Problem Solving Soft CL Fits

Question 1

Describe discomfort and the reasons for it in soft CLs?

Answer 1

2 main aspects of fitting design that can cause discomfort:
1. Total diameter
2. Inappropriate fit – too steep/flat
Don’t forget non-fitting related possibilities:
- Foreign body – something on or under lens
- Lens inside out – takes appearance of loose lens, moves around too much
- Lens damage – look at the lens before placing in eye
- Lens spoilation – extra material gathered on lens

Question 2

Describe total diameter (too large or too small) and what to do in soft CLs?

Answer 2

Total Diameter:
* Too Large:
o Can lead to ↑ pressure & therefore conjunctival indentation – gives appearance that lens isn’t moving enough
o If there is poor flexure (way lens is bending, to do with modulus, how stiff lens is) it can lead to superior arcuate staining
o Limited options in standard lenses, consider specialist lens
o Learn which standard lenses look smaller once they have settled on eye:
 Efron advises Air Optix Night & Day and Soflens
* Too Small:
o Can lead to peripheral corneal staining – don’t have full corneal coverage & getting parts of corneal are drying out
o Limited options in standard lenses, consider specialist lens
o Learn which standard lenses look larger once have settled on eye:
 Efron advises Proclear, Air Optix qua and Acuvue Oasys 1-day

Question 3

Describe inappropriate fitting (too loose and too tight) in soft CLs?

Answer 3

• Too loose:
  o Steepen base curve (e.g. started 8.8, then try 8.4) – DECREASE BOZR
  o 1st thing to check is whether lens is inside out
  o Changing to same lens but in steeper Base Curve doesn’t always help as lenses are so thing that it may not tighten much
  o Consider changing to lenses that are known to have tighter fit
  o Increase Total Diameter (may not have this option in standard lenses)
• Too tight:
  o Discomfort tends to be towards end of day
  o Flatten base curve (e.g. started 8.4, then try 8.8) – INCREASE BOZR
  o Decrease Total Diameter (may not have this option in standard lenses)

Question 4

Describe poor VA in soft CLs?

Answer 4

• Possible causes:
  o Uncorrected astigmatism (should find this on over-refraction)
  o Lens deposits – lens reached end of its life or not been cleaned properly – could be lipids, proteins
  o Poor surface wetting – not getting nice layer of tears on blink
  o Lens imperfections – lens could be split or damaged
• Examine lens with slit lamp & complete over-refraction
  o If there is no obvious cause then try replacing lens (& ensure lens is the correct Rx & not inside out)

Question 5

Describe variable vision in CLs?

Answer 5

• Possible causes:
  o Excessive lens movement – flat fit or inside out
  o Incorrect BVP – px may be over-misused (especially towards end of day)
  o Poor binocular balance – especially in young pxs
  o Poor tear film – not got a good aqueous layer or a good lipid layer, px has dry eye  shorter TBUT leads to variable vision -> make sure to assess TBUT
• Have good look at lens on eye
• Check over-refraction – may need to go back to actual refraction