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Ophthalmology > Cataracts > Flashcards

Cataracts Flashcards

1
Q

Definition of cataracts

A

Opacity of lens.
There is fluid accumulation bw lens fibres causing refractory error
This causes light scatter and blurred vision

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2
Q

Lens anatomy - what is connected to the lens

A

Zonule filaments attach to lens capsule at equator of lens
Arise from and connect lens to ciliary body
Ciliary body contains ciliary muscle that contract/relax to lax/taught zonules in accommodation

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3
Q

Lens anatomy - what are the layers of the lens

A

Capsule - thickened basement membrane that surrounds the lens
Cortex - softer, layers of new lens fibres
Nucleus - dense core, older lens fibres

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4
Q

Lens anatomy - components of lens

A

Epithelium - epithelial cells cover the lens, undergo mitosis, epithelial cells at equator produce lens fibres
Lens fibres - laid down subcapsularly, older layers migrate deeper, tight + regular organisation to allow transparency

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5
Q

Lens anatomy - location of lens

A

Posterior to iris
Anterior to vitreous
Vitreous + zonules jeep lens in position

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6
Q

Types of cataracts

A

Cortical
Posterior subcapsular
Nuclear sclerotic

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7
Q

Causes of cataracts

A

Old age
Ocular diseases
Drugs: steroids, phenothiazines
Trauma: surgery, foreign bodies
Ionising radiation: X Ray, UV
Congenital cataracts (sporadic, dominant, abnormal galactose metabolism)
Genetic conditions: Marfan’s syndrome (also cause lens dislocation because abnormal Zonules), myotonic dystrophy, High myopia

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8
Q

Risk factors accelerate cataract development. What are the risk factors

A

Systemic: DM, myotonic dystrophy, Wilson’s disease
Ocular: trauma, ocular surgery, inflammatory eye disease
Congenital: metabolic disorders
Drugs: steroids, amiodarone, phenothiazines

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9
Q

Pathophysiology of cataracts

A

Protein denaturation due to various factors:
Metabolic disturbance (glycaemia, uricaemia)
Toxins
Membrane damage
Osmotic imbalance
Oxidative damage

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10
Q

Clinical features of cataracts

A

Symptoms:
Vision - acuity, contrast sensitivity, colour vision, glare, monocular Diplopia
Refractory - myopia, astigmagism

Signs:
Dim red reflex
Nuclear - central black shadow
Cortical - black spokes from the edge

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11
Q

Natural history of cataracts

A

Initially:
refractory myopia due to increased refractive power from cataracts
Management by optometrists with minus lenses

Later stage:
Refractory error cannot be corrected by minus lenses, or other symptoms develop, or under special circumstances
Referral for cataract surgery

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12
Q

Referral criteria for cataracts

A

Best-corrected visual acuity <6/12
Monocular diplopia
Glare (sun light, car lights; posterior subcapsular)
Clouding of vision (cortical)
DM patients (impairs retinal monitoring)
Phacomorphic glaucoma (swollen lens push iris, narrowing of Irido-corneal angle)
Poor VA from other causes (e.g. ARMD; to improve colour contrast)
Children (prevent stimulus deprivation amblyopia)

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13
Q

Cataracts Pre-op management - what is biometry

A

Involves Uss measurement of eye length and keratometry to measure corneal curvature
To decide strength of intraocular lens + site of incision on cornea
Special equation used to calculate IOL power needed (19-22D, lower if very shortsighted)

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14
Q

Cataracts pre-op management - medical pre-assessment

A

Anticoagulants: warfarin not stopped, use topical LA if not stopped
Tamsulosin: causes floppy iris syndrome
Control of medical conditions: esp DM, HTN, respiratory disease

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15
Q

Cataract surgery terminology - what is phakia, pseudophakia, aphakia

A

Phakia: Eye with natural lens in situ
Pseudophakia: Eye with cataract removed and intraocular lens implanted
Aphakia: Eye with cataract removed without artificial lens inserted

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16
Q

Cataract surgery - types of local anaesthesia

A

Topical: drops of proxymethocaine; full kinesis of EOM, less risk of retrobulbar haemorrhage
Subtenons: dissect conjunctiva + Tenons capsule inferomedially (Away from iris), Lidocaine into subtenon space w cannula
Peribulbar: inject Lidocaine through skin or conjunctiva
Retrobulbar: inject Lidocaine into muscle cone, high risk of retrobulbar haemorrhage

17
Q

Cataract surgery - type of incision

A

Depends on keratometry
Incision at steeper axis because incision will flatten this axis + steepen axis 90 degrees to this
Thus reduce astigmatic error

18
Q

Cataract surgery - importance of draping

A

Eyelids + eyelashes covered with thin plastic tape
Keep eyelashes out of surgical field
Main source of infection (staphylococci), prevents oily secretions

19
Q

Cataract surgery - type of surgery and its procedure

A

Phacoemulsification and intraocular lens

  1. Incision
  2. Viscoelastics: polymer solution injected into anterior chamber, maintain AC, stabilise capsule, prevent posterior capsule tear, prevent retinal tear, and protects corneal endothelium
  3. Circular hole made in anterior capsule
  4. Hydrodissection: water injected bw lens and capsule
  5. Phacoemulsification: divide + conquer; high frequency uss divide lens into 4 fragments, fragments emulsified + irrigated
  6. Soft lens matter (cortical lens) irrigated
  7. IOL implanted
  8. Wound sealing (suturing not needed)
20
Q

Cataracts surgery post op management

A

Discharged as day cases
Steroid + abx drops 2-4 weeks
Spectacles prescribed 6 weeks after surgery

21
Q

Cataract surgery post op complications - early non sight threatening

A

Raised IOP: pain + blurred vision; tx = systemic acetazolamide, glaucoma drops
Leaking incision: tx = soft contact lens, suturing
Corneal oedema: tx = increase steroid drops
Conjunctival/corneal erosion: gritty, watering
Subconjunctival haemorrhage: painless red eye
Conjunctivitis: tx = another topical abx, prevent endophthalmitis

22
Q

Cataract surgery post op complications - sight-threatening types and time frame

A

Acute (5 days): endopthalmitis
Subacute (6 weeks): macular oedema
Chronic (months-yrs): posterior capsular opacification, retinal detachment, bullous keratopathy

23
Q

Cataract surgery post op complications - endopthalmitis definition, features, management

A

Infection of whole eye, typically staph epidermidis

Painful red eye, discharge, visual loss
Hypopyon, fibrin plaque, loss of red reflex

Urgent inpatient management, topical broad spectrum abx

24
Q

Cataract post op complications - macular oedema features and management

A

Drop in vision after surgery, distortion
Oedema on slit lamp fundus exam

Topical steroid + nsaid drops
Systemic nsaid
carbonic anhydrase inhibitors

25
Q

Cataract surgery chronic complications - posterior capsular opacification: definition, features, treatment

A

Opacity of posterior capsule due to protein accumulation, w certain lens types or left over soft lens matter

Gradual loss of vision, similar to cataracts

Hole in capsule with YAS laser

26
Q

Cataract surgery chronic complications - retinal detachment cause

A

Posterior capsular tear

Leads to leakage of vitreous into anterior chamber

27
Q

Cataract surgery chronic complications - bullous keratopathy: definition, cause

A

Painful bullae in cornea

Endothelial cells pump fluid back into AC
Endothelial cells can be scraped off in surgery
Because surgical field bw corneal endothelium and anterior capsule v narrow

Ophthalmology (7 decks)

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