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Cataracts (Risk factors (Age, FH, Smoking, UVB light exposure, Steroid use…
Cataracts
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Pathophysiology
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Lens anatomy
Lens does 1/3 focusing (2/3 by cornea)
Inner nucleus, outer cortex
Transparent, covered by lens capsule
Zonule ligaments attach capsule to ciliary muscle
Lens physiology
Ciliary muscle contraction relaxes zonules, lens becomes convex and can focus close objects
Ciliary muscle relaxation causes taut zonules, pulling lens flat and allowing focus on distant objects
Ageing hardens the lens, less able to accomodate to focus on near objects (presbytropia); need weak converging lens (reading glasses)
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Clinical
presentation
Reduced vision
Gradual, painless
Reading, watching TV, seeing faces
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Diagnosis
Examination
Fundoscopy
Lens opacity seen, reduced red reflex;
white/grey pupil in babies (leukocoria)
CN examination
Reduced acuity, normal movements and pupil reflexes in adults;
nystagmus, strabismus in children
External eye examination
Signs of trauma, infection
Investigations
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Imaging
Slit lamp - type of cataract, severity
Special tests
Biometry: IOL power (corneal curvature, axial length of eye,
depth of anterior chamber, a-constant of lens)
History
DH
Steroids, other meds, allergies
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PMH
Eye infections, trauma, glaucoma,
DM, congenital disorders
SH
Occupation (sunlight exposure?),
living arrangements, smoking, alcohol
PC/HPC
Reduced vision, glare, double vision,
reduced colour vision
Management
Medical
Mydriatric drops
Indication: index myopia
Eg. cyclopentolate, tropicamide
MOA: dilate pupil, alllowing more light in
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Conservative
Information, advice, support
Encourage otometrist appontment
Refer babies/children to ophthalmology and adults if interfering with ADLs/underlying eye disease
Fitness to drive advice
Meiopic spectacles (reading glasses), sunglasses for glare
Aetiology
Adults
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Drugs
Steroids (topical, PO, inhaled)
Children
Congenital
Hereditary cataracts (AD, AR, X-linked)
Genetic syndromes (Down's, Edward's)
Infection
Viruses: rubella, VZV, CMV, HSV
Parasite: toxoplasmosis
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Prognosis
Adults
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High satisfaction rates with surgery,
complications are rare
Children
Without treatment, cause deprivation ambylopia
and serious visual impairment, even if later treated
Unpredictable/varied prognosis with surgery;
critical period for visual development in first 6-8wk of life
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Definition
Opacity of the crystalline lens
of the eye, reducing transparency
and visual acuity
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