Genetics in ophthalmology / Arnold Sorsby.

  • Sorsby, Arnold, 1900-1980.
Date:
1951
Catalogue details

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

Credit: Genetics in ophthalmology / Arnold Sorsby. Source: Wellcome Collection.

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    THE GLOBE AS A WHOLE refractions at the extreme of the myopia component of the curve (Fig. 63). The second of these deviations emphasizes that high myopia falls outside the range of normal refractions—as already seen from the study of axial lengths. The excess of refractions towards emmetropia must be taken to show that the individual components of total refraction are not freely variable, as held by Steiger, but correlated towards the production of an excess of emmetropes. The nature of this correlating mechanism towards emmetropization is unknown. Any study of ametropia must, therefore, take into account these two significant departures from the original hypothesis: 0) High myopia is not a physiological variant. (2) There is no free variation of the individual components of refraction. On the contrary, these are correlated by some mechanism. Fig. 64.—Distribution of the refractive errors under atropine cycloplegia in a composite series of 2,398 newborn infants. Negative values = hypermetropia; positive values = myopia in diopters. Continuous curve = actual distribution; broken curve = theore¬ tical binomial curve (Wibaut). {After F. Wibaut (1925) Arch.f. Ophthal. 116, 596.) 8-7-6-5-4-3-2-l-E+l + 2^1 Fig. 65. (After A. Sorsby (1938). Trans. Ophthal. Soc. U.K., 57, 394.) 84