The crystalline lens system : its embryology, anatomy, physiological chemistry, physiology, pathology, diseases, treatment, operations and after-changes ; with a consideration of aphakia / by Louis Stricker.

  • Stricker, Louis, 1863-
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: The crystalline lens system : its embryology, anatomy, physiological chemistry, physiology, pathology, diseases, treatment, operations and after-changes ; with a consideration of aphakia / by Louis Stricker. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    The Second or Extrauterine period of growth is essentially a continua- tion of ilic firsi period, with this difference, namely, a diametrically oppo- site process begins, which we will designate as one of PHYSIOLOGICAL RETROGRESSION. These diametrically opposite conditions divide the extra-uterine period Into two great periods, one of extra-uterine growth, up to its complete development; the oilier, that of retrogression together with the changes incident to a reduction in volume. How great the increase in volume is, may be judged by the following: The weight of a lens taken from a foetus in which the total ocular axis measured L5 mm., was 0.07 grammes, (Becker), whereas, at birth, in an eye having an ocular axis of 17mm.the lens weighed 0.10 grammes, (Becker),and Sappey estimates the average weight of an adult lens at 0.218 grm. This increase in volume is accompanied by a very natural increase in the equatorial diameter of from 5 mm. to 10 mm., whereas the saggital diam- eter, the axis of the lens according to Sappey, remains almost unchanged, -1 to 4.5 mm. The lens of the human foetus and of the new-born child is almost globular, whereas in an adult the surface has a much sharper curva- ture. In the following table the absolute weight agrees exactly with the state- ments of Sappey. Weight and volume (with but one exception) increase steadily with age. The specific gravity varies slightly from the average. The extremes, however, bear no close relationship to the age. Some slight doubt is cast on the accuracy of these results, because the lenses had been in Midler's fluid for various periods, some for several years; and further, because the number of examinations is not large enough. All the lenses were obtained post mortem. No. AGE. Absolute Volume. Specific Weight. Cu. Ctm. Gravity. Gr. 1 Foetus. 0.070 2 At Birth. 0.10 3 20 yrs. 0.18 0.155 1.16129 4 20 0.185 0.159 1.16352 5 22 0.215 0.177 1.13158 (5 40 • 0.190 0.153 1.24248 7 49 0.225 0.194 1.15979 8 49 0.240 0.198 1.21212 9 54 0.245 0.214 1.14486 10 54 0.245 0.214 1.14486 11 60 0.261 0.217 1.15668 Average . . . 0.219 0.198 1.16946 Priesthey Smith i has verified all Becker's statements, at the same lOph. Society. 1883, p. 70, reprinted in his monograph. The Pathology and Treatment of Glaucoma, 1801.