5.1.1.Chooses, fits and orders soft lenses.

Question 1

1. History

Answer 1

• In date ST
• Contraindications?
• GH - Diabetes? Meds? Atopy may indicate dry eye or potential solution toxicity?
• What are px’s expectations?
• Pxs lifestyle?
• Desired wearing schedule?
• Previous lens wear?
  *

Question 2

2. Preliminary exam

Answer 2

• HVID & VVID – TD of CL 2mm greater than HVID
• K’s – BOZR should be 0.6-1.0mm flatter than the average K reading
• Only real option for very flat cornea is J&J as 9.0 BC available
• Nafl, tear assessment, evert lids
• Rx – correct for change in vertex distance if spec rx > + or – 4.00
• Toric lens – must adjust in both meridians
  *

Question 3

3. Lens selection

Answer 3

• Consider max WT
• Limitations of Rx
• Px’s wants and needs
• Dry eye?
• Opteyes / Bioinfinity: Dk/t 160, WC 48%, modulus 0.75 – 1st choice
• Umere / clarity 1 day: Dk/t 86, WC 56%, modulus 0.5m – 1st choice
• Vitrea / daily ACP: Dk/t 26, WC 69%

Question 4

Hydrogel vs SiHy

Answer 4

• SiHys are higher modulus/stiffer – px may be more aware of lens on eye – cause more mechanical issues
• Longer WT = SiHy as higher Dk/t & less water so they dry out less
• Shorter WT & dryness = hydrogel is good for comfort as softer, higher wettability so more comfort in the short term
• Higher Dk/t = less risk of hypoxia and resultant complications incl. neovasc/infiltrates
  *

Question 5

4. Assessment of fit (direct observation)

Answer 5

• Wash hands
• Place sclera onto lid for insertion & slide onto sclera for removal
• Lens details & settling time
  Fit assessment
• Centration – well-centred, 1mm at each side of cornea
• Coverage – full no limbal crossing
• Lag/sag – 0.2-0.5mm, ~0.25mm
• Movement on blink ~0.8mm
• Push up test – push up smooth, good recovery, ~50% tightness
• Score comfort & vision out of 10
• VA & OR
• Adjustment of lens for best fit
• Flat fit = steepen by increasing TD or reducing BOZR
• Steep fit = flatten by decreasing TD or increasing BOZR
• Writing order - manufacturer / CL name / BC / TD / rx

Question 6

Monthlies, all steps with MPS

Answer 6

 Rub – 15s each side
 Rinse
 Fill case to ridge inside
 Ready to store over night
 In the morning – insert lenses, empty case of all solution, rinse with MPS and leave to airdry facedown over the day with the caps off to avoid condensation
 30 days not 30 wears
 Replace lens, lens case & solution after 30 day

Question 7

Easypurpose – best (CooperVision HyCare)

Answer 7

• Polyhexanide (PHMB) – disinfectant / preservative
• Sodium hyaluronate – helps stabilise tear film, reduce friction between lens and ocular surface
• Sodium chloride – tonicity, maintains ideal CL salt solution of 0.9% (too low – cornea swells, too high, cornea drys)
• Sodium phosphates – buffer to ensure neutral pH to match tear film
• Poloxamer – surfactant used to clean lenses
• EDTA – chelating agent, prevents lens deposits (i.e. calcium) / enhances action of preservatives

Question 8

Ultrapurpose (biotrue, b&l

Answer 8

more enhanced protein management system, and has a dual disinfecting system

Question 9

Peroxide solution

Answer 9

(Coopervision – Refine One Step)
- 3% hydrogen peroxide
- Sodium chloride – tonicity
- Sodium phosphates – buffer
- Poloxamer – disinfecting/cleaning
- HEDP
 Catalyst to neutralise peroxide – platinum disc/tablet
 Lenses into baskets, rinse each lens in the holder for 5 seconds with peroxide solution, fill the lens case up with solution to the marked line, place lens holder inside of case and close cap, solution will bubble – ensure lenses upright and fully immersed. Allow lenses to soak for at least 6 hours

Question 10

Toxicity/preservative allergy resolution

Answer 10

 More gentle solutions
 Hydrogen peroxide care system
 Switch to daily lenses

Question 11

DOs +DONTs

Answer 11

 Good general hygiene, washing hands etc
 Good lens and case hygiene
 Insert lenses before applying makeup

 Sleep in lenses
 Swim/shower/water near lenses
 Do not wear lenses if any pain/redness/discomfort
 Change cleaning regime without first consulting optometrist
 Wear for longer than advised

Question 12

3rd Gen SiH:

Answer 12

• Aquaform technology - The advanced silicone channels in the material transport oxygen so efficiently that less raw silicon is required. This sustains inherent wettability and facilitates optimal water content.
  
  • Also means less cross linking so lower modulus. No surface treatment or internal wetting agent – novel polymer
  • Long chain silicone core with hydrophilic groups attached, therefore no surface treatment or wetting agents needed to render surface hydrophilic

Question 13

Makes adjustment to lens for best fit

Answer 13

• Steep fit (flatter needed) - Decrease diameter (lower sag) or increase BC
• Flat fit (steeper needed) - Increase diameter (higher sag) or decrease BC
• Generally just change manufacturer

Question 14

Contraindications:

Answer 14

• Presence of an active eye disease, inflammation or injury such as corneal abrasion.
• Use of medications (including eye drops) that are contraindicated with contact lenses or care solutions e.g. beta blockers
• Allergy to contact lens materials or care solutions.
• Inability to adhere to lens care instructions either due to age, illness, disability or other conditions.
• Inability to insert and remove contact lenses without help.
• History of non-compliance with wearing and replacement schedules as well as lens care instructions.
• Moderate-Severe dryness - chronic blepharitis
• Health conditions such as diabetes (refractive error unstable). Diabetes also increases MK risk
• Pterygium obstructing lens from fitting