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SCOT > Cataract > Flashcards

Cataract Flashcards

1
Q

Where does the lens sit?

A

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)

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2
Q

What is the function of human lens?

A
  • Refractive
    o One third of optical power (approx. 18-20D out of 60D)
    o Rest of refractive power by cornea
  • Accommodation
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3
Q

What is the pathogenesis of cataract?

A
  • 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
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3
Q

What are the risk factors of cataract?

A
  • 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
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3
Q

What are the types of cataract?

A
  • Involutional  age-related – most common type
  • Congenital
  • Traumatic
  • Secondary – px taking steroids
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3
Q

How much of global blindness is due to cataract?

A

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

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4
Q

Classifying type of cataract based on location of opacity?

A
  • 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
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5
Q

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

A

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

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6
Q

Describe clinical assessment before cataract surgery?

A
  • 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)
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7
Q

Desccribe the preop assessment before cataract surgery?

A
  • 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
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8
Q

Describe optical biometry (cataract surgery)?

A
  • 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
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9
Q

What are the types of cataract surgery?

A
  • (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)
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10
Q

What is the IOL?

A

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

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11
Q

Describe phacoemulsification?

A

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

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12
Q

Describe the visual outcome of cataract surgery?

A
  • BCVA- 90% >/= 6/12 within 3 months
  • > 80% within predicted refraction
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13
Q

What are the intraoperative complications?

A
  • Posterior capsular tear 2%
  • Nucleus drop 0.5%
  • Zonular dehiscence
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14
Q

Describe post-operative treatment?

A
  • Topical steroids (dexamethasone 0.1% or Prednisolone 1%) qds x 4 weeks
  • Topical antibiotics – (chloramphenicol) qds x 4 weeks
  • (Topical NSAID – if diabetic)
15
Q

Describe cystoid macular oedema after cataract surgery?

A
  • 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
16
Q

Describe corneal oedema after cataract surgery?

A
  • 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
17
Q

Describe double vision after cataract surgery?

A
  • Unmasking of phoria – self limiting
  • Rule out unrelated new neurological event e.g. 3rd NP or 6th NP (urgent referral)
  • Needs orthoptic assessment
18
Q

Describe raised IOP following cataract surgery?

A
  • 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
19
Q

Describe retained lens fragment following cataract surgery?

A
  • 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
20
Q

Describe retinal detachment after cataract surgery?

A
  • 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
21
Q

Describe dry eye after cataract surgery?

A
  • ‘very common’
  • Severity varies
  • “will improve”
  • Topical lubricants
  • Can be associated with age
22
Q

Describe dyphotopsia after cataract surgery?

A
  • 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
23
Q

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

A

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

24
Q

Reasons for refractive surprise following cataract surgery?

A
  • Wrong IOL
  • Biometry error
  • Capsule distension
  • Aqueous misdirection
25
Q

Describe endophthalmitis after cataract surgery?

A
  • 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
26
Q

Describe post op fibrin in AC afteer cataract surgery?

A
  • 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
27
Q

Describe post op endophthalmitis

A
  • 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
28
Q

Describe toric IOL?

A
  • 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
29
Q

Which systemic condition is associated with Christmas Tree Cataract?

A

Myotonic dystrophy

30
Q

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

A

Because dense cataracts are present

31
Q

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

A

Entropion (other options were strab and chalazion)

32
Q

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

A

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

33
Q

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

A

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

34
Q

What is dysphotopsia?

A

Symptoms resulting from light incident on IOL edge

35
Q

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

A

10%

36
Q

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

A

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

37
Q

Cataract Surgery - what happens?

A

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

SCOT (23 decks)

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