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Types of Cataract
By
Prof. Naimatullah Khan KundiHead, Department of Ophthalmology
Khyber Teaching Hospital Peshawar
Metabolic Cataract Diabetes Mellitus
True diabetic cataract rare Snow storm opacities – subcapsular
opacities in young uncontrolled diabetics ↑ blood sugar – myopia ↓ blood sugar – hyperopia Lens uses glucose through four
pathways Glycolysis Pentose shunt Kreb’s cycle Sorbitol pathway
Pathways for glucose metabolism in the lens
Metabolic Cataract
Metabolic Cataract
Diabetes Mellitus
Glycolysis, Pentose shunt and Kreb’s cycle
depend on glucose – 6 – P
At high glucose level Hexokinase saturated
Sorbitol pathway becomes significant
Metabolic Cataract
Metabolic Cataract
Metabolic Cataract Diabetes Mellitus
Sorbitol sugar can not defuse through lens fibers ↑ intralenticular osmolarity Water is drawn Water vacuoles developed Hydropic lens fibers more permeable and rupture Na+ influx → further water absorption Loss of K+, AA, glutathione and proteins
Metabolic Cataract
Metabolic Cataract Galactosemia
Types Transferase deficiency type (classic) Galactokinase deficiency type (milder)
Transferase deficiency type Galactose – 1 – PO4
uridyl tranferase deficiency Cataract
75% Droplet opacities Anterior/posterior
Metabolic Cataract
Metabolic Cataract
Galactosemia
Galactokinase deficiency type
Features
Infantile cataract
Metabolic Cataract
Metabolic Cataract Pathogenesis
Dulcitol, sugar similar to sorbitol causes osmotic swelling with lens fiber membrane damage and ↑ permeability
Diagnosis Reducing sugars in urine
Treatment Elimination of lactose and glactose from the diet
and replacing with synthetic formulas for milk and milk products.
Metabolic Cataract
Metabolic Cataract
Metabolic Cataract Hypocalcaemia
Infantile tetany Hypo para thyroidism Rickets
Punctate opacities in subcapsular area With treatment these opacities sink and
form lamellar cataract Progression to maturity
Metabolic Cataract
Metabolic Cataract
Wilson’s disease
Deposition of metallic copper in the lens
capsule
Sun flower cataract
Glaucomatous flecks
Cataracta glaucomatosa Multiple white punctate opacities in
anterior subcapsular clear zone due to damage of the lens epithelium
Vaculation of subcapsular cortex with focal necrosis of affected fibers and adjacent epithelium
With time opacity sink
Dermatogenic Cataract
Skin and lens – Ectodermal Cataract BL Young age Atopic dermatitis
Allergic condition with familiar tendency PSC 10% Most common skin disease associated with
cataract Other skin diseases
Rothmund syndrome Werner’s syndrome
Infectious diseases associated with cataract Viral
Congenital rubella syndrome Congenital cytomegalovirus disease Herpes simplex Variola (small pox)
Treponemal Congenital syphilis
Protozoal Congenital toxoplasmosis
Nematode Onchocerciasis
Cataract associated with systemic disease Dystrophica myotonica
Autosomal dominant Excessive contractility and slow relaxation of
muscles PSC 90% Ptosis Retinal pigmentary degeneration Sluggish pupillary response
Down’s syndrome Other syndromes