Fitting Irregular cornea Flashcards
Requirements of cl
Preserve integrity of corneal epithelium
Sufficient o2 to susceptible cornea
Protrusion graft
Donor too large for recipient
Proud graft
Host cornea too thin @junction - shelf
Sunken graft
Donor same size graft - easy fit
Tilted graft
Variations in margin thickness/suture depth
Can -> decentred cl
Eccentric graft
Centred on thin /scarred corneal area
Increases complications
Post PK cl fit
GP cls:
- large TD (9.5-12mm)
- central vaulting
- fenestrations if needed
Reverse geometry - SCLs Sutures still in place Customised toric design Piggyback fit - low power - high dk/t
Post graft fit
Graft may b tilted
BOZD»graft - avoid abrading scarred areasa
Flex lens
Piggy back lens
1mm flatter than flattest k
1-1.5 limbal draping
GP cl diam 1mm smaller than anterior cut out boundaries - facilitate cl movement/tear exchange
Keratonic fitting principles
Apical bearing - increases apical scarring
3 point touch
Apical clearance - best choice
KC fit considerations
Cone size /position/shape
Corneal toricity
Corneal e value
PMD
2 cones
SCLERAL best option
Collagen cross linking process
Topical riboflavin drops 30mins
UV 30mins
Bandage cl 5 days after
No cl wear 3-4months post op - allow keratocyte regeneration
CXL
Decrease keratocytes in anterior stroma - repopulates over next 3-9months
Expect 1-2D diff in ks
Attempt to age cornea not cure - vision may decrease
Contraindications for CXL
Stromal thickness <400u
Corneal scarring
H/o kernes keratitis
