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Chapter 1: INTRODUCTION

Shortsightedness has been known for more than 2000 years, but the first more exact descriptions of the condition appeared in the 19th century (Donders, 1866, Cohn, 1867 among others). There has been increasing interest within the last few decades due to the hope, that arrest of progression and, not least, prophylaxis would be possible. If this were so, then society would gain financially, as the money which is at present used for glasses and contact lenses, as well as on ophthalmological consultations could be reduced. Even more, it would also prevent the increased frequency of pathological changes, which are seen as the myopia progresses (Perkins, 1981, 1982, Daubs & Crick, 1981). At the same time, many people would be free from the discomfort arising from the use of optical aids. According to Nordic literature (Sveinsson, 1982, Fledelius, 1983, Purssinen, 1985, 1986) roughly one fourth of the population is myopic. The frequency does not appear to have increased to any great extent during the last decades, but in some areas of the world, as among Eskimos (van Rens, GHMB, 1988) or in the Far East, particularly in Taiwan (Lin et al., 1988), it has become almost epidemic and is considered to be a real health problem necessitating extensive research. This investigation was started in the hope that a longitudinal study of a uniform population, such as Danish school children, would bring new information on the course of myopia during school age, and that it might be possible to change this course by prescribing bifocal glasses, which reduce accommodation or timolol eye drops, which reduce intraocular pressure.