AED - Cataracts II & III- PAP Week 1 Flashcards
What are the three types of senile cataracts?
Nuclear
Cortical
Posterior subcapsular
Does smoking increase or decrease the risk of senile cataract? Which types (2)?
Increases risk of nuclear/cortical cataracts
What is the most common form of senile cataracts?
Nuclear
How does senile cataracts appear and what is a possible casue?
Appears like a yellow haze in the nucleus and posterior cortex
Possible cause is light damage to the lens proteins
What are 4 visual symptoms of senile cataracts?
Glare
Light loss
Polyopia
Blur
What refractive shift may occur with cataracts? What is indicative of nuclear sclerosis?
Myopic shift
-1.00D/4 years is indicative of nuclear sclerosis
Why may mydriasis improve vision in those with cataracts?
Light may bypass the cataract
Why may some hyperopes find their vision improving when they have cataracts?
The myopic shift caused by the cataract may correct their hyperopia
What is the appearance of cuneiform cortical cataract and what causes this?
Wedges/spokes
Due to water accumulation between fibres, possibly due to UVB
Is cuneiform cortical cataract central or peripheral and what effect does it have on vision?
Peripheral location, minor effect on vision
Does cuneiform cortical cataract cause hyperopic or myopic shift?
Hyperopic
What happens to the lens itself in cuneiform cortical cataract (aside from its appearance)? What can it result in?
Lens growth causing swelling - intumescence
Possible pupil block
How does cuneiform cortical cataract progression appear (2)?
By expansion and coaslescing of spokes
Does miosis or mydriasis improve VA in cuneiform cortical cataract?
Miosis
What is the least common form of senile cataract?
Posterior subcapsular
What makes posterior subcapsular cataracts visually the most debilitating?
Its location
Does miosis or mydriasis improve VA in posterior subcapsular cataract?
Neither
What is the cause of age-related posterior subcapsular cataract?
Thinning of the posterior capsule resulting in greater H2O influx
What causes the lacey apeparance of the posterior subcapsular cataract opacity?
Migration of bow cells
What medication can cause posterior subcapsular cataract?
Corticosteroids
What are three possible consequences of cataracts over time (consider the lens swelling)?
Glaucoma
Pupil block
Uveitis due to capsular rupture
What is the most common cataract intervention? What else can be done and why is it generally done (neonates)? What kinds of cataracts specifically is this done to (2) and in what age group?
Surgery with aphakia/pseudophakia
Dilate neonates with homatropine for nuclear or anterior capsular (but not posterior subcapsular)
Done to prevent amblyopia onset
Why can surgical intervention for cataracts often be delayed?
It has few ocular complications
When should surgical intervention be undertaken with cataracts (3)?
If eye complications occur
It impedes lifestyle or work (jeweller/gardener)
Driving - legal status is 6/12
Is it better to wait for a cataract to be hypermature before surgical intervention?
No, it complicates the surgery
What are three considerations when communcating to a patient about cataracts?
Age - child vs adult
-amblyopia prevention
-referral for secondary systemic disorder
Patient overall health
Patient communication
-preparing the patient
-breaking the bad news
-consequence/prognosis
When recommending surgical intervention for cataracts, what considerations should be given to the patient for the benefits (4), complications (2), and expectations of the surgery?
Likely benefits are
-improved VA
-less glare and polyopia
-better colour vision
Possible complications are:
-~1% have unsuccessful outcomes
-light/glare sensitive for up 3-6 months after surgery in 20-40%
Expectations of the surgery - if 6/6+ vision is expected by the patient, this is unrealistic
In some cases, the reported disability may be inconsistent with the relatively good VA (6/9) in cataracts. Explain why this may happen (2).
Possibly due to low contrast VA and glare sensitivity
List the two ways of glare testing. Note the most common.
Brightness acuity tester
Pen torch - most common
Describe the brightness acuity tester.
An illuminated spherical bowl where the patient looks out a hole in the middle and VA is measured, with and without background light.
Describe how a pen torch can be used to assess glare.
Have the torch near the nose, pointing into the pupil like a car headlamp and measure VA
The health of what part of the eye (aside from the lens) can give a poor prognosis for cataract surgery (2)?
Poor macular/optic nerve function
List 7 ways macula function can be assessed.
Colour discrimination (crude)
High/low CS VA
Low illuminance VA
PAM/laser interferometer
Multifocal ERG
B-scan for dense cataract
OCT
List 4 ways optic nerve function can be assessed.
Afferent pupillary defect
Visually evoked response
LC/HC loss
Low illuminance VA
-loss of >5 lines = disease
List and describe two historical surgical procedures for cataract removal.
Couching - lens physically pushed back
Needling - rupture of the capsule with a fine needle
List the two types of modern surgical procedures for cataract removal.
Intra capsular cataract extraction
-takes the lot
Extra capsular cataract extraction
-leaves the lens capsule
Is intra capsular cataract extraction common?
No, its rare
Describe how intra capsular cataract extraction is done. What injection is needed and why?
Large cut is made superiorly and a a-chromotrypsin injection is needed to break zonules
List two disadvantages of intra capsular cataract extraction.
Requires a large surgical cut
No bag to carry an IOL
What can an anterior IOL / no lens facilitate (2)?
Vitreous prolapse and retinal detachment
Define capsulorhehexis.
When the anterior lens capsule is torn for surgery
Define phakoemulsification.
Using a high speed agitator (40Hz) that disrupts the lens
When closing a surgical incision made during cataract surgery, what can sutures induce, and why?
It can pull on the cornea, increasing curvature, resulting in astigmatism
How should eye sutures be removed?
Cut with 25g needle and pull large part away from the eye
Do not pull into the eye
Does extra capsular cataract extraction require sutures?
Usually no
List 2 complications of sutures.
Can cause giant papillary conjunctivitis
Can leak - use NaFl
What is a consideration for sutures with high astigmatism?
Consider removing after 3 months to be sure of stability
What power change does aphakia induce?
10-12D of hyperopia
Can contact lenses be used to treat aphakia?
Acceptable alternative as spectacles may cause jack-in-the-box effect
List the two types of IOLs.
Anterior chamber - iris/AC angle fixed
Posterior chamber - in the capsule
What is an important property that IOLs should have and why?
UV block to protect the retina
Describe a pars plana lensectomy. What may it invole?
Lens removal approach from behind the lens
May invole a vitrecomy
List four complications of cataract surgery and their consequences if applicable (2).
Capsular tear/rupture
-nucleus drops into the vitreous
Zonular breaks
-lens drops into the vitreous
Iris damage
Wound leak
What are three ways presbyopia can be managed following cataract surgery?
Monovision
-OK for low adds, high adds can induce supression
Reading glasses
Multifocal IOLs
What are two post surgical drops following cataract surgery and what is the schedule like?
Topical antibiotic
-chloramphenicol (most common)
-fluoroquinolone
-qid for 1/52
Topical steroid
-prednisolone forte (most common)
-dexmethasone
-qid week 1, tid week 2, bd week 3, qd week 4
What is the followup schedule for cataract surgery (6)?
1 day
1 week
3 weeks
6 weeks
12 weeks
1 year
What are 5 late post surgical complications following cataract surgery?
Suture exposure
Sutural astigmatism
Dysphotopsia
Cystoid macular oedema
Capsular opacification
