3. Cataracts 3

Question 1

What are the two older cataract surgery techniques?

Answer 1

• Couching
• Needling

Answer 2

Couching
* pushing backwards of lens (surgical subluxation)
* may be used in 3rd world (Arabia, Africa)
* Complications: need aphakic correction; glaucoma, uveitis, optic atrophy.

Answer 4

Needling
* useful for soft/ young cataracts
* rupture of capsule with fine needle
* Complication: foreign material can produce an inflammatory response
* Limited application in adults

Question 5

What are the 2 types of lens extraction techniques? What are their differences?

Answer 5

• Intracapsular cataract extraction (ICCE) → breaks zonule, take lens out
• Extracapsular cataract extraction (ECCE) → leaves the capsule & only take out the contents of the lens; conventional expression (hard lens) or phakoemulsification (phako)

Question 6

What are the 4 main types of ocular anaesthetics? What technique uses which?

Answer 6

• General (ICCE) → rare
• Local (ICCE & ECCE) → retrobulbar or peribulbar
• Topical (phaco) → alcaine drops
• Topical & intraocular mydriatics

Answer 7

IntraCapsular Cataract Extraction ICCE process
1. Large cut made superiorly (4-6 o'clock)
2. Injection of ` α-chromotrypsin to break the zonules 3. Lens removal via cryoprobe/ forceps`

Disadvantages:
* requires a large surgical cut (12-20mm)
* No capsule/ bag to carry the IOL → anterior chamber IOL; can cause vitreous prolapse and retinal detachment due to lack to structure in front of the vitreous.

Answer 8

ExtraCapsular Cataract Extraction ECCE process
* requires a smaller cut (3-5mm)
* retains a normal vitreous ∴ less prone to retinal detachment
* anterior capsule is torn via capsulorhexis
* mechanical removal of lens material, leaving the capsule behind
* Phacoemulsification to divide and conquer the lens

Question 9

What is phacoemulsification?

Answer 9

A phako is a high speed agitator at 40kHz that help divide the len into 4 parts (divide & conquer). Afterwards a suction device helps vacuum up the cortex. This is therefore also called a “jack hammer with vacuum cleaner”

Question 10

What is the disadvantage of wound closure with sutures after ECCE and ICCE surgery?

Answer 10

• Cut will reduce corneal curvature
• Sutures can pull on cornea which increaes curvature and therefore creates astigmatism
• Incision causes ATR (90º)
• Tight suture causes WTR (180º)
• ∴ req balance between suture and incision

Question 11

Which type of cataract sx can utilise sutureless wound closure? How is this done?

Answer 11

ECCE only
* Induce oedema of the cornea. Swelling of the cornea pushes the incision close
* However there is no control of resultant astigmatism

Question 12

What are the 3 cataract surgery complications commonly caused by sutures?

Answer 12

• Suture irritation → GPC
• Tight suture → high astigmatism (>2.5D) → consider removal of sutures after 3 months
• Leakage → Siedel test for NaFl streaming

Question 13

How much dioptres of vision is induced by aphakia?

Answer 13

10-12D hypermetropia

Question 14

What are the 3 correction methods for aphakia?

Answer 14

• Spectacles - least preferred
  ∵ reduced FOV, large magnification, prismatic effect, BV problems & aniesokonia if uniocular
• CL - extended wear
• IOL - most preferred
  → use A-scan, refraction & corneal power to determine IOL power (plastic nowadays)

Question 15

What are the 2 components in an intraocular lens implant?

Answer 15

• Optic
• Haptics

Question 16

What are the 3 types of IOLs?

Answer 16

Anterior chamber → get tissue chaffing ∴ only used if zonules are broken/ weak
* Iris fixed
* AC angle fixed

Posterior chamber
* in the bag/ capsule = best location & optics
* sutured in the sulcus

Question 17

What are the 4 different IOL designs?

Answer 17

• Single vision/ Astigmatic
• Multifocal/ simultaneous focus
• Extended focus
• Movable IOL

Question 18

What is pars plana lensectomy?

Answer 18

• A cataract sx approach from behind the iris.
• Incision is made behind the limbus thorugh the sclera
• This requires general anaesthetic
• May involve vitrectomy
• reserved for complicated cases e.g. ECCE complication, trauma, congenital cataract, diabetic

Question 19

What is the role of a Femtosecond Laser in cataract surgery? What are the benefits (2) and disadvantage (1) of this?

Answer 19

Femtosecond Laser can be used to make the incision, create capsulorhexis and “divide & conquer” the nucleus
Adv: better centration of capsulorhexis; require less energy from phaco
Disadv: surgery is more expensive

Question 20

What are the 4 general surgical complications of cataract sx?

Answer 20

• Capsular tear/ rupture → nucleus drops into vitreous
• Zonular breaks → drop lens into vitreous
• Iris damage
• Wound leak → Seidel’s sign ∴ may req sutures

Question 21

How can presbyopia be managed with or after cataract sx? (3)

Answer 21

• Monovision IOL → suitable for low adds up to +1.50DS; high add may induce suppression
• Multifocal IOL
• Use of reading glasses + Distance SV IOL

Question 22

What are the post surgical drops regime after cataract sx?

Answer 22

• Topical antibiotics → chloremphenicol or fluoroquinolone QID 1/52
• Topical steroids → Prednisolone forte or dexamethazone QID 1/52, TID week 2, BID week 3, QD week 4

Question 23

What is the followup schedule post cataract sx?

Answer 23

1d, 7d, 21d, 6wks, 12wks, yearly

Question 24

What are the 9 common early (<1 month) complications of cataract sx?

Answer 24

• Ptosis w/ local injection (12-15% but reduces by 4 wks)
• Pupillary block with ICCE (vitreous, YAG)
• Wound leak (Seidel, low IOP)
• Toxic Anterior Segment Syndrome (TASS)
• Endophthalmitis (<0.05%)
• Perceived glare arcs or haloes → dysphotopsia
• Anterior chamber debris
• Corneal striae - Bullous keratopathy
• IOL displacement

Question 25

What are the 7 late complications post cataract sx?

Answer 25

• Suture exposure
• Sutural astigmatism
• Dysphotopsia
• Cystoid Macular Edema (CME)
• Capsular opacification
• Bullous keratopathy
• Glaucoma

Question 26

How is posterior capsule opacification managed post cataract sx?

Answer 26

Lasering a hole in the posterior capsule using YAG laser