Week 16 - Cataracts

Question 1

Human lens - function

Answer 1

• Refractive
one third of optical power (approx. 20 D out of 60D)
• Accommodation

Question 2

Cataract - pathogensis

Answer 2

• Protein denaturation
• Oxidative damage

Question 3

Cataracts - Risks

Answer 3

•Age
•Smoking
• Alcohol
• Dehydration
•Radiation
• Diabetic
•Steroids

Question 4

Cataract prevalence:

Answer 4

• 40% of global blindness
• Approx: 16 million

Question 5

Cataracts - Categories

Answer 5

• Involutional
• Congenital
• Traumatic
• Secondary

Question 6

Cataract - types

Answer 6

• Nuclear
• Cortical
• Posterior subcapsular
• Christmas tree cataract
• Congenutal cataract
• Posterior polar cataract

Question 7

Cataract surgery process:

Answer 7

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

Question 8

Clinical assessment during cataract:

Answer 8

• Visual acuity
• Refraction
• History:
- Visual needs
- Symptoms: reduced VA, glare, monocular diplopia
- Change in Rx: Myopic shift or astigmatism
- Systemic drugs: Alpha antagonists - tamsulosin

Question 9

Preop assessment: Examination

Answer 9

• Make sure lie flat - spinal abnormalities
• Deep set eyes
• Lids - blepharitis, malposition
• Cornea: Fuchs’ endothelial dystrophy
• Adequate pupil dilation
• Type of cataract
• Fundus - Macular degen, retinal detachment

Question 10

Poor pupil dilation causes:

Answer 10

• Age related
• Alpha 1 blocker
- Prazasin
- Terazosin
- Doxazosin
• Diabetic
• Uvetic posterior synechiae

Question 11

Ocular Biometry:

Answer 11

• For selection of correct IOL power
• Ultrasound
• Optixal

Measures:
• Corneal power (keratometry)
• Axial length
• Constants

Question 12

Optical biometry- keratometry

Answer 12

• 6-32 points on the cornea
• 2.3mm of central cornea

Question 13

Types of cataract surgery:

Answer 13

• (Intracapsular) Historical
• Extra capsular cataract extraction (ECCE)
• Phacoemulsification
• Laser assisted cataract extraction

Question 14

IOP types: Materials

Answer 14

• Rigid: PMMA
- Disadvantage : larger incision needed
• Foldable: Silicone
- Silicone oil adheres
• Acrylic:
- Hydrophobic: Adv - Low PCO
- Hydrophobic: Adv - Low inflamatory cell attachment

Question 15

Phacoemulsification process:

Answer 15

• Clear corneal incision
• Capsulorrhexis
• Phaco of nucleus
• Insertion of IOL
• Irrigation & aspiration

Question 16

Intraoperative complications

Answer 16

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

Question 17

Alternative IOL’s:

Answer 17

• Anterior chamber IOL

Question 18

Post-Operative treatment

Answer 18

• Topical steroids (dexamethasone 0.1% or
Prednisolone 1%) qds x 4 weeks

• Topical antibiotics - (chloramphenicol) qds x 4 weeks

• (Topical NSAID - if diabetic)

Question 19

Visual outcomes post surgery:

Answer 19

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

Question 20

Cystoid macular oedema (CMO): Risks

Answer 20

• Diabetes
• AMD - dry
• Previous eye CMO
• Prostaglandin analogues
• Epiretinal membrane
• Complicated cataract surgery
• Anterior chamber IOL

Question 21

CMO : Treatment

Answer 21

• Acular (NSAID) tds 1 month
• Predforte/Maxidex (Dexamethasone,
Prednisolone) qid 1 month
- Subtenon steroids
- Intra vitreal steroids

Question 22

Corneal oedema: cause

Answer 22

• Dense cataract
• Fuchs endothelial dystrophy
• Surgical trauma

Treat: Maxidex/predforte 4 times

Question 23

Double vision:

Answer 23

• Unmasking of phoria - self limiting
• Unrelated new neurological event
• Needs orthoptic assessment

Question 24

Raised IOP:

Answer 24

• Retained viscoelastic - immediate post op period, treated medically, paracentesis
• Steroid responder - resolve on stopping topical steroids
• Pre-existing glaucoma - cover immediate post op period with oral Acetazolamide

Question 25

Surgical complications

Answer 25

• Lens fragments in anterior chamber • Seidle sign • Retinal detachment - 1% - Floaters, shadow in visual field - Dilate, retinal exam • Dry eye - Common, severity varies, topical lubricants • Dysphotopisa - Positive: starbursts, haloes, flashes of light - Negative: shadow in visual periphery • Dilate and fundus exam? • Ptosis: self limiting • Posterior capsular opacification - 10%; treat with YAG capsulotomy

Question 26

Refractive surprise:

Answer 26

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

Question 27

Severe complications:

Answer 27

• Endopthalmitis - c hypopyon - REFER IMMEDIATELY • Post op fibrin in AC - refer immediately

Question 28

Postop Endophthalmitis:

Answer 28

• Within 4 weeks •Pain, redness, hypopyon, fibrin, poor vision • Vitreous biopsy and intravitreal antibiotics • Poor prognosis

Question 29

Prevention of complications

Answer 29

• Treat preop conditions- blepharitis, lid malposition • Betadine prep • Intraoperative antibiotics • Post op antibiotics