Soft lens fitting

Question 1

What are the indicators of a good fit?

Answer 1

Comfortable
Good, stable VA, effected minimally by blink
Good coverage on excursions
Good centration

Question 2

What will vision be like after a blink if a lens is too tight?

Answer 2

Better

Question 3

What will vision be like after a blink if a lens is too loose?

Answer 3

Worse (lens moved by blink)

Question 4

What features of a lens influence the fit?

Answer 4

BC
Sag
Design and material
Edge and centre thickness
Water content
Modulus

Question 5

What ocular factors affect lens fit?

Answer 5

HVID
VPA
Sag of cornea
Corneal apex
Upper lid angle
Lid pressure
Tear film

Question 6

What can affect comfort, excluding fit?

Answer 6

FB under lens
Pre-existing ocular condition
Tear film quality
Insertion technique
Lens thickness/modulus
Lacrimation
Differences in corneal sensitivity

Question 7

How much lag is optimum?

Answer 7

0.5-1mm

Question 8

How much movement on blink is optimum?

Answer 8

~0.25-0.5mm

Question 9

What does an optimum push up test look like?

Answer 9

easy to move, quick recovery to original position

Question 10

If a lens is too tight, how can you amend the fit?

Answer 10

Try another manufacturer
If J&J, increase BC

Question 11

If a lens is too loose, how can you amend the fit?

Answer 11

Try another manufacturer
If J&J, reduce BC