CLM - Non-Surgical Management of Myopia II - Week 9 Flashcards
What does traditional myopic correction induce and what is the rationale consequence of this?
Peripheral hyperopia, leading to myopia progression
Which region of the retina is particularly influential in controlling eye growth? Describe briefly what studies demonstrate this.
Studies involving foveal ablation indicate the paracentral retina is influential in controlling eye growth
What is myopic peripheral defocus and how can it be induced?
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
Was peripheral hyperopia found be a reliable predictor of myopia progression? What does this suggest about the effect of treating peripheral hyperopia?
It doesnt predict development or pregression of myopia. Treating peripheral hyperopia may not be effective.
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 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
Are dual focus lenses the used in the same way for myopia progression as it is for presbyopia? Explain.
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
What was the purpose of the DIMENZ study?How was the control done? Why were patients crossed over between eyes halfway through the study?
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
What was the finding of the DIMENZ study?
It found a reduction in myopia progression and axial length increase with DF lens use
Describe peripheral addition multifocal focal soft contact lenses, including the distribution of power on its surface.
It has a central zone for distance vision, circumscribed by a progressive zone for intermediate vision, circumscribed by a peripheral zone for near vision
What do studies in general find about the effect of concentric ring bifocal lenses and peripheral addition lenses on myopia progression and axial elongation?
In both lenses, the experimental lenses were favoured over controls (each lens type had 3 and 5 studies respectively in this comparison)
What is vision like with contact lenses designed to slow myopia progression?
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.
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?
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.
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?
0.20-0.30D/year
0.10mm/year axial length
Slightly less effect than orthokeratology and atropine
What was orthokeratology originally designed for?
To eliminate the need for optical correction during the day
What is orthokeratology?
Controlled remodelling (flattening) of the central cornea
