Aids to ophthalmic diagnosis / by Christopher S. Jeaffreson.

  • Jeaffreson, Christopher S.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Aids to ophthalmic diagnosis / by Christopher S. Jeaffreson. Source: Wellcome Collection.

    52/58 (page 42)
    binations of the two discs, are as follow : 4, 5, 5i*. 6, 6i, 7^, 7I 8,* 9, 10, iii 12, 14*, 15, 18, 20, 22^, 30, 374. These numbers form a useful sequence, leaving no large gap between them, and are quite suffi- cent for all practical purposes. One of the mechanical advantages of this ophthalmoscope is that the mirror is removable, and that the lenses, when employed by them- selves are sufficiently large as to be readily used as trial glasses. We can thus, on the spot, and with the same instrument, verify our ophthalmoscopic diagnosis. This will be found occasionally very useful, as a set of trial lenses is very inconvenient to carry about. *#* The numbers marked by an asterisk are not per- fectly correct, but are sufficiently so for practical purposes. The number 4f is really 4f + ^. The 8 is 8 — ^, the 5| is 5^ — ^, and the 14 is 14 + tV