Atlas of external diseases of the eye : including a brief treatise on the pathology and treatment / by O. Haab ; authorized translation from the German ; edited by G. E. DeSchweinitz.

  • Haab, O. (Otto), 1850-1931.
Date:
1909
Catalogue details

Licence: In copyright

Credit: Atlas of external diseases of the eye : including a brief treatise on the pathology and treatment / by O. Haab ; authorized translation from the German ; edited by G. E. DeSchweinitz. Source: Wellcome Collection.

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    area which, although smooth, is either depressed below, or elevated above the general level, or presents a plane surface. The latter condition is sometimes called a facet. The distortion may be general. Two conditions are possible. Either the entire surface is rough and irregulär, ör beset with numerous facets, as, for instance, after repeated ulcerations; or, more rarely, the general distor- tion of the image is due to incorrect curvature of the entire cornea, giving it a more or lcss conical shape, a condition termed keratoconus. The image is very small at the apex of the cone and increases in width as it approaches the corneal margin, where the lateral portions of the membrane (betvveen the center and the margin) take part in the reflection. Keratoconus is a serious dis- turbance to vision ; it is most surely recognized by observ- ing the nature of the corneal image—another reason for training the eye in the study of corneal changes. 3. Under certain circumstances opacity may be com- bined with irregularity of the surface, as, for example, more or less rough depressions from recent ulcers, or opaque elevations from imprisoned foreign bodies, or a rough prominence due to an epithelial neoplasm. Foreign bodies embeddcd in the cornea are a very common occur- rence in practice; their presence can always be discovered by the disturbance they cause in the corneal reflections. The following precaution is needful in many cases : Slight irregularities of the cornea, such as follow eczema, for in- stance, are more easily detected if the flow of tears is checked for a moment; hence, if it is very copious, the lids must be held open and the fluid allowed to run off, before the inspection is begun. After the condition of the corneal surface has beeil dc- termined in tliis manner, we proceed to test its trans- parency. This is often disturbed in morbid processes, notably in inflammations. Colorless blood-corpuscles in- vading the corneal tissue produce a general or local opacity, ranging, according to the kind and degree of in- 3