Irregular cornea

Question 1

Aims of Refractive surgery

Answer 1

Better unaided vision 
Less reliant on specs/cls 
Enhance sports/performance 
Cosmetics
Self esteem 
Solve cl wear failures

Question 2

LASIK

Laser assisted in-situ keratomileusis

Answer 2

Corneal flap cut with microkeratome 
Laser reshapes exposed stroma 
Replace flap 
Sutures not required
Bowmans layer preserves

Question 3

LASIK complications

Answer 3

Decentred ablation 
Photophobia 
Glare/haloes
Rx issues 
Poor microkeratome cut 
Flap issues

Question 4

PRK

Photo-refractive keratectomy -process

Answer 4

Argon fluorine laser - 193nm
High photon energy breaks monocular bonds
Precise tissue removal
Min thermal damage to adjacent tissue

Question 5

PRK complications

Answer 5

Topo changes - central islands
Decentred ablation
Over/under correction
Rapid regression

Question 6

LASEK

Laser assisted sub-epithelial keratectomy

Answer 6

Combines benefits of lasik/prk
Outer cornea lifted - using numbing drops/alcohol solution /fine blade
Laser reshapes remaining corneal surface
More pain/discomfort > lasik
Less pain < prk

Question 7

Radial keratotomy RK

Answer 7

Myopia reducing surgery
Series deep, mid-peripheral radial incisions
- 4-8, 90% depth
Flatten corneal curvature

Question 8

Rk complications

Answer 8

Corneal perforation 
Incision extended into limbal/optic zone 
Intersecting incisions 
Recurrent corneal erosions
Increased astigmatism 
Reduced BCVA 
Diurnal variations 
Myopic/hyperopic shift

Question 9

INTACS

Answer 9

Mechanical correction device - PMMA 
9-10m diam
Thickness 0.2-0.45mm - dictates refractive effect
Inserted in peripheral stroma 
2/3 corneal depth 
4D myopia limit

Question 10

INTACS indications

Answer 10

16+yo
K<60d
Corneal thickness >400u
Absence of corneal disease 
Flattening steepest k by 1.5-2.5d

Question 11

Complications for INTACS

Answer 11

Peripheral corneal haze poss
Lamellar channel deposits common
Deep stromal vascularisation common
Corneal pannus common

Question 12

Penetrating keratoplasty - PK

Answer 12

Abnormal cornea replaced with healthy donor

Full thickness graft

Question 13

Indications for pk

Answer 13

Cosmetic
Structural
Therapeutic
Optical

Question 14

Early complications PK

Answer 14

Shallow AC
Iris prolapse 
Persistent epithelial defects 
Infection 
Primary graft failure 
Wound leak 
Increased IOP

Question 15

Later complications pk

Answer 15

Astigmatism 
Glaucoma 
Cataract 
Graft failure/rejection
Graft infiltrates 
Recurring corneal issues

Question 16

Graft rejection

Answer 16

Most common in PK 
Risk greatest in 1st yr
Assoc with glaucoma 
RSVP 
- redness 
- sensitivity to Light
Vision drop
Pain

Question 17

DALK

Deep anterior lamellar keratoplasty

Answer 17

Lamellar graft
Treat corneal disease upto endothelium
- KC/stromal scars/some corneal dystrophies
Requires sutures
Unpredictable refractive outcome - irregular astigmatism/anisometropia

Question 18

DALK pros

Answer 18

Faster wound recovery
Faster visual rehab
Fewer wound related issues
Better preserves ocular integrity 
Earlier suture removal

Question 19

Endothelial keratoplasty EK

Answer 19

Endothelial disorders

- Fuchs / bullous keratopathy

Question 20

EK process

Answer 20

Diseased DM/endothelium stripped
Donor tissue transferred to AC
Donor tissue unfolded - attached to posterior stroma using air bubble
Sutureless

Question 21

EK pros

Answer 21

Sutureless - avoid suture issues
Preserves structural integrity 
Reduced wound healing issues 
Major refractive changes avoided 
Rapid healing

Question 22

EK cons

Answer 22

Anterior corneal irregularities -> reduced va 
Anterior stromal collagen disruption 
Reduced BCVA 
Monocular diplopia/ghost images
Sub-epithelial fibrosis (diffusive)