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DISEASES OF THE
CRYSTALLINE LENS
I. CONGENITAL DISORDERS OF LENS SHAPE AND POSITION
1. Coloboma
a. Congenital
b. Absence of segment of zonule
c. Lens rim relaxes
d. Lower quadrants
e. Associated with iris, choroidal and optic nerve colobomata and giant retinal tears
2. Lenticonus
a. Conical shape relative to lens surface
b. Anterior or posterior
c. Oil drop sign on eliciting red reflex
d. Irregular myopic lenticular astigmatism
e. Anterior lenticonus associated with cataract and Alport’s syndrome:
* Basement membrane disorder
* Autosomal recessive, but may be AD or x-linked
* Anterior lenticonus
* Endothelial changes
* Cataract
* Spherophakia
* Deafness
* Nephritis
f. Posterior lenticonus unilateral associated with cataract or bilateral which may be familial or associated with LOWE syndrome
3. Lentiglobus: generalized hemispherical deformity
4. Microphakia
a. Small lens due to arrested lens development
b. Associated with Lowe's syndrome
5. Microspherophakia
a. Small spherical lens, usually bilateral
b. Zonule visible on pupillary dilatation
c. Iridodonesis
d. Zonular rupture common
e. Pupil block glaucoma occurs
f. Associations
(i) Familial
(ii) Weill-Marchesani syndrome
(iii) Marfan's syndrome
(iv) Hyperlysinaemia
(v) Ocular: Peter’s anomaly
6. Ectopia lentis
a. Subluxation or dislocation of lens
b. Results from zonular rupture
c. Produces loss of accommodation
d. Refractive errors may occur
(i) Subluxation: myopia or astigmatism
(ii) Dislocation: hypermetropia
e. Glaucoma due to lens position or uveitis
7. Mittendorf dot: behind the lens (remnant of anterior hyaloid artery)
II. CAUSES OF LENS DISLOCATION
1. Hereditary causes (Ectopia lentis)
a. Marfan’s syndrome
b. Weill-Marchesani syndrome
c. Homocystinuria
d. Ehlers-Danlos syndrome
e. Sulphite oxidase deficiency
f. Hyperlysinaemia
g. Familial ectopia lentis (autosomal recessive)
h. Aniridia
2. Acquired causes
a. Trauma
b. Buphthalmos
c. Anterior uveal tumours
d. Syphilis
e. Spontaneous (hypermature cataract)
f. High myopia
g. Chronic uveitis
h. PXS
Marfan's syndrome
- Autosomal dominant
- Mesodermal dysplasia
- Possible defect of collagen cross linkages (defective fibrillin ’glycoprotein’ responsible for extracellular microfibrillary network)
- Increased hydroxyproline and desmosine excretion
- General features
a. arm span > height
b. Dissecting aortic aneurysms
c. Aortic regurgitation
d. Arachnodactyly
e. High arched palate
f. Muscular underdevelopment
g. Hyperextensible joints
- Ocular features
a. Bilateral upward subluxation
b. Nonprogressive subluxation, accommodation retained.
c. Microspherophakia
d. Angle anomalies (glaucoma)
e. Hypoplastic iris dilators
f. Cornea plana and keratoconus
g. Axial myopia
h. Vitreoretinal degeneration and retinal detachment
Weill-Marchesani syndrome
- Autosomal recessive
- Disorder of connective tissue
- General features
a. Mental retardation
b. Short stature
c. Stubby fingers
d. Joint stiffness
- Ocular features
a. Microphthalmos
b. Myopia (-10 to -20 D)
c. Microspherophakia
d. Inferior, anterior or posterior dislocation of lens
e. Glaucoma secondary to lens dislocation
Homocystinuria
- Autosomal recessive
- Deficiency of cystathionine synthetase
- Variable activity produces variable clinical picture
- Accumulation of methionine and homocysteine
- Nitroprusside urine test and aminoacid assays are diagnostic
- General features
a. Skeletal — osteoporosis, fractures
b. CNS—mental retardation, seizures
c. CVS — malar flush, thromboemboi (especially after general anaesthetic)
- Ocular features
a. Acquired zonular damage
b. Downward subluxation
c. Staphylomas
d. Buphthalmos, myopia
e. Glaucoma
f. Vitreoretinal degenerations
- Treatment
a. Vitamin B6 (50% respond)
b. Methionine-restricted diet
c. Supplementary cysteine
d. Folate
Ehlers- Danlos syndrome
- Autosomal dominant
- Autosomal recessive or X-linked recessive
- Major defect of type III collagen
- Nine types, variable presentation
- General features
a. Hyperextensible joints
b. Hyperextensible skin
c. Easy bruising
d. Poor wound healing
- Ocular features
a. Easy lid eversion (Metenier's sign)
b. Epicanthic folds
c. Myopia, microcornea
d. Blue sclera
e. Keratoconus
f. Ectopia lentis
g. Vitreous haemorrhage
h. Angioid streaks
j. Retinal detachment
Sulphite oxidase deficiency
- Autosomal recessive
- Possible deficiency of molybdenum
- Increased urinary sulphite
- General features
a. Mental retardation
b. Frontal bossing
- Ocular features
a. Enophthalmos
b. Ectopia lentis
c. Brushfield spots
Hyperlysinaemia
- Autosomal recessive
- Deficiency of lysine dehydrogenase
- General features: * Motor, mental, and growth retardation
- Ocular feature: * microspherophakia
III. CATARACT
- Any opacity within the lens
- Classification
1. According to age
a. Congenital
b. Infantile
c. Juvenile
d. Presenile
e. Senile
2. According to stage
a. Immature
b. Stationary
c. Progressive
d. Mature
e. Intumescent
f. Hypermature (Morgagnian)
3. According to morphology
a. Capsular
(i) Congenital: anterior polar, pyramidal
(ii) Acquired: infra red (glassblowers), mercury (grey), ‘chlorpromazine’ (white star)
b. Subcapsular
(i) Posterior: senile or secondary, e.g. dystrophia myotonica
(ii) Anterior: glaucomflecken, Wilson’s disease (green sunflower), miotic therapy
c. Cortical
(i) Congenital: blue/brown dot, coronary(supranuclear)
(ii) Acquired: senile cuneiform
d. Nuclear
(i) Congenital: embryonal (cataracta centralis pulverulenta), lamellar with or without riders (genetic, metabolic and infective causes)
(ii) Acquired: senile nuclear sclerosis
4. According to aetiology
a. Not associated with ocular disease
b. Associated with ocular disease
c. Associated with systemic disease
Senile (Idiopathic) cataract
- 90% of > 70 year age group
- Types:
a. Anterior suucapsular due to fibrous metaplasia
b. Posterior subcapsular due to epithelial cell migration
c. Cortical
d. Nuclear cataract is an exaggeration of ageing process
- Risk factors
(i) Smoking
(ii) Dehydration, e.g. diarrhoea
(iii) Ultraviolet light exposure
Complicated cataracts associated with ocular diseases
1. Congenital disorders
a. Aniridia
b. Hyperplastic primary vitreous
c. Hereditary retinal disease
d. Hereditary vitreoretinal disease
2. Acquired disorders
a. Uveitis
b. Glaucoma (glaucomflecken)
c. Myopia
d. Retinal detachment
e. Neoplasia
f. Drug treatment, e.g. steroids, miotics
g. Trauma
(i) Contusion (Vossius’ ring)
(ii) Rupture of lens
(iii) Retained intraocular foreign body (siderosis, chalcosis)
(iv) Electric shock
(v) Radiation
(vi) Alkali burns
Complicated cataracts associated with systemic disease
1. Maternal infection
a. Rubella
- 15% of childbearing women susceptible
- Longlasting immunity follows infection
- Fetal risk 80% in first trimester
- General features
(i) Stillbirth or abortion
(ii) Deafness (90%)
(iii) Cardiovascular defects, e.g. patent ductus arteriosus
(iv) Intrauterine growth retardation
(v) Psychomotor retardation
(vi) Pneumonitis
- Ocular features
(i) Occur in 30-60% of cases
(ii) Cataract in 50%. Unilateral or bilateral. Nuclear or diffuse
(iii) Viable virus in lens for 3 years
(iv) Intense uveitis on lens extraction
(v) Microphthalmos (15%)
(vi) Retinopathy with 'salt and pepper' appearance
(vii) Glaucoma (10%)
(viii) Strabismus, nystagmus, refractive errors and optic atrophy
b. Cytomegalovirus inclusion disease
- General features
(i) Low birth weight
(ii) Hepatosplenomegaly, jaundice
(iii) Purpura, pneumonitis
(iv) Cerebral calcification, deafness
(v) Psychomotor retardation, seizures
- Ocular features
(i) Cataract
(ii) Uveitis, microphthalmos
(iii) Optic nerve hypoplasia, coloboma and atrophy
(iv) Chorioretinitis
c. Toxoplasmosis
- General features: Nervous system
(i) Convulsions
(ii) Mental retardation
(iii) Intracranial Calcification
- Ocular features: Chorioretinal scars
2. Maternal drug ingestion
3. Maternal radiation
4. Chromosomal abnormalities: e.g. Down’s syndrome (snowflake cataract)
5. Hereditary disorders: e.g. Marfan’s syndrome and syndromes associated with retinitis pigmentosa
6. Cutaneous disorders
a. Atopic dermatitis
(i) Anterior or posterior stellate cataract
(ii) Chronic keratoconjunctivitis
(iii) Keratoconus
b. Werner's syndrome (scleropoikiloderma)
c. Schaefer’s syndrome (congenital dyskeratoses)
d. Rothmund’s syndrome (infantile poikiloderma)
e. Congenital ichthyosis
7. Systemic infections: e.g. syphilis
8. Systemic drugs: e.g. steroids, antimitotics and chlorpromazine
9. Metabolic disorders
a. Diabetes mellitus (bilateral, white snowflake and may progress rapidly)
b. Hypoglycaemic cataract
c. Galactosaemia
- Autosomal recessive
- Impairment of galactose metabolism, excess reduced to dulcitol
- Initially lens clear, osmotic cataract develops
- Types:
(i) Galactose-l-phosphate uridyltransferase deficiency
- General features
* Onset in infancy with failure to thrive
* Renal disease
* Hepatosplenomegaly, cirrhosis
* Anaemia, deafness
* Mental retardation
* Death unless milk and derivatives removed from diet
(ii) Galactokinase deficiency
- General features: * Systemically well
* Mild galactosaemia possibly associated with presenile cataract
d. Mannosidosis
- Alpha-mannosidase deficiency
- General features: ‘Hurler-like’ syndrome (mental retardation, short stature, skeletal changes, hepatosplenomegaly)
- Ocular features
(i) Posterior spoke-like capsular opacity
(ii) No corneal changes unlike Hurler's syndrome
e. Fabry’s disease
- Alpha-galactosidase A deficiency
- X-linked
- Deposition of glycosphingolipids in tissues
- General features
(i) Angiokeratomas; dark red
(ii) Cardiovascular disorders
(iii) Renal disorders, A-V fistula
(iv) Bouts of pain in digits
- Ocular features
(i) Cornea verticillata
(ii) Spoke-like cataract (25%)
f. Lowe’s syndrome
- Defect of amino acid metabolism
- General features
(i) Males > Females
(ii) Mental retardation
(iii) Renal dwarfism
(iv) Osteomalacia
(v) Muscular hypotonia
(vi) Frontal prominence
(vii) Aminoaciduria
- Ocular features
(i) Congenital glaucoma (50%)
(ii) Congenital cataract (100%)
(iii) Small disc-like lens opacities in mother
g. Wilson’s disease
- Alpha-2-globulin (ceruloplasmin) deficiency
- General features: *Hepatolenticular degeneration
- Ocular features
(i) Kayser Fleischer ring
(ii) Green sunflower cataract
h. Hypocalcaemia due to hypoparathyroidism or pseudohypoparathyroidism (short stature and short 4th and 5th metacarpals)
- Ocular features: * White dot or coloured crystal opacities
10. Muscular disorders: e.g. Dystrophia myotonica
Dystrophia Myotonica
- Autosomal dominant
- Presented in 3rd decade
- General features
a. Wasting (temporalis, sternomastoid, facial ms., quadriceps, shoulder ms.)
b. Mournful expression
c. Frontal balding
d. Myotonia: Excessive contractility of muscles with difficult release of grip
e. Slurred speech
f. Hypogonadism
g. Cardiac defects and pulmonary complications
- Ocular features
a. Ptosis and ophthalmoplegia
b. Christmas tree cataract (cortical polychromatic dusting)
c. Light/near dissociation
d. Pigmentary retinal changes
Causes of congenital cataracts
1. Heredity (25% of congenital cataracts). Usually autosomal dominant
2. Maternal infection, e.g. rubella, cytomegalovirus
3. Maternal drug ingestion
4. Maternal malnutrition, e.g. vitamin D deficiency
5. Metabolic disorders, e.g. galactosaemia, hypocalcaemia, amino aciduria (Lowe's syndrome)
6. Chromosomal abnormalities, e.g. Down's syndrome
7. Systemic disorders, e.g oxycephaly
8. Intraocular disease, e.g. uveitis
LENS INDUCED DISORDERS
1. Glaucoma
a. Phacomorphic (due to lens shape)
b. Phacolytic (due to capsular leakage)
c. Lens displacement
2. Uveitis
a. Phacoanaphylactic (autoimmune sensitivity to lens protein)
b. Phacotoxic (toxic reaction to lens protein)
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