Cataract
Features
• Painless, gradual loss of vision
• Glare, especially at night (haloes around lights)
• Blurred or cloudy vision
• Loss of red reflex (seen on fundoscopy)
Causes
• Age-related (most common)
• Diabetes mellitus (early onset, "snowflake" cataracts)
• Steroid use (systemic or topical)
• Trauma (especially blunt → rosette cataract)
• Radiation exposure
• Congenital: rubella, galactosaemia, hypocalcaemia
Management
• Phacoemulsification with intraocular lens implant
Lens Dislocation (Ectopia Lentis)
Causes
• Marfan syndrome: superotemporal (upwards and outwards)
• Homocystinuria: inferonasal (downwards and inwards)
• Trauma
Features
• Monocular diplopia
• Refractive changes
• Visible edge of lens on slit-lamp
Associated risks
• Secondary glaucoma (due to lens-induced angle blockage)
Presbyopia
Features
• Progressive difficulty with near vision (reading)
• Typically begins around age 40–45
• Due to loss of lens elasticity and reduced accommodation
Management
• Reading glasses (convex lenses)
Refractive Errors
Myopia (short-sightedness)
• Image focused in front of retina
• ↑ axial length of globe
• Poor distance vision, good near vision
• Associated risks: retinal detachment, myopic degeneration
Hypermetropia (long-sightedness)
• Image focused behind retina
• Short axial length
• Difficulty with near tasks (early), may also have accommodative strain for distance
• Predisposes to angle-closure glaucoma
Astigmatism
• Irregular corneal or lens curvature
• Blurred vision at all distances
• Corrected with cylindrical lenses
Extra Revision Pearls
• Halos at night clue → cataract or acute angle-closure glaucoma (with pain)
• Upward dislocation clue → Marfan; downward clue → homocystinuria
• Cataract risk clue → steroids, diabetes, radiation
• Hypermetropia clue → angle-closure risk due to shallow anterior chamber
• Myopia clue → retinal detachment risk (especially lattice degeneration)
• Presbyopia clue → common in middle age; convex "reading" correction
