11. M III - Non-Sx Correction & Management of Myopia I

Question 2

What are the two main focuses of myopia control?

Answer 2

• Slow the progression of existing myopia
• Stop the progression of existing myopia → prevent axial elongation of the globe

Question 3

Myopia control strategies:
Spectacles:
* ...
* ...
* ...
* Monovision
* Periepheral ... control

Contact lenses
* SCLs
* RGPs
* .../ Bifocals
* ...

Other
* ... surgery
* ...
* .../ selective muscarinic antagonists

Answer 3

Myopia control strategies:
Spectacles:
* Under-correction
* Bifocals
* Progressive Addition lenses
* Monovision
* Periepheral aberration control

Contact lenses
* SCLs
* RGPs
* Dual-focus/ Bifocals
* Orthokeratology

Other
* Refractive surgery
* Outdoor activity
* Atropine/ selective muscarinic antagonists

Question 4

Appropriate characteristics of myopia intervention trials:
* Study size → ... per group to detect a ...D change with adequate power
* Randomisation → all factors that influence myopia progression e.g. ..., ..., ..., ... etc.
* Other factors → ..., appropriate control group, ..., test-retest measures, compliance checks

Answer 4

Appropriate characteristics of myopia intervention trials:
* Study size → 50-100 per group to detect a 0.25-0.50D change with adequate power
* Randomisation → all factors that influence myopia progression e.g. age, race, parental refraction, degree of myopia etc.
* Other factors → masking, appropriate control group, cycloplegic refraction, test-retest measures, compliance checks

Question 5

What is the proposed mechanism of of under-correction of the full distance refraction?

Answer 5

Induction of myopic defocus at distance and reduction in accommodative response for near vision.

Question 6

What is the result of under correction as a form myopia control?

Answer 6

Under correction caused even more axial length increase and more myopic progression compared to full correction. Therefore it is more detrimental to under-correct the px. This also produce blur at distance, therefore may impact learning

Question 7

What is the rationale of near addition spetacles for myopia control?

Answer 7

Rationale: reducing accommodative demand at near to reduce myopia progression. Myopic px tend to show reduced accommodative response to near objects, which may be associated with retinal blur and aberrant ocular growth.

Question 8

What are the propsed benefits of a near addition?

Answer 8

• Decreased accommodative demand at near
• Reduces accommodative lag
• Reduces near blur
• Affects phoria → if Eso, will benefit from add

Question 8

The concept of using bifocals for myopia control was introduced in the .... Bifocals provide clear ... and ... vision and has the capacity to control ... for long periods of time. This is a relatively convenient method, compared to using ... or .... However, studies have found no significant difference in ... and ... compared to controls.

Answer 8

The concept of using bifocals for myopia control was introduced in the 1950s. Bifocals provide clear distance and near vision and has the capacity to control accommodation for long periods of time. This is a relatively convenient method, compared to using eye drops or contact lenses. However, studies have found no significant difference in myopia progression and axial length compared to controls.

Question 9

Progressive Addition Lenses have the same advantages of ... as bifocals. It also has other extra benefits:
* Enhanced ... vision
* Absence of ...
* Enhanced ... due to the absence of ...
* Good overall ...
However, studies have found ... over using PALs vs SVDs in ... Children with lower degrees of myopia had ... with use of PALs, meaning that they had ... (...D/yr). It was also found that ... to PALs may be more beneficial. ... (>pd) with significant accommodative ... (>...D) may benefit from PALs.

Answer 9

Progressive Addition Lenses have the same advantages of near addition as bifocals. It also has other extra benefits:
* Enhanced intermediate vision
* Absence of prism jump
* Enhanced cosmesis due to the absence of line
* Good overall acceptanace
However, studies have found no advantages over using PALs vs SVDs in mild to moderate myopic children. Children with lower degrees of myopia had slightly difference with use of PALs, meaning that they had less myopic progression (0.16D/yr). It was also found that earlier exposure to PALs may be more beneficial. Near esophores (>2pd) with significant accommodative lag (>0.43D) may benefit from PALs.

Question 10

What is the logic behind using Monovision for myopia control?

Answer 10

Monovision reduces accommodative effort during near work, which may potentially slow myopic progression. (However, may compromise binocular vision)

Question 11

What were the results from studies using monovision for myopia control?

Answer 11

Myopic progression in the near corrected eye was significantly less than in the distance corrected eye (0.36D/yr difference). This indicates that myopic retinal defocus was an anti-myopiagenic stimulus
* however this is different from bilateral undercorrection, which resulted in more progression.

Question 12

• SVD soft contact lenses ... myopic progression compared with SVD spectacles.
• SVD rigid contact lenses ... myopic progression and ... axial length compared with SVD spectacles.
• RGPs and SCLs had slight difference in ... over a 3 year study, however, there were no significant difference in ... between groups.

Answer 12

• SVD soft contact lenses do not significantly alter myopic progression compared with SVD spectacles.
• SVD rigid contact lenses do not significantly alter myopic progression and do not significantlly alter axial length compared with SVD spectacles.
• RGPs and SCLs had slight difference in cycloplegic refraction over a 3 year study, however, there were no significant difference in axial length between groups.