GREEN: Improvement in Concave Spectacle-Glasses. 147
AN IMPROVEMENT IN CONCAVE SPECTACLE-GLASSES OF HIGH POWER. By DR. JOHN GREEN,
ST. LOUIS, MO. CONCAVE glasses in the higher powers are clunmsy and heavy, in consequence of their great thickness in their peripheral portions; yet the periphery of the glass is practically never used. By making the principal refracting surface small, say two centimetres in diameter, and grinding it upon one side only-that turned toward the eye-of a double-convex, double-concave, plano-convex, plano-concave, or plane glass, a single grinding-tool may be made to yield lenses of any desired focus, within a range of say eight dioptrics and with intervals not exceeding i d., or even'* dd. Glasses ground in this manner are very light, and they are all, in somiie degree, periscopic; those ground upon convex lenises are
trute menisci.
The accompanying figure shows sections of three such glasses, grourid with a tool of -20. d. (about one Paris inch radius) upon a double-convex, plane, and plano-convex lens respectively. The (louble-convex lens is of the value of 8. d. (radii. of about five Paris inches); the value of its anterior surface is therefore equal to +4. d., anid the value of the lens is equal to +4. d. - 20. d. = - i6. d. In the plano-concave lens the value of the combination is, similarly, - 4. d. - 20. d. -24. d. By thus combining the single concave surface, -20. d., with the anterior surface of any double-conivex or douible-concave lens between the limits + 8. d. and -8. d., or of any plano-concave lens ,between the limits o and -4. d., we can easily command a series ranging from -24. d. to -I6. d., with a commiion interval of .5 d.,
148
GREEN: Acute Glaucomatous Invasion
or even .25 d. Similarly, a concave surface of - i6. d. (about ii Paris inch radius) will yield a series ranging from -20. d. to -12. d., with the same comrimon interval of .5 d. or .25 d. I have to exhibit two pairs of spectacles, made after my instructions by Mr. A. P. Ecker, optician, of St. Louis. The concave surface of -i6. d. is ground in the one case upon one side of a clouble-convex lens of +8. d., giving a combination equal to +4. d. - i6. d. = -12. d., and in the other case, upon a plano-concave lens of I.5 d. givinlg a combination equal to- I.5 d. -i6. d. = -17.5 d. In the second pair of spectacles the edges of the glasses are grooved, and the weight does not exceed that of a pair of ordinary spectacles of -I5 d.
AN ACUTE GLAUCOMATOUS INVASION, FOLI OWING CLOSELY UPON A SINGLE APPLICATION OF A VERY WEAK PREPARATION OF DUBOlSIA. By DR. JOHN GREEN, ST. LOUIS, MO.
CASES of acuite attacks of glaucomiia, seemingly induced by the use of atropia, are stufficiently conimon. A similar attack has recently followed, in my hands, upon a single application of duboisia. Mrs. B., widow, aged sixty-seven, lost her right eye six years ago from acuite glaucomua, wlhichl was for a time mistaken and treated for neuralgia. The eye has remained free from pain since recovery from the acute attack, and is now soft, with a dilated )upil, a shallow anterior chanmber, and an opaque lens. Juine 7, i88o.-She called on m-le with the statenment, that visionl had been failing for miiore than a year, but that she had had no pain. Examination showed Hmii. T'X; V. k8; ptupil nlot at all dilated; anterior chamber shallow; T. +? June IIth.-I ventured to dilate the pupil by means of a small bit of paper imipregnated with duboisia extract, ulsing a piece of such size as I have found ordinarily to produce a medium grade of mydriasis in froimi thirty to forty minutes. The ophthalmoscope showed a shallow depression of the outer
AN IMPROVEMENT IN CONCAVE SPECTACLE-GLASSES OF HIGH POWER. By DR. JOHN GREEN,
ST. LOUIS, MO. CONCAVE glasses in the higher powers are clunmsy and heavy, in consequence of their great thickness in their peripheral portions; yet the periphery of the glass is practically never used. By making the principal refracting surface small, say two centimetres in diameter, and grinding it upon one side only-that turned toward the eye-of a double-convex, double-concave, plano-convex, plano-concave, or plane glass, a single grinding-tool may be made to yield lenses of any desired focus, within a range of say eight dioptrics and with intervals not exceeding i d., or even'* dd. Glasses ground in this manner are very light, and they are all, in somiie degree, periscopic; those ground upon convex lenises are
trute menisci.
The accompanying figure shows sections of three such glasses, grourid with a tool of -20. d. (about one Paris inch radius) upon a double-convex, plane, and plano-convex lens respectively. The (louble-convex lens is of the value of 8. d. (radii. of about five Paris inches); the value of its anterior surface is therefore equal to +4. d., anid the value of the lens is equal to +4. d. - 20. d. = - i6. d. In the plano-concave lens the value of the combination is, similarly, - 4. d. - 20. d. -24. d. By thus combining the single concave surface, -20. d., with the anterior surface of any double-conivex or douible-concave lens between the limits + 8. d. and -8. d., or of any plano-concave lens ,between the limits o and -4. d., we can easily command a series ranging from -24. d. to -I6. d., with a commiion interval of .5 d.,
148
GREEN: Acute Glaucomatous Invasion
or even .25 d. Similarly, a concave surface of - i6. d. (about ii Paris inch radius) will yield a series ranging from -20. d. to -12. d., with the same comrimon interval of .5 d. or .25 d. I have to exhibit two pairs of spectacles, made after my instructions by Mr. A. P. Ecker, optician, of St. Louis. The concave surface of -i6. d. is ground in the one case upon one side of a clouble-convex lens of +8. d., giving a combination equal to +4. d. - i6. d. = -12. d., and in the other case, upon a plano-concave lens of I.5 d. givinlg a combination equal to- I.5 d. -i6. d. = -17.5 d. In the second pair of spectacles the edges of the glasses are grooved, and the weight does not exceed that of a pair of ordinary spectacles of -I5 d.
AN ACUTE GLAUCOMATOUS INVASION, FOLI OWING CLOSELY UPON A SINGLE APPLICATION OF A VERY WEAK PREPARATION OF DUBOlSIA. By DR. JOHN GREEN, ST. LOUIS, MO.
CASES of acuite attacks of glaucomiia, seemingly induced by the use of atropia, are stufficiently conimon. A similar attack has recently followed, in my hands, upon a single application of duboisia. Mrs. B., widow, aged sixty-seven, lost her right eye six years ago from acuite glaucomua, wlhichl was for a time mistaken and treated for neuralgia. The eye has remained free from pain since recovery from the acute attack, and is now soft, with a dilated )upil, a shallow anterior chanmber, and an opaque lens. Juine 7, i88o.-She called on m-le with the statenment, that visionl had been failing for miiore than a year, but that she had had no pain. Examination showed Hmii. T'X; V. k8; ptupil nlot at all dilated; anterior chamber shallow; T. +? June IIth.-I ventured to dilate the pupil by means of a small bit of paper imipregnated with duboisia extract, ulsing a piece of such size as I have found ordinarily to produce a medium grade of mydriasis in froimi thirty to forty minutes. The ophthalmoscope showed a shallow depression of the outer
