CLM - Non-Surgical Management of Myopia II - Week 9 Flashcards

1
Q

What does traditional myopic correction induce and what is the rationale consequence of this?

A

Peripheral hyperopia, leading to myopia progression

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2
Q

Which region of the retina is particularly influential in controlling eye growth? Describe briefly what studies demonstrate this.

A

Studies involving foveal ablation indicate the paracentral retina is influential in controlling eye growth

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3
Q

What is myopic peripheral defocus and how can it be induced?

A

A myopic retinal image shell where the image is in focus at the fovea, but in focus in front of the retina peripherally
Can be induced by increasing the power in the mid-peripheral cornea

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4
Q

Was peripheral hyperopia found be a reliable predictor of myopia progression? What does this suggest about the effect of treating peripheral hyperopia?

A

It doesnt predict development or pregression of myopia. Treating peripheral hyperopia may not be effective.

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5
Q

Describe concentric ring bifocal soft contact lenses, including the distribution of power on its surface, and what kind of image it produces. What other name are they known by?

A

A lens with concentric zones creating 2.00D of simultaneous myopic defocus at distance and near
It is made up of concentric rings of differing powrs which are either correction zones or treatment zones
It produces a clear image on the fovea while simultaneously producing myopic defocus in the parafovea
Also called dual focus lenses

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6
Q

Are dual focus lenses the used in the same way for myopia progression as it is for presbyopia? Explain.

A

No, children do not use them in the same way as presbyopes
Children tend to accommodate for near rather than use the concentric near add (treatment zone) of the contact lens

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7
Q

What was the purpose of the DIMENZ study?How was the control done? Why were patients crossed over between eyes halfway through the study?

A

To determine whether simultaneous presentation of a clear foveal image and peripheral myopic retinal defocus with DF lenses could alter myopia progression in children
It was a paired eye comparison, two groups, one starting with DF lenses on the dominant eye, and the other on the non-dominant eye
Cross-over at the halfway mark to avoid the potential for anisometropia at the end of the trial

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8
Q

What was the finding of the DIMENZ study?

A

It found a reduction in myopia progression and axial length increase with DF lens use

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9
Q

Describe peripheral addition multifocal focal soft contact lenses, including the distribution of power on its surface.

A

It has a central zone for distance vision, circumscribed by a progressive zone for intermediate vision, circumscribed by a peripheral zone for near vision

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10
Q

What do studies in general find about the effect of concentric ring bifocal lenses and peripheral addition lenses on myopia progression and axial elongation?

A

In both lenses, the experimental lenses were favoured over controls (each lens type had 3 and 5 studies respectively in this comparison)

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11
Q

What is vision like with contact lenses designed to slow myopia progression?

A

It is comparable to vision with typical multifocal lens correction. There is good acuity but due to multiple refractive zones, decreased visual performance may be experienced.

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12
Q

How does high illumination + high contrast VA compare in MiSight (DF) lenses vs MF lenses? What about low illumination + low contrast VA?
How do both of these lenses compare in those same conditions vs SVD prescription (list which viewing distance in particular (2))? How do patient reported outcomes compare?

A

MiSight and MF lenses both performed similarly for both high and low light/contrasts levels.
Both lenses performed similar to SVD prescription in high light/contrast conditions, but significantly poorer in low light/contrast conditions for distance and intermediate vision.
They had lower patient reported outcomes.

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13
Q

What magnitude of reduction is typical of special soft contact lenses (in D/y and mm/y)? How does it compare to orthokeratology and atropine?

A

0.20-0.30D/year
0.10mm/year axial length
Slightly less effect than orthokeratology and atropine

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14
Q

What was orthokeratology originally designed for?

A

To eliminate the need for optical correction during the day

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15
Q

What is orthokeratology?

A

Controlled remodelling (flattening) of the central cornea

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16
Q

Consider an orthokeratology lens. List the 4 curves from peripheral to central, and note which is the treatment curve.

A

Paripheral curve
Alignment curve
Reverse curve
Base curve (treatment curve)

17
Q

Describe the results of the LORIC study on the effect of orthokeratology effectiveness on myopia control.

A

Key finding was a 46^% reduction in axial length with orthokeratology lenses over a 24 month period

18
Q

What is the general consensus on the efficacy of orthokeratology lenses on myopia control?

A

Meta analysis generally favours orthokeratology lenses over the control

19
Q

Is orthokeratology highly or poorly accepted by children?

A

Highly accepted

20
Q

How is overall vision in children using orthokeratology?

A

Rated highly

21
Q

How long does it take for vision quality with orthokeratology in childen to become stable?

A

Effects stable at one month

22
Q

What happens to higher order aberrations with orthokeratlogy?

A

Increases

23
Q

What happens to contrast sensitivity with orthokeratology?

A

Reduces

24
Q

What does meta analysis of the literature indicate of the safety of orthokeratology for myopia control? Is it a safe procedure?

A

Favours the control
Though a systematic review found enough evidence to suggest it is a safe option for myopia control

25
Q

A study of orthokeratology in australia found a higher risk of what eye disease? What was found in all cases of this disease?

A

Microbial keratitis
Non-compliance with instructions to lens care in almost all cases

26
Q

Is there any evidence that suggests central corneal epithelial thinning will put patients at more risk than with other modes of contact lens wear?

A

No

27
Q

What are the majority of microbial keratitis (when using orthokeratology lenses) found to be associated with (3)?

A

Inappropriate lens design/material
Tap water for lens cleaning/storage
Lack of overseas industry regulation

28
Q

How should patients be evaluated for orthokeratolgy?

A

On a case by case basis

29
Q

List 6 limitations that studies invesitgating the use of orthokeratology for myopia control generally have.

A

Most are small single site studies without randomisation
Relatively small number of trials
Ethnicity limitations, mostly asian countries
Time period of 2 years
Biological mechanisms not clearly elucidated
Rebound effects

30
Q

Compared to other contact lenses used for myopia control (soft contact lenses), is there a greater risk when using orthokeratology for myopia control?

A

No increased risk

31
Q

Were peripheral aberration control spectacles found to cause any significant reduction in myopia progression? Explain (requirements).

A

No, although children 6-12 were found to have a small but statistically significant reduced rate of myopic reduction with certain lens types.
Only applicable to individuals with parents with myopia.