Manual of ophthalmic surgery and medicine / by Walter H. H. Jessop.

  • Jessop, Walter H.
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: Manual of ophthalmic surgery and medicine / by Walter H. H. Jessop. Source: Wellcome Collection.

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    place a low concave - 2 D. or - 3 D. glass in the sight-hole in order to relieve him of the necessity of relaxing his accommodation, and this glass may, by practice, be gi-adually weakened or dispensed with. To examine the fundus, the observer should care- fully search for a blood-vessel, and then, by tracing it, the optic disc will be found. It is essential to remember that in order to investigate the optic disc the patient should be told to direct his gaze in the direction.of the observer's right ear. For the examination of the yellow spot the patient must be told to look into the sight-hole of the ophthalmoscope, and by directing him to look upwards, downwards, inwards, and outwards, the details of the equator and periphery may be seen. It must be borne in mind that the image of the object investigated moves in the same du-ection as the ophthalmoscope mirror. If the patient have an error of refraction, a lens corresponding to such defect should be placed behind the sight-hole of the mirror; and if the observer himself be ametropic, his own refraction is to be corrected or allowed for. The refraction of a patient can be estimated by the observer fixing a retinal blood-vessel, and then noting the highest convex lens in hypermetropia and the lowest in myopia, by which he can accurately focus this vessel. The vitreous chamber can be explored by means of a lens of +10D. placed in the sight-hole of the ophthalmo- scope, but it is well in examining the deeper parts of the vitreous, to use lenses diminishing from +10D. to -\-lD. The lens may be investigated anteriorly by a -flS D. lens, and posteriorly by the same lens as that used for looking at the anterior part of the vitreous, namely -MO D. The cornea can be examined by a -I-20D. lens. In a normal emmetropic eye, the observer by the direct close examination should be able to investigate the