Myopia is a refractive error in which parallel rays of light are brought into focus in front of the retina when accommodation is not used (Grosvenor and Goss, 1999; Saw, et al., 1996). This causes distant objects to appear blurry while nearby objects can still be seen clearly. Myopia can be classified in various ways: cause (axial or refractive) (Emsley, 1953), age of onset (congenital, juvenile onset, early adult onset, or late adult onset) or degree (low, intermediate or high) (Grosvener, 1987). When classifying myopia by degree, high myopia is indicated when myopia is greater than 6.00 diopters, intermediate between 3 and 6 D, and low 0.50 to 3.00 D (Fitzgerald, Chung, & Krumholtz, 2005) . Axial myopia is due to axial elongation of the vitreous chamber diopters, meaning the eye becomes too long for its refractive power. (Benjamin, 1998) Refractive myopia is caused by an error in the dioptric power of the eye due to the change in the refractive index of the lens (index myopia), the increase in the curvature of the refractive surface of the cornea (curvature myopia) or to an anomaly of the depth of the anterior chamber (anterior chamber myopia) (Borish, 1970). Further research (Strang, Winn, & Bradley, 1998) has shown that most cases of significant myopia are primarily due to axial myopia. Theories about the cause of myopia are currently incomplete. It is thought that there is some genetic aspect but it can also be induced by an excessive amount of close work which stimulates accommodation. (ref) Systemic conditions can also have an influence on myopia and its progression. (ref)These include: Marfans syndrome, fetal alcohol syndrome, Crouzoan syndrome, and cerebral palsy. Another influence that has been shown to be associated with myopia and its progression is birth weight and... middle of paper... y A. (1998). The role of neural and optical factors in limiting visual resolution in myopia. Vision Research, 38(11), 1713-1721.30. Stuart JA, Burian H M. (1962). A study on the difficulty of separation. Its relation to visual acuity in normal and amblyopic eyes. American Journal Ophthalmology 53,471-477.31. Simmers AJ, Ledgeway T, Hess RF. (2004) The influences of visibility and abnormal integration processes on the perception of global spatial shape versus motion in human amblyopia. Vision Research 45, 449-460.32. Simmers AJ, Ledgeway, T Hess R F, & McGraw P V. (2003). Deficits in global motion processing in human amblyopia. Vision Research 43, 729-738.33. American Optometric Association. 2006. Optometric clinical practice guidelines for the care of the patient with myopia. [ONLINE] Available at: http://www.aoa.org/documents/CPG-15.pdf. [Accessed 20 January 12].