Soft CLs

Question 1

Why may you recommend extended wear CLs?

Answer 1

Wake-up n go roles such as on-call emergency services, mothers waking up for newborns, long-working hours

Question 2

Describe corneal infiltrate events (CIEs) and their prevalence in DD vs reusable wearers

Answer 2

Corneal inflammation due to CL wear - white spot (WBC collection moving into cornea from limbal blood vessels e.g. sight-threatening microbial keratitis)
X12 lower in DD users

Question 3

Generally what’s the minimum Dk (O2 permeability) of DD CLs to avoid corneal oedema/swelling?

Answer 3

24%

Question 4

State 3 techniques for measuring friction coefficients in CLs

Answer 4

finger rub, inclined plate, microtribometer

Question 5

Describe 3 methods of soft CL manufacture

Answer 5

Lathing - wide power/parameter range for custom CLs but expensive
Cast moulding - cheap, mass production (no custom lenses)
Spin-casting - efficient but no opportunity for custom parameters

Question 6

Explain the draping effect in soft CLs

Answer 6

Average cornea ~ 8.1mm, at eye temp. the lens shrinks/steepens by 0.3mm so lens (8.3mm) sag closer matches cornea

Question 7

Explain how edge profiles relate to conjunctival staining

Answer 7

Knife edge: moves least, more staining/comfortable
Round edge: moves most, less staining/comfortable

Question 8

Explain how you would perform over-refraction following CL fit

Answer 8

Add DS to trial frame bringing refractive state close to BS (sphCL) or ocular refraction K (torics)
Check monoVAs and fog with +1.00 then HIC Binocular balance, check VAs and do Binocular add if needed

Question 9

Other than specs/CLs what other options are there for presbyopes?

Answer 9

Moving IOLs
Pinhole corneal inlays
Experimental scleral surgery
MF laser surgery
Pharmaceutical treatment