Week 7 - Corneoscleral Lenses

Question 1

What are Corneoscleral lenses?

Answer 1

• Vision correction of GP
• Comfort of Soft
• Low Cost same as GPs
• Easy handling
• Patients love them!!

Question 2

Definition of scleral corneal lens and corneal scleral lens?

Answer 2

• Touches eye only on sclera, and involk (not touches) cornea
• Touches the cornea and sclera both

Question 3

What is a corneal scleral lens alignment?

Answer 3

• Central zone: Aligns with cornea
• Lenses should never bear on limbus

Question 4

How does a stepper lens affect the tear film vs flatter lens?

Answer 4

• Larger tear lens therefore makes a plus tear lens
• Flatter lens results in a negative tear lens

Question 5

What is a Flat fit?

Answer 5

• Flat fit
- Central zone: Too flat, steepen BOZR by 0.2
- “Hard touch” at limbus sharp demarcation

Question 6

What is a steep fit?

Answer 6

• Central Zone: Too steep, flatten BOZR by 0.2
• NaFl should be visible over limbus - isn’t in steep feet

Question 7

What is an optimum fit?

Answer 7

• Central Alignment
• Edge Lift
- Min - Tear Pump with FL
- Max - Comfort
• Limbal Clearance
• Immediate comfort

Question 8

How are corneoscleral lenses fitted and how are edge lift assessed?

Answer 8

• Unlike corneal GP, NO anaesthetic for fitting
• NaF in eve after lens
• NaF under lens shows either adequate or large edge lift
• Comfort <7/10 edge too large or very sensitive patient.

Question 9

How is Toric Over-Refraction done?

Answer 9

• Note axis marks on CL
- Rotationally stable
- Aligns with Ks (+20deg)
• If rotationally unstable, Alter BOZR to improve fit

• -ve cyl aligned with axis marks on lens
• Sphere is added on both flat and steep axis

Question 10

How are corneoscleral lenses put in and removed?

Answer 10

• Drops in CLs, placed directly on eye over cornea+ slera
• Removal:
- sucker or RGP lenses

Question 11

What are adverse side effects of corneoscleral lenses? (greasing)

Answer 11

• Greasing
• Large area of ‘plastic’ like a SCL
• Dry eye lipid deposition
- solve with Part time wear

Question 12

What are adverse side effects of corneoscleral lenses? (tear reservoir )

Answer 12

• Tear reservoir debris
• More common in keratoconic fits with steep apex
- Solve with Flatten BOZR

Question 13

What are adverse side effects of corneoscleral lenses? (Adverse conditions)

Answer 13

• Solution reaction
• Less tear pump the corneal GPs
• Use PF drops for insertion