Myopia Control
Contact Lens
The peripheral retina may contribute to emmetropization. On the other hand, unrestricted central vision is not sufficient to ensure normal refractive development, and the fovea is not essential for emmetropizing responses. (Smith et al, 2005)
Peripheral Vision Can Influence Eye Growth and Refractive Development in Infant Monkeys
Eye care practitioners correct Myopia with contact lenses and Spectacles which are known to correct only central refractive errors. The periphery remains uncorrected, resulting in a peripheral hyperopic defocus. (Koffler H, Sears J, 2013)
Myopic eyes are known to be more hyperopic in the periphery than at the fovea, while hyperopic eyes are known to be more myopic in the periphery than at the central fovea. (Millodot, 1981; Mutti et al, 2007).
This peripheral hyperopic defocus was found to stimulate axial length growth, until the peripheral images reaches the peripheral retina. Researchers have thus hypothesized that peripheral myopic defocus reduces axial length growth, which brings about the ability to control Myopia. (Kang and Swarbrick, 2011).
Both the Ortho-keratology Lenses and Distance-centre Soft Bifocal lenses have been found effective in slowing down the progression of Myopia.
i) Orthokeratology:
Orthokeratology is a design of a rigid gas permeable lens, worn overnight to reshape the cornea curvature temporarily for the correction of Myopia and Astigmatism. These cornea refractive therapy would be indicated to people with low to mild myopia, (-4 diopters or less).
The flatter central zone which is closer to the cornea exerts gentle pressure while the periphery surrounding the central visual zone is steeper than the cornea, allowing room for the cornea to mould and change its shape. With a steeper peripheral curvature, light rays would be focused in front of the retina. This change in curvature enables peripheral myopic defocus which is believed to
The peripheral retina may contribute to emmetropization. On the other hand, unrestricted central vision is not sufficient to ensure normal refractive development, and the fovea is not essential for emmetropizing responses. (Smith et al, 2005)
Peripheral Vision Can Influence Eye Growth and Refractive Development in Infant Monkeys
Eye care practitioners correct Myopia with contact lenses and Spectacles which are known to correct only central refractive errors. The periphery remains uncorrected, resulting in a peripheral hyperopic defocus. (Koffler H, Sears J, 2013)
Myopic eyes are known to be more hyperopic in the periphery than at the fovea, while hyperopic eyes are known to be more myopic in the periphery than at the central fovea. (Millodot, 1981; Mutti et al, 2007).
This peripheral hyperopic defocus was found to stimulate axial length growth, until the peripheral images reaches the peripheral retina. Researchers have thus hypothesized that peripheral myopic defocus reduces axial length growth, which brings about the ability to control Myopia. (Kang and Swarbrick, 2011).
Both the Ortho-keratology Lenses and Distance-centre Soft Bifocal lenses have been found effective in slowing down the progression of Myopia.
i) Orthokeratology:
Orthokeratology is a design of a rigid gas permeable lens, worn overnight to reshape the cornea curvature temporarily for the correction of Myopia and Astigmatism. These cornea refractive therapy would be indicated to people with low to mild myopia, (-4 diopters or less).
The flatter central zone which is closer to the cornea exerts gentle pressure while the periphery surrounding the central visual zone is steeper than the cornea, allowing room for the cornea to mould and change its shape. With a steeper peripheral curvature, light rays would be focused in front of the retina. This change in curvature enables peripheral myopic defocus which is believed to
References: Rose KA, Morgan IG, Smith W, Burlutsky G, Mitchell P, Saw SM. (2008) Myopia, lifestyle, and schooling in students of Chinese ethnicity in Singapore and Sydney. Arch Ophthalmol. 2008 Apr;126(4):527-30 Millodot M Walline JJ, Long S, Zadnik K. (2004) Daily Disposable Contact Lens Wear in Myopic Children. Optom Vis Sci. 2004 Apr;81(4):255-9 Cho P, Cheung SW, Edwards M Bruce H. Koffler, James J. Sears, Myopia Control in Children through Refractive Therapy Gas Permeable Contact Lenses, American Journal of Ophthalmology Volume 156, Issue 6, 2013, Pages 1076–1081.e1 Kang P, Swarbrick H Stapleton F, Keay L, Edwards K, et al. The incidence of contact lens-related microbial keratitis in Australia. Ophthalmology. 2008;115:1655-1662.