Volume 1

A treatise on diseases of the eye, nose, throat, and ear : for students and practitioner ... / edited by William Campbell Posey and Jonathan Wright.

Date:: 1903

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: A treatise on diseases of the eye, nose, throat, and ear : for students and practitioner ... / edited by William Campbell Posey and Jonathan Wright. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

119/764 (page 111)

$frequent. These are doubtless due to the frequently repeated strong^ contraction of the lids made in order to narrow the palpebral aperture and thus enhance the clearness of sight. This contraction leads to a more or less permanent venous congestion. GENERAL REMARKS ON METHODS OF EXAMINING FOR REFRACTIVE ERRORS. Varieties of Tests. Routine of Examination. We have various means for examining the eye for refractive errors. In some of the tests used, such as the tests of visual acuity, trial case tests, and astig- matic charts, we are dependent upon the patient's statements of what he sees. They are hence called subjective tests. In others, such as those made with the ophthalmometer, the ophthalmoscope, and, skiascopy, we are independent of the patient's statements. These are the objective tests. Usually both subjective and objective tests should be combined in making an examination. Sometimes the subjective tests are inap- plicable, as in children and illiterates; but whenever they can be apphed, they should, in general, constitute our court of last resort, and the evidence derived from them should outweigh that of the objective methods. In other words, the correcting-glass determined on is that which gives the patient the best vision, and not that which is appar- ently shown by the ophthalmoscope and shadow test. Practitioners differ a great deal in their estimates of the relative value of the tests and the way in which they should be applied in practice. It probably makes little difference what routine we adopt, provided it be systematically pursued and contains a sufficient number of tests to act as checks upon each other, and thus ensure certainty of result. I shall give briefly vty own routine, premising that I do not regard it as essentially superior to any other that may be adopted. After taking the history and getting at the symptoms I make an external and an internal examination of the eye, using in succession oblique illumination, direct illumination by transmitted light with the ophthalmoscope at ten inches, examination with the ophthalmoscope by the indirect method, and lastly examination with the ophthalmo- scope by the direct method. From this I gather, whether the eye is healthy or not, the probable amount of vision, the presence of opaci- ties or other defects interfering with sight, and approximately the state of the refraction. For the latter purpose I often add an offhand estimate with the shadow test. Those who use the ophthalmometer should here make an examina- tion with this instrument, and thus determine the amount of corneal astigmatism. The same thing may be roughly done with the Placido disk. I then take the patient's vision, and begin the test with the trial case, proceeding in the way hereafter described to determine rapidly$