Week 7 - Soft CL fitting 2

Question 1

What are 2 coloured daily lenses, and their manufacturer?

Answer 1

• FreshLook Iluminate by Alcon
• FreshLook One-Day by Alcon

Question 2

What are 4 types of coloured monthly lenses and their manufacturers?

Answer 2

• Alcon: FreshLook Colorblends / Colors/ Dimensions
• Alcon: Air Optix Colors
• Coopervision: Expressions colors
• Bausch & Lomb : SofLens Natural colours

All can come in a variety of prescriptions

Question 3

What company makes Annual coloured lenses?

Answer 3

• Cantor cosmetic
- All lenses available in wide spherical or toric prescriptions

Question 4

What should be done if we see a joke shop selling theatrical lenses?

Answer 4

• Issue them an AOP/GOC leaflet
• Report them to local council
• Phone GOC

It is illegal to sell without fitting and ongoing care.

Question 5

Which theatrical lenses are available?

Answer 5

• Clear colors phantom lenses - but has Dk of 10
• Cantor and nissel - wide range of Rxs available

Question 6

What are some examples of specialist companies?

Answer 6

• Mark Ennovy
- Daily to 3 monthly, tinted lenses with up to 30Dioptres Rx, up to 8Dioptres astigmatism. Can also provide myopia management lenses.
• David Thomas (bought by Menicon)
- Daily to longer term replacement lenses
- provides soft lenses for keratoconus, with ranges of +45.00Ds to -30.00Ds sphere, and up to 10.00 Ds of Cyl

Question 7

What specialist company provides for theatrical lenses?

Answer 7

• Cantor and Nissel
- Wide range of soft + rigid lenses, up to +30.00 Ds sphere and up to 6Ds astigmatism
- Lenses for keratoconus
- Wide range of prosthetic and theatrical lenses
e.g a phakic patient

Question 8

What 6 topics are assessed for a fit of a contact lens?

Answer 8

• Centration and coverage
• Lens movement in blink
• Lag (and sag?)
• Push up test
• Tightness
• Comfort

Question 9

How is centration and coverage assessed?

Answer 9

Diffuse beam on slit lamp
• Is the lens centred in the primary position?
• Is the cornea completed covered?
• Does the cornea remain covered in all positions of gaze? There should be overlap onto the conjunctiva of about 1-1.5mm all around the lens.

Question 10

How is Lens movement on blink determined?

Answer 10

• Use (16-25x) mag
  • Easier to assess when the Px is looking up
  • Ask them to blink naturally
  • Lens movement should be observed (can use a 1mm beam or 0.3mm beam
  • A normal movement is 0.2-0.4/0.5mm

Question 11

How is Lag and Sag determined?

Answer 11

• Measure if horizontal and vertical movement on lens excursion
- With Px in primary vision gaze, use slit lamp to adjust to match width of overlap of contact lens onto sclera
- When Px looks to nasal/temporal, slit lamp relocated to new overlap, measuring for comparison
- I.e Overlap is 0.5mm primary gaze, and 1mm nasally, therefore theres 50% increase

Question 12

What is the push up test?

Answer 12

• AKA the digital displacement test
• To assess the tightness of the lens
• Using the lower lid to nudge the lens off centre and monitor how easy it was to move and how quickly it returns to the centre
• Accuracy of the push-up test comes with practice
• Research shows this test has good predictive value for a successful fit

Question 13

How is the push up test recorded?

Answer 13

• Recorded as description or percentage

100% = lens impossible to move
0% = lens falls away from the cornea without lid support
50% = perfect

Question 14

How is tightness recorded?

Answer 14

Summary of the fit
100% - tight
50% - ideal
0% - loose

Question 15

How is comfort measured?

Answer 15

• A Yes/Ni scale can be used
• Or a score out of 10 with 10 being perfect (9 or above is desirable).

Question 16

What are other methods of fit assessment?

Answer 16

• Retinoscopy - checking the optic zone covers the pupil
• Keratometry - distortion will be seen if the lens is not aligned. Improved post blink when tight and between blinks when loose

Question 17

What should an Ideal CL fit include? ( 6 points total)

Answer 17

• Good comfort
• Clear vision
• Centred
• Aligned to conjunctiva
• 0.2mm to 1mm of movement (depends on the source)
• Smooth recovery from Push-up test

Question 18

What are indications if a steep/tight fitting CL?

Answer 18

• No/minimal lens movement
• Limbal vessels constricted
• Conjunctival indentation
• Conjunctival redness
• Vision improves immediately post blink
So resolve: select flatter BOZR

Question 19

What are the indications of a flat/loose fit?

Answer 19

• Excessive lens movement >1mm of lag
• Poor centration, usually drops inferior
• Buckling at lens edge
• Lens awareness
• Variable vision - worst immediately post blink
To resolve, select a steeper BOZR

Question 20

What are the minimal requirements for an acceptable-fitting soft lens?

Answer 20

• Full corneal coverage at all times
• Some movement on blink and/or version
• Absence of excessive movement
• No conjunctival indentation or edge stand off

Question 21

What is an Over-refraction check?

Answer 21

• Same as normal subjective refraction
• For spherical lens, carry out BVS (+ first as normal) and check if VA is adequate
• If VA reduced, conduct cyl assessment as the px may need toric lens
• If VA fluctuates, think about fit of lens