Cataracts

Question 1

what are iatrogenic causes of cataracts?

Answer 1

• Corticosteroid use (a/w posterior subcapsular cataract)
• Phenothiazines
• Copper
• Ionising radiation (overlap with trauma)

Question 2

what are ocular diseases that can cause cataracts?

Answer 2

• Chronic anterior uveitis (due to inflammation, use of steroids in treatment)
• Acute congestive angle closure glaucoma (AACG) (glaukomflecken formed)
• High myopia/pathological myopia
• Hereditary fundus dystrophies e.g. retinitis pigmentosa

Question 3

what are the systemic diseases that can cause cataracts?

Answer 3

• Diabetes mellitus (DM) [metabolic] (high glucose level in aqueous humour 🡪 diffuse into lens 🡪 metabolised into sorbitol 🡪 accumulates within lens 🡪 secondary osmotic overhydration)
• Myotonic dystrophy
• Atopic dermatitis [dermatological]
• Neurofibromatosis type 2 (NF2) [CNS disorders]

Question 4

what are congenital causes of cataracts?

Answer 4

• metabolic disorders: galactosaemia, Fabry disease
• intrauterine infections: Rubella, Toxoplasmosis, CMV, Varicella, others (measles, syphilis, HSV, HIV, etc) (TORCH infections)
• systemic associations: Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13), chromosome 5p deletion (Cri-du-chat)

Question 5

what are the symptoms of cataracts?

Answer 5

• gradual LOV as the lens become opacified (may be reported as sudden LOV sometimes)
• glare (halos or streaks around lights), especially for cortical and posterior subcapsular
• blurring (vision is better in dim light and worse in bright light)
• Loss of stereopsis if severe unilateral
• Increasing near-sightedness (index myopia) or change in refractive status (including “second sight of the aged” phenomenon) 🡪 suggests nuclear sclerotic (NS) cataract

Question 6

what are the traumas that can cause cataracts?

Answer 6

• Penetrating
• Blunt 🡪 characteristic flower-shaped opacity
• Electric shock (rare)
  Infrared radiation (if intense as in glassblowers)
• Ionising radiation exposure (e.g. for ocular tumour treatment)

Question 7

Complications of cataracts: Secondary glaucoma — A small fraction of mature and hypermature cataracts can give rise to secondary glaucoma. Three rare types of intractable glaucoma may occur:

• ________ glaucoma, in which lysed lens proteins cause a pressure rise
• __________ glaucoma, in which the autoimmune reaction to these proteins causes a pressure rise
• _______ glaucoma, in which the swollen lens causes a form of angle closure glaucoma

These types of glaucoma cause a red, painful eye; they are not asymptomatic like many other glaucoma

Answer 7

Phacolytic;

Phacoanaphylactic ;

Phacomorphic

Question 8

what are the benefits of using phacoemulsification therapy for cataracts?

Answer 8

• No sutures required
• Wound hydration causes oedema and self-apposition of wound edges, thus promoting healing
  faster recovery (faster visual rehabilitation)
• less surgically-induced astigmatism
• smaller wound (3-4 mm), less inflammation
• less % risk of progression to diabetic retinopathy (DR)

Question 9

what are the benefits of using extracapsular cataract extraction for cataracts?

Answer 9

• suitable for dense and brunescent cataract (i.e. very advanced nuclear cataracts that have become brown and opaque)
• suitable if there is lens instability
• less surgical trauma to endothelial cells

Question 10

what are the choice of intraocular lens for the cataracts patients?

Answer 10

• Monofocal (subsidised): will be targeted to correct for far vision; pts still need spectacles to correct for near vision
• Multifocal: potentially corrects for far and near vision (has concentric zones of different refractive index)
• Toric lens (can be mono- and multifocal): potentially corrects for astigmatism
• Monovision = 1 eye set for far vision (VA 6/6 post op) + 1 eye set for near vision (VA poorer than 6/6)

Question 11

what are the pre-operative complications of cataract surgery?

Answer 11

• Retrobulbar haemorrhage and scleral laceration from regional anaesthesia (risk is lower if using peribulbar anaesthesia)
• Bradycardia secondary to oculo-cardiac reflex

Question 12

what are the intra-operative complications of cataract surgery?

Answer 12

• Posterior capsule rupture (main intra-op risk)
• Vitreous in anterior segment 🡪 can cause tractional RD
• Suprachoroidal haemorrhage (rare but devastating)

Question 13

what are the post-operative complications of cataract surgery?

Answer 13

• Exogenous endophthalmitis* (follow-up patients 3-7 days post-op – when infection is likely to present) (early post-op) most feared
• Posterior capsule opacity* (PCO) most common (late post-op)
• Cystoid macular oedema (CMO)
• Corneal oedema (because of ultrasonic damage to endothelial cells that pump fluid out of endothelium, but is ± post op risk)
• Retinal detachment (risk of every intra-ocular surgery)
• Hyphaema

Question 14

what is Nd:YAG laser capsulotomy and what is it use for?

Answer 14

• indication: Posterior capsule thickening and opacification s/p cataract surgery (more commonly occurs 2 years after cataract surgery, less commonly occurring within months) but honestly the timing of PCO is extremely variable
• procedure: Directing a laser beam to the thickened and opacified capsule 🡪 create small opening in centre of capsule 🡪 allow light to pass through again