Cataract

Question 1

Where does the lens sit?

Answer 1

Lens sits in anterior segment of eye – with suspensory ligaments attached to ciliary body
Lens has capsule – divided into anterior and posterior aspects.
Posterior aspect has live and feeding cells which produce lens fibres
As lens fibres mature, they are compacted into central part of lens (nucleus)

Question 2

What is the function of human lens?

Answer 2

• Refractive
  o One third of optical power (approx. 18-20D out of 60D)
  o Rest of refractive power by cornea
• Accommodation

Question 3

What is the pathogenesis of cataract?

Answer 3

• Protein denaturation
  o When lens fibres are produced from posterior capsular epithelial cells, they are transparent but as we get older the proteins in the lens fibres denature & proteins in lens fibres is opaque (manifesting as cataract)
• Oxidative damage
  o Can occur naturally or artificially

Question 3

What are the risk factors of cataract?

Answer 3

• Age
• Smoking
• Alcohol
• Dehydration
• Radiation
• Diabetic – can have cataract at younger age as their metabolism is different and oxidative damage is thought to play role here
• Steroids – e.g. asthmatic pxs often present earlier in life

Question 3

What are the types of cataract?

Answer 3

• Involutional  age-related – most common type
• Congenital
• Traumatic
• Secondary – px taking steroids

Question 3

How much of global blindness is due to cataract?

Answer 3

40% of global blindness due to cataracts – approx. 16 million
Increasing every year
Age related condition

Question 4

Classifying type of cataract based on location of opacity?

Answer 4

• Most cataracts are nuclear cataracts
• Cortical cataract:
  o Peripheral lens fibres are less compact & more loose – can get opacified as evolutional change
• Posterior subcapsular – just under posterior capsule – typically seen in steroid users & diabetics
  o Ground glass opacification
• Christmas tree:
  o Not as commonly seen
  o More often seen in involutional/age-related or diabetic pxs
  o Myotonic dystrophy can lead to seeing this earlier in life – congenital disease where muscles are affected
• Congenital:
  o Urgent referral to local HES – can be very serious cataract
• Posterior Polar:
  o Thought to be developed at birth or in younger yrs of life
  o Manifested later in life
  o Can cause complications during cataract surgery – opacification is in posterior capsule and while removing lens that can cause a posterior capsular tear (cataract surgery complication)
  o Surgeon needs to know about this – as different technique can be used to remove the cataract to try and avoid the complication of tear

Question 5

What are the 5 stages of cataract surgery (before and after)? - the process to achieve optimal vision in cataract px

Answer 5

Clinical assessment
Preop assessment
Removal of cataract
Insert intraocular lens (IOL)
Visual aids if needed (approx 4 weeks)

Question 6

Describe clinical assessment before cataract surgery?

Answer 6

• Visual acuity
• Refraction
• History:
  o Visual needs
   6/18 px who is non-driver & does not read much may not need cataract surgery
   6/6 px with posterior subcapsular cataract may have disabling glare while driving for work
  o Symptoms - reduced VA, glare, monocular diplopia
  o Change in refraction- myopic shift or astigmatism
  o Systemic drugs: Alpha antagonists -tamsulosin
   Can affect pupil dilation – surgeon may need extra steps to dilate the pupil (e.g. ring or hook)

Question 7

Desccribe the preop assessment before cataract surgery?

Answer 7

• Examination :
  o Lie flat- spinal abnormalities, COPD
   Can they lie flat for about 30mins?
   These pxs would likely not be put on a hugh volume cataract surgery list
  o Deep set eyes
   Can affect where surgeon accesses eye to perform surgery – usually superiorly but can be temporally if deep set eyes
  o Lids- Blepharitis, malposition (ectropion, entropion)
   These need treated first before going for surgery
   Blepharitis – lid inflammation, red eye
   All 3 can lead to intraocular infection
  o Cornea: Fuchs’ endothelial dustrophy
   Beaten metal appearance – Guttata – endothelial corneal cells are genetically programmed to die at a higher rate than normal – pxs lose more cells than normal
   Later stage – corneal oedema
   Surgeon may need to use a different technique to protect endothelium
  o Adequate pupil dilation
   Poor pupil dilation:
• Age related
• Alpha 1 blocker
• Diabetic
• Uvetic posterior synechiae
• Pseudoexfoliation – cause poor pupillary dilation – pupil fails to dilate – operation can be difficult
  o Type of cataract
   Is it a wide cataract – does surgeon need to take extra precautions/steps for this cataract? Will the usual time slot be enough or does it need more time allocated to it?
  o Fundus - Macular degeneration, retinal detachment

Question 8

Describe optical biometry (cataract surgery)?

Answer 8

• For selection of correct IOL power
  o Corneal power (keratometry)
  o Axial length
  o Constants – specific for the lens the surgeon uses
• Ultrasound
  o About 1/3 cannot be measured using optical – infrared rays do not penetrate dense cataract to determine power or in cases where px cannot sit in the chair for the optical method – so ultrasound must be used in these cases
  o Error prone – use probe and needs to be vertical with anterior surface of cornea – if px moves eyes a lot then this could be very difficult
• Optical
  o Keratometry
  o 6-32 points on cornea
  o 2.3mm of central cornea
  o Uses infrared rays
• Optical more accurate than ultrasound so is default method
• SNR – signal noise ratio should be as high as possible
  o Can get inaccurate axial length readings which can have impact on IOL power calculation and then ultimate vision level px can achieve

Question 9

What are the types of cataract surgery?

Answer 9

• (Intracapsular) Historical – no longer done
• Extra capsular cataract extraction (ECCE) – used to be common method – make big incision on superior limbus (see image)
• Phacoemulsification – method of choice now – small incision or keyhole surgery
• Laser assisted cataract extraction – gaining popularity (especially privately)

Question 10

What is the IOL?

Answer 10

PMMA
Aspheric design IOL
Most common is multifocal lens
Using more toric lens – may see mark indicating this on lens (used in astigmatism over 2/3D with regular corneal astigmatism)
Multifocal IOL – concentric rings on lens

Question 11

Describe phacoemulsification?

Answer 11

Incision made at limbus – 2.8mm
Anterior capsule is torn
Controlled fashion
Usually done under red reflex
Stain capsule blue then tear 6mm of anterior capsule
Use ultrasound probe to emulsify nucleus (most compact part of lens) by dividing lens into 4 parts
Then irrigate and aspiration  then insert IOL (folded acrylic lens – unfolds in eye)

Clear corneal incision
Capsulorhexis
Phaco of nucleus
Irrigation & aspiration
Insertion of IOL

Question 12

Describe the visual outcome of cataract surgery?

Answer 12

• BCVA- 90% >/= 6/12 within 3 months
• > 80% within predicted refraction

Question 13

What are the intraoperative complications?

Answer 13

• Posterior capsular tear 2%
• Nucleus drop 0.5%
• Zonular dehiscence

Question 14

Describe post-operative treatment?

Answer 14

• Topical steroids (dexamethasone 0.1% or Prednisolone 1%) qds x 4 weeks
• Topical antibiotics – (chloramphenicol) qds x 4 weeks
• (Topical NSAID – if diabetic)

Question 15

Describe cystoid macular oedema after cataract surgery?

Answer 15

• Cysts in macular area
• Pre-disposition to CMO: may want to treat with steroids at time of operation in these pxs due to CMO
  o Diabetes – pre or proliferative
  o AMD- dry – thought that RPE cells in this condition lose ability to drain fluid away
  o Previous eye CMO
  o Prostaglandin analogue – glauc pxs
  o Epiretinal membrane – degenerative condition of top layer of retina
  o Complicated cataract surgery
  o Anterior chamber IOL – sometimes unable to put lens in anterior capsule and have to put it in front of iris
• Treatment:
  o Acular (NSAID) tds 1 month
  o Predforte/Maxidex (Dexamethasone, Prednisolone) qid 1 month
  o Subtenon steroids
  o Intra vitreal steroids

Question 16

Describe corneal oedema after cataract surgery?

Answer 16

• Dense cataract
  o Ultrasound power is great – which can damage endothelium cells (which job it is to remove water from cornea – so oedema may not clear)
• Fuchs endothelial dystrophy
• Surgical trauma
• Treatment:
  o Maxidex/predforte 4 times
  o May need lamellar corneal transplant if meds don’t work to clear it

Question 17

Describe double vision after cataract surgery?

Answer 17

• Unmasking of phoria – self limiting
• Rule out unrelated new neurological event e.g. 3rd NP or 6th NP (urgent referral)
• Needs orthoptic assessment

Question 18

Describe raised IOP following cataract surgery?

Answer 18

• Retained viscoelastic – immediate post op period, treated medically, paracentesis – at end of surgery this is removed, in some cases may not be fully removed
• Steroid responder – resolve on stopping topical steroids
• Pre-existing glaucoma – cover immediate post op period with oral Acetazolamide

Question 19

Describe retained lens fragment following cataract surgery?

Answer 19

• Rarely
• Retained lens matter will be seen on slit lamp when do post operative check up
• Can be asymptomatic
• Usually have to be removed as can rub on corneal endothelium & cause inflammation as well as corneal decompensation due to damage to endothelial cells
• Px will need a 2nd surgery

Question 20

Describe retinal detachment after cataract surgery?

Answer 20

• 1%
• Floaters, shadow in visual field
• Dilate, retinal exam
  Retinal detachment – rare - ~1% - more common in high myopes – carefully investigate if px reports new floaters

Question 21

Describe dry eye after cataract surgery?

Answer 21

• ‘very common’
• Severity varies
• “will improve”
• Topical lubricants
• Can be associated with age

Question 22

Describe dyphotopsia after cataract surgery?

Answer 22

* Thought to be due to sharp edge of IOL (to prevent posterior capsular opacification) – has led to dysphotopsia when light is incident on lens edge * POSITIVE o Starbursts, haloes, flashes of light, streaks of light * NEGATIVE o Shadow in visual periphery o Dilate and fundus examination – rule out retinal detachment * Reassurance is normally enough

Question 23

What would you do for ptosis and PCO after cataract surgery?

Answer 23

Ptosis – self limiting Posterior capsular opacification – 10% -> YAG Capsulotomy

Question 24

Reasons for refractive surprise following cataract surgery?

Answer 24

* Wrong IOL * Biometry error * Capsule distension * Aqueous misdirection

Question 25

Describe endophthalmitis after cataract surgery?

Answer 25

* Hypopyon * REFER IMMEDIATELY  px will require intraocular antibiotics * V red eye, corneal oedema, whitish material in AC (hypopyon) * 1 in 2000/3000 * Type of intraocular infection reason why blepharitis, ectropion and entropion need treated before cataract surgery carried out

Question 26

Describe post op fibrin in AC afteer cataract surgery?

Answer 26

* REFER IMMEDIATELY * Another type of intraocular infection * Even if this px is treated – level of vision may be quite reduced reason why blepharitis, ectropion and entropion need treated before cataract surgery carried out

Question 27

Describe post op endophthalmitis

Answer 27

* Within 4 weeks * Pain, redness, hypopyon, fibrin, poor vision * Vitreous biopsy and intravitreal antibiotics * Poor prognosis * Prevention: o Treat preop conditions- blepharitis, lid malposition o Betadine prep o Intraoperative antibiotics o Post op antibiotics

Question 28

Describe toric IOL?

Answer 28

* Up to 2D – these are NOT used o If incision is put on axis then that should correct about 1.5-2D * >2D – toric IOL can be considered * No restriction to health board

Question 29

Which systemic condition is associated with Christmas Tree Cataract?

Answer 29

Myotonic dystrophy

Question 30

Why might ultrasound biometry be used to determine ocular biometry prior to cataract surgery?

Answer 30

Because dense cataracts are present

Question 31

Which of following conditions may require surgical correction prior to cataract surgery taking place?

Answer 31

Entropion (other options were strab and chalazion)

Question 32

Which is not a risk factor for CMO development post-op (cataract)?

Answer 32

Topical beta blockers (other options diabetes, ARMD, anterior chamber IOLs)

Question 33

Which of the following is most common cataract procedure in UK currently?

Answer 33

Phacoemulsification (other options intracapsular cataract extraction, extracapsular cataract extraction, laser assisted cataract removal)

Question 34

What is dysphotopsia?

Answer 34

Symptoms resulting from light incident on IOL edge

Question 35

What proportion of pxs who have a cataract operation will develop PCO?

Answer 35

10%

Question 36

Which of following increases risk of retinal detachment following cataract surgery?

Answer 36

Myopia (other options hyperopia, bleph, high blood pressure)

Question 37

Cataract Surgery - what happens?

Answer 37

Clear corneal incision: They make an incision on the cornea so to not damage the ciliary body as precious During cataract surgery – they can tie thread round EOMs to hold the eye still if the eye is going to move a lot Capsulorhexis: Want to preserve lens capsule and leave it and not burst it – just want to remove the nucleus – so can put the new IOL in – thinking of like shopping bag, cannot put your shopping a broken bag Capsulorhexis – this is normal – their capsule will look like this and can often see when dilate the patient Phacoemulsification: Hoover and chopper – ultrasound to suck capsule out Irrigation & Aspiration: Bag can collapse when nucleus removed – so they use lots of fluid to keep it open up so can put new lens in Insertion of IOL: * Usually no sutures * Post-op drop regimen o Antibiotic – taken for 1 week o Anti-inflammatory – taken for 4 weeks  Can expect to see cells and flare straight after surgery as they’ve been into the eye * Px sees optom in 4-6 weeks