SCL fitting

Question 1

Steps in selecting a lens

Answer 1

1. Decision on modality
2. O2 & water content considerations
3. Decision on material
4. choose starting lens
5. look at available Rx + cost
6. Manufactures guide for fitting

Question 2

1. Modality of wear consideration

Answer 2

Occasional (3hrs, 2/7)
- dailies

Work (9hrs, 5/7)
- monthlies

F/T wear at work, but non compliance
- dailies

Full time (16hrs, 6/7)
- fortnightly / monthly

Slit lamp –> hypoxia/previous pathology

Question 3

2. O2 & H20 content considerations

Answer 3

O2
- increased WT = increased O2 transmission

H2O content
- if lens drying up = increasing H2O content draws out H2O

Question 4

3. Decision on material

Answer 4

• hydrogen/silicone hydrogel
• Rx range
• cost

Question 5

4. process of choosing starting lens

Answer 5

BOZR calc
- flattest K x 1.1
- fit slightly flatter than flattest K

Adjusting Rx for BOZR
- K=F/(1-dF)
- F=Rx d=BVD (in metres)

Use topic lenses when = cyl > 1.00D

Question 6

Steps for inserting SCL

Answer 6

• px head against chair, facing up
• lower bottom lid, px looks away
• place lens onto conj, keep holdings lids, px looks left/right/up/down
• massage top lid if air bubbles

Question 7

Steps for removing SCL

Answer 7

• same eyelid control
• px looks away
• slide SCL off cornea
• pinch off the conj
• perform health check

Question 8

What to record for fitting

Answer 8

• coverage
• centration
• movement on blink
• comfort
• lag
• sag
• push up
• tightness

Question 9

Why does lens need to fit well

Answer 9

• comfort
• corneal coverage
• good centration
• movement on blink
• optimal tightness
• stable vision

Question 10

Characteristics of a steep fit vs flat fit

Answer 10

steep = minimal lens movement
flat = increased movement

steep = reduced gimbal crossing
flat = poor contraption

steep = vision improves immediately post blink
flat = variable vision

steep = conj identification + redness

flat = buckling at lens edge + lens awareness