Refraction of the eye : its diagnosis and the correction of its errors : with a chapter on keratoscopy / by A. Stanford Morton.

Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: Refraction of the eye : its diagnosis and the correction of its errors : with a chapter on keratoscopy / by A. Stanford Morton. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    from the eye must have a divergence as if proceeding- from this point. Def. 6. A regularly astigmatic eye is that in which there is a difference of refraction in different meridians: the two principal meridians being always at right angles to each other. Astigmatism may exist in five different forms. a. Simple myopic = one meridian emmetropic the other myopic. b. Simple hypermetropic = one meridian emmetro- pic the other hypermetropic. c. Compound myopic = both meridians myopic, one more than the other. d. Compound hypermetropic = both meridians hy- permetropic one more than the other. e. Mixed = one meridian myopic, the other hyper- metropic. Def. 7. An Irregularly Astigmatic eye is one in which there are different degrees of refraction in different parts of the various meridians. Def. 8. A Presbyopic eye is that in which, owing to physiological changes, produced by advancing age, there is an inability to define small objects nearer to the eye than 22 cm. or about 9 English inches, (vide Presbyopia chap. xii.). It may exist with any of the above named conditions. From what has been stated in this and the preceding chapter we may get the following,