Cataracts Flashcards
what are the acquired causes of catarcts?
AGE, UV light, trauma, smoking, alcohol, DIABETES, uveitis, systemic drugs (steroids), malnutrition, myotonic dystrophy, high myopia
what are the congenital causes of cataracts?
genetic, infection (intrauterine – rubella, CMV, toxoplasmosis)
what is the pathophysiology of cataracts?
- Laying down of fibres resulting in sclerosis of the nucleus
- Pigment also laid down, causing gradual browning of lens
- Oxidative stress altering protein structure of lens causing it to become opaque
what are the different types of cataracts?
nuclear, cortical, posterior subscapular, polychromatic, dot opacities, congenital, mature
what are the clinical features of cataracts?
- Painless loss of vision
- Hazy/blurring/misting
- Glare – due to light scattering
- Change in refractive error
- Manifests as – difficulty reading, difficulty recognising faces, problems driving – at night
- Cloudy lens.
- Reduced visual acuity
- Red reflex
what is the management of cataracts?
Surgery – Phacoemulsification
where to nuclear cataract occur?
nucleus of the lens
what is the pathophysiological process of nuclear cataract formation?
proteins suffer oxidative damage
protein crystallin’s, undergo crosslinking and form aggregates that scatter light. Biochemical changes result brown products = lens nucleus becomes cloudy, yellowish and then brown/green.
where do cortical cataract occur?
lens cortex (centre)
what is the pathophysiology of cortical cataract?
fibres affected arranged radially
affected zones have a radial, spoke like appearance and may be peripheral or extend more centrally
no impact on vision
where do posterior subscapular cataracts occur?
lies immediately deep to the posterior part of the lens capsule
what are the causes of posterior subscapular cataract?
follow X-radiation or blunt injury to the eye or vitreous surgery and if it occurs bilaterally in isolation, may imply steroid induced cataract.
what do posterior subscapular cataract look like?
ground glass appearance
what are the features of polychromatic cataracts?
highly reflective iridescence corneal crystals of various colours
when do dot opacities occur?
common in normal lenses, also seen in diabetes and myotonic dystrophy
