File:Atlas and epitome of operative ophthalmology (1905) (14779467821).jpg

Identifier: atlasepitomeofop00haab (find matches)
Title: Atlas and epitome of operative ophthalmology
Year: 1905 (1900s)
Authors: Haab, O. (Otto), b. 1850 De Schweinitz, G. E. (George Edmund), 1858-1938
Subjects: Ophthalmologic Surgical Procedures
Publisher: Philadelphia, New York (etc.) : W.B. Saunders and company
Contributing Library: University of California Libraries
Digitizing Sponsor: Internet Archive

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s often greatlydiminished by the fact that the lateral portions of thecornea and of the lens, which correspond to the newpupil, are not possessed of as equally good refractingpower as the central portion. The more peripheral thelocation of the new pupil the less distinct will be theretinal image that it makes possible; although its distinct-ness may be increased by means of a cylindric lens.Hence, the optical result of the measure is, as a rule,most satisfactory when the pupil has to be only slightlydisplaced to one side, for which purpose it is enough tocut a small piece out of the iris near the pupil. It must never be forgotten that iridectomy, unless it iscovered by the upper lid, may distress the patient by ad-mitting too much light, especially in cases of cornealopacity. For, if the pupil is not adherent to the lens,and therefore possesses its normal mobility—as, for ex-ample, when iridectomy is performed solely on account ofa corneal opacity—the pupil will remain permanently
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182 OPERATIONS ON THE EYE. dilated, because a piece of the sphincter has been removed,and the normal power of contraction has therefore beenimpaired. Corneal opacities often produce marked blind-ing, because they act like a ground-glass and diffuse thelight into the eye. The annoyance is, of course, greaterin proportion to the size of the pupil and the degree oftranslucency of the opacities. In such cases it is some-times necessary to blacken the central corneal opacity bytattooing, in order to diminish the patients discomfort. It is altogether wrong to make an optical colobomabehind an opaque cornea, even when the opacity is onlyslight. The vision is not materially improved thereby,while the patient is annoyed by the troublesome blindingeffect. If optical iridectomy is to accomplish its purpose, itmust be wholly or at least partly within the region ofthe palpebral fissure. If the greater part of the corneais opaque, the location of the iridectomy will, of course,have to be determined

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