A Review of Control and Treatment for Myopia
Myopia is well known for human over 2000 years. Myopia is the single most popular eye disease in the world. It is an eye defect with uncorrected refractive error which affects parallel light focus the image in front of the retina when accommodation is relaxed. It usually can be obtained when the eye has grown too long. Myopia also called short-sightedness is reaching epidemic proportions, especially in Asia, due to urbanization and increased screen and text-based activity. The number of myopias in the world is estimated to grow from 1.6 billion now to a staggering 2.5 billion by 2020. Uncorrected myopia affects learning and development, and high myopia creates a significant risk of retinal malfunction leading to vision loss. Myopia can lead to a lot of adverse effects on different aspects, such as self-esteem, career choice, and ocular health. Therefore these negative effects will contribute to an adverse social development and a strike on government economy directly. The methods of myopia control are those designed to control refractive development by functional means such as reducing the demands upon either accommodation of convergence, or by controlling intraocular pressure. Other methods of myopia control including the wearing of conventionally fitted rigid contact lenses and orthokeratology. Although contact lenses also alter the stimuli to accommodation and convergence when compared with spectacles, due to their closer vertex distance and the absence of induced prismatic effects, these differences are relatively small and are not usually considered to be important in myopia control. Functional methods of myopia control which will be considered here are vision therapy, biofeedback training, distance undercorrection, distance overcorrection, bifocals and various pharmaceutical agents. There are many different treatment methods especially surgical correction for myopic patients to improve their vision. During the past half century a large number of surgical procedures have been devised for the purpose of reducing myopia. Some of the earlier procedures had names such as scleral reinforcement, scleral resection, keratomileusis, lamellar keratoplasty, epikeratoplasty and keratophakia. However, most of them were outdated. Most of the refractive surgery procedures in use today have been designed to reduce myopia by flattening the cornea, thus increasing the focal length of the eye’s optical system to make it a better fit for the elongated eye. These procedures include radial keratotomy (RK), laser photorefractive keratectomy (PRK), automated lamellar keratoplasty (ALK), laser in situ keratomileusis (LASIK), and intrastromal corneal ring (ICR). This paper reviews the efficiency for different myopic control procedures and compares all different treatment methods for myopia especially to compare all the advantages and disadvantages. It also discusses different surgeon for myopic treatment to find out which surgical treatment is the best for myopic patient. Therefore it includes the discussion of the control procedures and surgical treatments for myopia, analysis of the advantages and disadvantages for them and their limitation. Control procedures for myopia
Vision therapy attempts to reduce the pre-existing amount of myopia by training the patient to improve the accuracy of his or her accommodative response. Unfortunately, in most published reports where these techniques have been studied, the quantified test variable was not refractive error but unaided visual acuity. Lin and Ko (1988) described an 18-month study of 604 Taiwanese primary school children in the same grade (ages not reported), who were randomly assigned to two groups. The experimental group, consisting of 390 children, practised 'far gazing and eyeball exercises' three times a day, while the control group of 214 children did not perform any therapy. In this investigation, mean changes in...
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