Week 7 - Myopia management Flashcards
Peripheral hyperopic defocus mechanism
• The image falls behind the retina in myopia, known as peripheral hyperopic defocus
• The eye uses this as a stimulus to grow to bring these images on to the retina
• The plus power in myopia management contact lenses reduces peripheral hyperopic defocus
MiSight lenses:
• CE marked for myopia management
• Coopervision
• BVP: up to -10.00DS
Treatment zones of myopic defocus=+2.00DS (not adjustable)
MiSight advantages vs disadvantages
Advantages:
• Superhero powers?
• No contact lens cleaning required
• Convenient
• Safer for sports e.g. football (risk of soil contamination)
Disadvantages
• Risk of contact lens related dry eye
• Risk of hypoxia
• More expensive
• Not appropriate for astigmatism > 1.00 DC
Biofinity multifocal lens:
Centre distance (CD) lens
• Distance prescription zone
• Progressive/intermediate zone
• Near Add zone
• Lens edge
Biofinity multifocal lens: Advantages vs disadvantages
Advantages:
(in comparison to MiSight)
• Less risk of contact lens related dry eye
• Lower risk of hypoxia
• More economical
Disadvantages:
• Requires cleaning
• Not CE marked for myopia control, “off license”
• Greater risk of infection than dailies? (1.56x greater risk with than reusable but risk of vision loss from infection greater wit reusable)
• Not as convenient
Proclear MF:
• Coopervision
- Can come in Spherical or Toric
Proclear MF: Centre distance (CD) lens
• Distance prescription zone
• Progressive/intermediate zone
• Near Add zone
• Lens edge
Proclear MF: Advantages and Disadvantages
Advantages:
• Wide BVP range: Suitable for high myopes
• Corrects astigmatism
• Less expensive than MiSight daily lens
Disadvantages
• Greater risk of contact lens related dry eye than Biofinity MF
• Greater risk of chronic hypoxia
• Requires cleaning
• Greater risk of infection than dailies?
• Not as convenient
Other contact lenses
• Mylo Contact lens
- A range of prescriptions resulting in multiple focal points at different distances from the retina
- Mylo lens design: extended depth of focus
• Natural view ME
- Visioneering technologies incorporated
- CE marked for myopia management
- Daily disposable
Contact lenses for myopia management
Orthokeratology
• Lenses worn overnight=no spx or cls during the day
• Suitable for children with myopia up to -4DS and no more than 1 DC
Contact lenses for myopia managemen
Orthokeratology: Advantages and Disadvantages
Advantages
•Don’t need to wear spx or cls during the day: Beneficial in sport, swimming . No risk of contact lens drying out during the day
• 18R can be completed by the parent
Disadvantages
• Adaptation period up to 2 weeks whilst vision stabilises
• Greater lens awareness during fitting and during initial 2 weeks of
wear
• Requires more appointments for fitting/aftercare
• More rigorous cleaning required (lenses changed every 6 months)
• More difficult to handle
• Greater risk of lens adhesion, corneal abrasion and infection
Comparisons between orthoK and soft lenses
> No difference in adverse events between soft contact lenses and ortho-k
Greater risk of pseudomondas infection and acanthomoeba infectior in ortho-K wear
Risk of Sil hyd extended wear infectious keratitis is 0.25% versus daily sil hyd soft cl wear: 0.12%
Fitting: H&S
• Aim of the H&S:
Determine any contraindications and start to consider the best cont: lens choice from: hobbies, GH, allergies, medications
General observation:
Does the child speak directly to you or through the parent?
Are they nervous or anxious?
Are they excited and confident?
Initial contact lens selection:
• Discussion with parent and child
• Ocular surface health
• Spectacle prescription
Over-Refraction and VA assessment
- Fit trial frame on patient
- Place occluder in front of left eye
- Check VA of the right eye and record
- Swap the occluder for a +2.00DS lens in front of the left eye
- Choose a letter from the smallest line seen
- Offer +0.25DS to the right eye: ‘better, worse or the same
- If it is ‘better’ or ‘the same’= give the plus
- Offer +0.25DS again to the right eye until px says vision with the lens is ‘worse’
- If it is ‘worse’ do not give the plus
- Recheck VA of right eye
- If VA has worsened, offer -0.25DS to the right eye ‘clearer or smaller and darker’
- If it is ‘clearer’ AND improves VA, the -0.25DS is given
ONLY give -0.25DS if it improves VA - Repeat for left eye
- Remember to check near visual acuity as well (monocularly)
NB: over refraction and visual acuity
NB
• Visual acuity can range from 0.2LogMar (6/9.5) to 0.00LogMAR (6/6) or even better
• Depends on type of contact lens, adaptation period, any uncorrected astigmatism
• Depends on near Add: +2.00DS or +2.50DS (with Biofinity or Proclear)
• Older children may initially notice ghosting, reduced contrast, glare/haloes around lights. Worse in low light levels
Teaching insertion and removal
• MUST be done by the child
• Ortho-K lens is the exception
Advice:
• WT: minimum 6 hours, up to 12 hours depending on ocular health, contact lens material
• Gradually increase WT (increase by 2hrs/day)
• Advice on the usual dos and don’ts
