. On the anomalies of accommodation and refraction of the eye, witha preliminary essay on physiological dioptrics. been supposed, fromthe increased pressure, which appeared necessarily to make thewhole eyeball more spherical. Finally, protrusion of the retinathrough firm chorioideal exudation, may give rise to some H, andby detachment of the retina it may produce even a high degree ofthe same, which, in that case, soon gives way to blindness.* The rule is, however, that H depends on a peculiar typicalstructure of the eye, which may be called the hypermetropic struc-ture. The hypermetropically-
. On the anomalies of accommodation and refraction of the eye, witha preliminary essay on physiological dioptrics. been supposed, fromthe increased pressure, which appeared necessarily to make thewhole eyeball more spherical. Finally, protrusion of the retinathrough firm chorioideal exudation, may give rise to some H, andby detachment of the retina it may produce even a high degree ofthe same, which, in that case, soon gives way to blindness.* The rule is, however, that H depends on a peculiar typicalstructure of the eye, which may be called the hypermetropic struc-ture. The hypermetropically-formed eye is a small eye; in all its * According to Ed. v. Jaeger ( Ueber die Einstellungeti des dioptr. Appara-tes, etc., Wien, 1861, p. 96) H is very characteristic and important as adiagnostic symptom in many affections of the central nervous system and ofthe optic nerve (bluish coloration combined or not with phenomena of irrita-tion). H is said in such cases often to intermit, not unfrequently simul-taneously with the symptoms of irritation. Increased tension would, underthese circumstances, be STRUCTURE OF THE HYPERMETROPIC EYE. 245 dimensions less than the emmetropic,, but especially in that ofthe visual axis. Immediately around the cornea, the sclerotic has a flat,slightly-curved appearance: the meridians have here a slight curva-ture ; at the equator, on the contrary, the curvature is much greaterin the direction of the meridians than in that of the equator section through the visual axis has the form of an ellipse, of whichthe visual axis is the short axis (Pig. 118); onthe contrary, a section perpendicular to the Fig. U8. visual axis, carried through the equator, isalmost a circle. The hypermetropic eye is ingeneral an imperfectly developed eye. If thedimensions of all the axes are less, theexpansion of the retina also is less, to which,moreover, a slighter optic nerve, and a lessnumber of its fibres correspond. Further, theasymmetry in the severa
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