The sims 3 cc male circle lenses
While orthokeratology is an effective tool in delaying axial elongation 19, 29, children have to sleep with lenses at least 8-10 hours for necessary corneal curvature and orthokeratology is only applicable to the children with low and moderate myopia.
These findings encourage the use of the optical devices for myopia control. A study showed lenses with myopic defocus in the peripheral retina delay axial length elongation 28, while lenses imposing peripheral hyperopic defocus have the opposite effect, increasing the rate of elongation 24, 27. Another alternative are certain specially designed contact lenses including orthokeratology and multifocal soft contact lenses (MFSCLs) which have been shown to delay induced myopia progression by generally incorporating 'positive power' to reduce the hyperopic defocus and/or impose myopic defocus in peripheral retina 24 - 27. Atropine eyedrops which seem to be an effective way to slow the progression of myopia are also limited by drug side effects such as photophobia, abnormal accommodation and myopic rebound. However a Cochrane Database Systematic Review in 2011 concluded that bifocals, progressive addition lenses and contact lenses yield disappointing long term results for myopia control 15 and specially designed spectacle lenses have minimal effect 23. Unfortunately, this disease has no definitive cure by traditional optical interventions.Īt present, many options for slowing progression of myopia have been proposed and evaluated, such as progressive addition of executive bifocal spectacle lenses 12 - 14, peripheral defocusing lenses 15, contact lenses 16, outdoor activities 17, pharmacological agents such as atropine eyedrops 18,overnight orthokeratology 19 - 21, and multifocal soft contact lenses 22. It was estimated that 1.5 billion people were affected in 2010, but this number is expected to rise to 5 billion by 2050 4. Data from China, Taiwan and Japan indicate that severe axial myopia has become one of the main causes of untreatable vision loss throughout the world, often due to its irreversible complications, such as retinal detachment, macular degeneration, macular hemorrhage, choroidal neovascularization and open angle glaucoma 10, 11. This axial lengthening process begins in childhood and progresses remarkably during the adolescent growth period 9. The most common form of myopia worldwide is secondary to elongation of the axial length of the eye, termed axial myopia. The incidence of myopia is ~ 95% in the youngster population from China/ Korea 1, 2 and can occur when children are as young as 5-6 years old 6 - 8.
However, recent increased prevalence in the world, especially in Asia, has forced the scientific society to view it differently 1 - 5. Myopia is traditionally considered as mere refractive error. In this manuscript, we aim to review the basics of myopia, recent advances in contact lenses to control myopia with emphasis on MFSCLs, define the elements for proper MFSCL fittings (such as pupil size, aberrations, accommodation and centering), discuss the potential rebound effect after discontinuation of contact lenses, and future directions for improvements of contact lenses for the control of myopia. Compared with the other traditional methods of controlling myopia, MFSCLs allow myopic patients to better maintain their clear visual quality and slow myopia progression.
Use of MFSCLs has especially increased in recent years due to the growing demand to slow myopia progression during patient's adolescent growth period to avoid pathological myopia in adulthood. At present, many options for slowing progression of myopia have already been proposed and evaluated such as progressive addition of executive bifocal spectacle lenses, peripheral defocusing lenses, overnight orthokeratology, pharmacological agents such as atropine eye drops, and multifocal soft contact lenses (MFSCLs). Elevating levels of myopia increase the risk of vision impairment, and therefore, high myopia has become one of the main causes of untreatable vision loss throughout the world due to its irreversible complications. Myopia is an important public health problem due to its prevalence and significant public health cost.