750 NOTES, CASES, INSTRUMENTS

In the deep crocodile shagreen there is no involvement of anterior structures beyond the faint opacity of Bowman's membrane which may itself represent an early mani­festation of anterior shagreen. In view of the absence of epithelial edema or vesiculation in the present case, which showed extensive involvement of the posterior aspect of the cornea, one may presume that the corneal endothelium is at least functionally in good order. By comparison with the histologic

REFINEMENT FOR T H E HAND OPHTHALMOSCOPE

RICHARD JOHN BROGGI, M.D. Worcester, Massachusetts

Since the advent of the ophthalmoscope, one of its major handicaps has been the in­convenience caused by annoying corneal re­flexes, particularly in study of the macula. This is especially true of the electric hand ophthalmoscope. In the presence of a small pupil this is annoying and frequently neces­sitates the use of mydriatics for adequate, or even permissible, ophthalmoscopic fundus examinations.

In earlier model ophthalmoscopes, this difficulty was overcome to some extent by the use of an adjustable condensing system so that, among other things, the projected circle of light could be focused and made small­er.1-3 Later on, the condensing system was made stationary in many models and a small or "pinhole" aperture was inserted which was, in most instances, placed over the con­densing lens.

findings in superficial crocodile shagreen one may guess that Descemet's membrane is in­volved to a considerable extent.

SUMMARY

A case of posterior crocodile shagreen, a rare dystrophy which may be the result of senile degeneration chiefly involving Desce­met's zone, was reported.

1777 Grand Concourse (53).

This last innovation is probably the most desirable but it has been my experience that the "pinholes" and other apertures supplied by manufacturers are generally rather large so that the projected circle of light is conse­quently too large for adequate fundus exam­ination through a small or reactive pupil. By having these apertures made smaller or more nearly a pinhole on the various models of ophthalmoscopes, however, the instruments become much easier to use in routine, white-light ophthalmoscopy. This is because of the smaller circle of light which is projected and this principle is diagrammatically illus­trated in Figure 1.

This smaller circle of light causes the cor­neal reflexes to be much less bothersome and often obviates the necessity for mydriasis even in the pupil constricted with a miotic. This principle is similar to, and in essence is, an application of Gullstrand's "simplified centric reflexless direct ophthalmoscopy" in which he used a very small, intense source of light with a reflecting ophthalmoscope.4_G

The Welch Allyn Company has made me,

REFERENCES

1. Vogt, A.: Atlas der Spaltlampen mikroskopie des lebender Auges. Berlin, Springer, 1930, v. 1. 2. Weizenblatt: Ztschr f. Augenh. 64:367, 1927. Quoted by Vogt. 3. Miiller, P.: Degenerescence en Mosaique (Chagrin de Crocodile Vogt) de la Membrane de Bowman

a la suite d'une keratite traumatique avec Hypopyn. Ann. Ocul., 182:122, 1949. 4. Valerio, M.: Arch. Ottal. 49:76, 1942. 5. Moro, F., and Amideo, B.: Relation between corneal degeneration of crocodile skin type (Vogt)

and band-shaped keratitis. Clinical and histologic study. Gior. ital. Ophtal., 6:444-464 (Sept.-Oct.) 1953. 6. Berliner, M. L.: Biomicroscopy of the Eye. New York, Hoeber, 1948, v. 1. 7. Thomas, C: The Cornea. Springfield, 111., Charles C Thomas, 1955. 8. Stacker, F. W.: Endothelium of cornea: Clinical implications. Tr. Am. Ophth. Soc, 51:669-786,

1953. 9. Calhoun. F. P.: Symposium on corneal diseases: Degenerations and dystrophies.

NOTES, CASES, INSTRUMENTS 751

K-fr.

a: -?

&

A. Fig. 1 (Broggi). (A) Light source. (B) Con­

densing lens. (C) Cap for condensing lens with larger and smaller apertures. (D) Prism. (F) Large circle of light from larger aperture. (G) Smaller circle of light from smaller aperture.

and will supply, a special drum for their no. 110 ophthalmoscope which affords a con­veniently smaller circle of projected light; they will also supply a 0.023-inch pinhole cap for their no. 106 ophthalmoscope, which gives the desired result with this model.

For the American Optical Company giant-scope, I have made my own modification by substituting a disc with a smaller central aperture which measures between 1.2 and 1.5 mm. As a result, it is possible to use a much brighter light source, which is sometimes desirable, without discomfort to the patient, and the use of the polaroid apparatus is usu­ally unnecessary. Any machine shop can make these discs with the smaller central aperture.

Both the May and Morton ophthalmo­scopes can be fitted with pinhole caps which are optimally about one half the size of those

that are originally supplied with the instru­ments. The Bausch and Lomb Optical Com­pany has supplied me with the smaller pin-hole caps for these instruments.

The Keeler Company has already incorpo­rated optimally small apertures to supplement the condensing system of most of its models of ophthalmoscopes.

This restriction of the amount of light or total light flux leaving the condensing system may be undesirable for the use of red-free and other filters in some instruments but a rheostatic control may allow the flux density to be brought to the desired level without overloading the bulb. Otherwise, it may be necessary to change to a larger sized aperture and this is, very likely, one reason for the larger apertures which are supplied with many instruments.

My personal experience has been that some instruments which I had been virtually un­able to use in routine ophtiialmoscopy, be­came easy to use in the majority of instances after this modification, without using mydria-sis. I have never found that the decreased area of fundus illumination is in any way bothersome. Moreover, it is my belief that there are many ophthalmoscopes in virtual disuse in a number of offices and clinics which could become useful instruments if this modification were made. While the use of mydriasis is necessary for a complete and thorough fundus examination, it is cer­tainly not practical nor necessary in all in­stances and an instrument which facilitates examination through a small pupil is a desira­ble one. Every funduscopist might properly or advantageously have an instrument with such a modification at his disposal.

36 Pleasant Street (8).

R E F E R E N C E S

1. Bell, W. O.: Recent advances in the construction of the ophthalmoscope. Arch. Ophth., 7:601 (Apr.) 1932.

2. Langdon, H. M.: The electric ophthalmoscope. Am. J. Ophth., 8:740 (Sept.) 1925. 3. Graves, B.: Small electric ophthalmoscopes. Brit. J. Ophth., 7:562, 1923. 4. Friedenwald, J.: A critical study of the modern ophthalmoscope. Contributions to its construction

and use. Tr. Am. Ophth. Soc, 26:381, 1928. 5. Shastid, T. H.: The ophthalmoscope. Am. Encyc. Ophth., 12:8939, 1918. 6. Examination of the eye. Am. Encyc. Ophth., 6:4758, 1915.