Myopia Prevalence and Progression (1989) / Chapter Skim
Currently Skimming:
1. Introduction
1. Introduction
Pages 3-7
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 3... ...
This is done in the eye by increasing the optical power of the lens, an act called accommodation. In contrast, in a myopic eye, the essentially parallel rays from distant objects are bent too much to form an image on the retina; rather they would form an image in front of the retina.
|
From page 4... ...
Even if this predictive power were available for the progression of young-adult-onset myopia, however, the armed forces are still faced with the problem of the size of the appropriate pool that is available with respect to refractive error. Clearly the prevalence of myopia in the young adult population, if it assumed major proportions, would be a severely limiting factor in the number of visually qualified applicants for special training in the academies, unless the visual criteria were changed.
|
From page 5... ...
Prevalence outcomes are probably affected by ethnic differences, socioeconomic factors, and educational levels. Therefore only those studies that compare similar ethnic groups, similar with respect to age distribution, gender, and socioeconomic backgrounds, can provide useful information concerning changes in prevalence over time.
|
From page 6... ...
In progression studies, a difference in refractive error from one period to another is the primary measure; therefore, reliability of the measure is critical and may be diluted when different examiners perform refractions at the two testing periods. Even when estimates of reliability are reported, often little or no attempt is made to incorporate them into interpretation of the data reflecting myopic shifts.
|
From page 7... ...
Indeed, myopia is itself best thought of as the final consequence of variations in a number of biological, sometimes pathological factors influencing refraction in the human eye. Myopia may result, for example, from an abnormally steep cornea, a crystalline lens with greater than average thickness and power, or axial elongation of the eyeball.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.