Atlas and epitome of ophthalmoscopy and ophthalmoscopic diagnosis / by O. Haab.

  • Haab, O. (Otto), 1850-1931.
Date:
1910
Catalogue details

Licence: In copyright

Credit: Atlas and epitome of ophthalmoscopy and ophthalmoscopic diagnosis / by O. Haab. Source: Wellcome Collection.

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    borne in mind that the correcting lenses found with the ophthalraoscope will be too strong in myopia and too weak in hypermetropia, if the observer’s eye is too far away from the eye examined. In such a case, therefore, the myopia of the eye examined is weaker and the hypermetropia stronger than the lens in the ophthal- moscope. Säze of the Ophthalmoscopic Field of Vision. Another reason for coming as close as possible to the eye linder examination is that it is easier in that way to look into the eye through the comparatively narrow pupil. By coming as close to the pupil as possible the observer is able to see a larger portion of the eye-ground without changing the relative positions of his own and the patient’s eye ; in other words, the ophthalmoscopic field of vision is increased. If the pupil is very small, it must be dilated either by shielding the other eye from the light, or by means of drugs—homatropin in 2 per cent., or euphthal- min in 5 per cent. Solutions. From 2 to 3 drops instilled within five minutes usually suffice to produce the desired amount of dilatation within twenty minutes. The use of atropin for tliis purpose is to be avoided as much as possible, as its action lasts too long and may produce increased intraoeular tension (glaucoma), especially in elderly people. [No mydriatic is entirely free from the danger of producing glaucoma; even euphthalmin has caused tliis disease, witness a case reported bv Knapp. Euphthalmin mydriasis may be ncutralized by the instilla- tion of a pilocarpin solution (gr. j-filj) before the patient is dismissed.—Ed.] An experienced observer will very rarely need to dilate the pupil artificially in a normal eye unless he particularly Avishes to examine the macular region. For tliis purpose artificial dilatation is often indispensable, especially in elderly people, who usually have smaller pupils than young persons. For similar reasons the opening in