. On the anomalies of accommodation and refraction of the eye, witha preliminary essay on physiological dioptrics. which the defined atrophy, per-ceptible with the ophthalmoscope, has already visibly connecteditself with a diffuse atrophy. It has, however, seemed to me, thatdiffuse atrophy occurs also where, on account of the tolerably perfectpigment-epithelium, it appears during life only from the great mu-tual distance of the still blood-carrying larger vessels of the chorioidea. In staphyloma posticum the place where the optic nerve enters theeye is important. Some years ago I investigated
. On the anomalies of accommodation and refraction of the eye, witha preliminary essay on physiological dioptrics. which the defined atrophy, per-ceptible with the ophthalmoscope, has already visibly connecteditself with a diffuse atrophy. It has, however, seemed to me, thatdiffuse atrophy occurs also where, on account of the tolerably perfectpigment-epithelium, it appears during life only from the great mu-tual distance of the still blood-carrying larger vessels of the chorioidea. In staphyloma posticum the place where the optic nerve enters theeye is important. Some years ago I investigated this place in thenormal It then appeared to me, that the trunk of the optic* Archiv fur Ophthal, Bd. i. h. 2, pp. 82 et seq. 1855. ENTRANCE OF THE OPTIC NERVE. 375 nerve is already divided by fibrous tissue into the numerous smallbundles into which it at once separates on issuing as retina, andthus differs essentially in its structure from other gradually ramifyingnerve-trunks; that it possesses a double fibrous sheath, an externaland thicker one, a (Fig. 145), which is continued at a into the 1%. most external part of the sclerotic, and an internal one b, which en-velopes the trunk as far as the chorioidea d, is connected with thelatter, and bends close to it into the there pigment-containing scleroticb} while at the same time the lamina cribrosa g for the most partproceeds therefrom, and is only to a small extent formed by the cho-rioidea. Between the two fibrous sheaths, a and b, is a thin layerof loose connective tissue, the connective-tissue-sheath c, consistingof a network of sharply-defined fasciculi, which ascends to c cioseto the lamina cribrosa. Even beneath the lamina cribrosa at h thenerve-fibres, as Bowman* first stated, lose their medullary sheath,whereby the nerve becomes thinner and at the same time transparent. * Lectures on the parts concerned in the operations on the , p. 82. London. 376 MYOPIA. These thinner fasciculi now pass through the
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