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  1. 1. What is the mechanism of multifocal lenses that may slow progressing myopia?

    The mechanism for multifocal contact lenses in myopia control is the same for orthokeratology – “peripheral retinal defocus theory”. The hypothesis of this theory is that paracentral hyperopic defocus encourages the axial length increase so those areas are in focus (the eye grows so the retina is at the focal point). Increased axial length results in myopia progressing and central blur, we correct the vision and the process happens again. Soft multifocal contact lenses provide a relative hyperopic prescription in the peripheral aspect of the lens, focusing paracentral beams on the oblate shaped retina.

    2. What are the numbers of myopia and myopic ansimetropia that may cause amblyopia?

    Bilateral myopia greater than -8.00DS and anisometropic myopia greater than -3.ooDS.

    3. The effect OK contact lens is flattening of cornea to treat myopia and slow progressing it?

    The mechanism for orthokeratology myopia control is the same as multifocal contact lenses – “peripheral retinal defocus theory”. The hypothesis of this theory is that paracentral hyperopic defocus encourages the axial length increase (the eye grows so the retina is at the focal point). Increased axial length results in myopia progressing and central blur, we correct the vision and the process happens again. Orthokeratology lenses achieve this by creating a steepened peripheral cornea, focusing paracentral beams on the oblate shaped retina.

    4. When you treat myopic children, what do you do to slow progressing of myopia? You use atropine or OK contact lens?

    Atropine in very young children – it is easily administered by parents on weekends (if the child won’t have drops I tell parents to instill a drop whilst they are asleep – kids sleep through just about anything!) Once the child is old enough to handle the lenses and take responsibility for them I move them to Orthokeratology lenses for two reasons, it gives them clear vision without glasses and it is more of a long-term solution as myopia is expected to progress until 17 years of age and there a not strong studies on the long-term (beyond a few years) effects of bilateral weekend atropine use.

    5. You use bifocal glasses if the patient has esotropia at near? You advise the patient to remove glasses at near and don’t wear bifocal glasses? What is your opinion?

    If the patient has an esotropia at near then we have a bigger problem than myopia and I would pursue treatment of the esotropia rather than the myopia. The myopia is the least of my problems if they have strabismus. If the child has a esophoria I would prescribe BF or progressive lenses (I prefer progressive lenses as they are more attractive for older kids) and that way they do not have to bother taking their glasses on and off. Additionally, the level of their myopia may be more than what I want to prescribe at near.

    6. Myopia usually doesn’t cause asthenopia, when does myopia cause it?

    Sometimes when you make a large change to a patient’s glasses prescription, especially if there is a large change between eyes.

    7. What dose peripheral defocus mean?

    Paracentral hyperopic defocus occurs in a myopic eye when corrected with negative lenses because of the oblate shape of a myopic eye.

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