of the lens due to
zonular rupture
 → Loss of accommodation
 → Refractive error
• Myopia or astigmatism if subluxation (lens
tilt)
• Hypermetropia if dislocated
 Can → glaucoma & uveitis

15. Disorders of Lens Shape &
Position
 Causes of a dislocated lens
 Can be hereditary (Marfan’s, homocysteinuria,
familial et al)
 Can be acquired (trauma, couching,
buphthalmos, anterior uveal tumours,
spontaneous [hypermature cataract], high
myopia, chronic anterior uveitis)

19. Lens-induced Disorders
 Glaucoma
 Phakomorphic (caused by lens shape/size)
 Phakolytic (capsular leakage)
 Lens displacement
 Uveitis
 Phakoanaphylactic (AI sensitivity to lens
protein)
 Phakotoxic (toxic reaction to lens protein)

22. Cataract
 Lens opacity or cataract?
 WHO estimates worldwide
there are 15 million blind
(<3/60) from cataract
 CATARACT IS THUS THE
MOST COMMON CAUSE OF
BLINDNESS WORLDWIDE

23. Cataract Classification
 According to age
 Congenital
 Infantile
 Juvenile
 Presenile
 Senile

24. Cataract Classification
 According to stage
 Immature
 Stationary
 Progressive
 Mature
 Intumescent
 Hypermature (morgagnian)

25. Cataract Classification
 According to morphology
 Capsular
• Congenital - anterior polar; pyramidal
• Acquired - infrared, mercury (grey),
chlorpromazine (white star)
 Subcapsular
• Posterior - senile or 2° e.g. myotonic
dystrophy or corticosteroid use
• Anterior - glaukomflecken, miotics, Wilson’s
disease (green sunflower)

26. Cataract Classification
 According to morphology
 Cortical
• Congenital - blue/brown dot; coronary
• Acquired - senile cuneiform, Christmas tree
 Nuclear
• Congenital - embryonal; lamellar [± riders]
(genetic, metabolic, infective causes)
• Acquired - senile nuclear sclerosis

27. Cataract Classification
 According to aetiology
 Not associated with ocular or systemic disease
 Associated with ocular disease
 Associated with systemic disease

28. Causes Of Congenital Cataract
 Idiopathic (largest group - 40%)
 Hereditary (25%) - usually AD
 Remaining 35%
 Maternal infection, drug ingestion,
malnutrition
 Inborn errors of metabolism
 Chromosomal abnormalities
 Uveitis
 Prematurity
 50% are associated with other ocular anomalies

44. Cataract not Associated with
Ocular or Systemic Disease
 Senile cataract - 90% of >70yr age group
 Type
 Anterior subcapsular (fibrous metaplasia)
 Posterior subcapsular (epithelial migration)
 Cortical
 Nuclear cataract (exaggerated aging process)

45. Cataract not Associated with
Ocular or Systemic Disease
 Risk factors for senile cataract
 Smoking
 Dehydration (e.g. diarrhoeal illness)
 UV light exposure
 ?↓ by NSAIDs

46. Pathology of Cataract
 Changes in crystallins by deamination, glycosylation,
carbamoylation, accelerated by RFs, cause
 Protein unfolding
 Disulphide cross-links
 Removal of positive charge from cells
 Exposure of hydrophobic sites
 Protein aggregation & ↑ insoluble protein
 These pathological changes produce opacification by
 Altering refractive index, especially at interfaces
 Forming large protein aggregates

64. Cataract Associated with
Ocular Disease
 Congenital disorders
 Aniridia
 Hyperplastic primary vitreous
 Hereditary retinal & vitreoretinal disease

65. Cataract Associated with
Ocular Disease
 Acquired disorders
 Uveitis
 Glaucoma (glaukomflecken)
 Myopia
 Retinal detachment
 Neoplasia
 Drug Rx e.g. miotics, corticosteroids
 Trauma [contusion → Vossius’ ring; lens
rupture; retained IOFB; electric shock;
radiation; alkali burns]

70. Cataract Associated with
Systemic Disease
 Intrauterine factors
 Maternal rubella - fetal risk 80% in 1st
trimester
• General features - stillbirth; deafness
(90%); CVS defects; small babies;
psychomotor retardation; chest infection
• Ocular features - 30-60%; cataract in 50%,
uni- or bilateral, nuclear or diffuse;
microphthalmos (15%); ‘salt & pepper’
retinopathy; glaucoma (10%); strabismus;
nystagmus; refractive errors; optic atrophy

71. Cataract Associated with
Systemic Disease
 Intrauterine factors (continued)
 CMV
• General features - low birth weight;
jaundice; enlarged spleen & liver; chest
infection; deafness; fits; psychomotor
retardation
• Ocular features - cataract; uveitis;
microphthalmos; optic nerve hypoplasia;
optic nerve coloboma; optic atrophy;
chorioretinitis
 Drug ingestion
 Radiation exposure

72. Cataract Associated with
Systemic Disease
 Chromosomal abnormalities e.g.
 Down’s syndrome (snowflake cataract)
 Hereditary disorders
 E.g. Marfan’s syndrome
 Retinitis pigmentosa syndromes
 Systemic drugs
 E.g. corticosteroids, antimitotics,
chlorpromazine

73. Cataract Associated with
Systemic Disease
 Cutaneous disorders
 E.g. Atopic dermatitis → anterior or posterior
stellate cataract; also associated with
keratoconjunctivitis & keratoconus
 Muscular disorders
 Myotonic dystrophy (AD) → ptosis; Christmas
tree cataract [cortical polychromatic dusting];
light near dissociation; pigmentary retinal
changes

79. Cataract Associated with
Systemic Disease
 Metabolic disease (there are many associated
with cataract. The important ones are:)
 Diabetes mellitus → bilateral white snowflake
cataract - may progress rapidly. Also
accelerated senile cataract
 Wilson’s disease (hepatolenticular
degeneration) - green sunflower cataract. Also
causes Kayser-Fleischer ring at level of
Descemet’s membrane